You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
postgres/src/backend/utils/init/postinit.c

1269 lines
37 KiB

/*-------------------------------------------------------------------------
*
* postinit.c
* postgres initialization utilities
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/utils/init/postinit.c
*
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <ctype.h>
#include <fcntl.h>
#include <unistd.h>
#include "access/genam.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/session.h"
#include "access/sysattr.h"
tableam: Add and use scan APIs. Too allow table accesses to be not directly dependent on heap, several new abstractions are needed. Specifically: 1) Heap scans need to be generalized into table scans. Do this by introducing TableScanDesc, which will be the "base class" for individual AMs. This contains the AM independent fields from HeapScanDesc. The previous heap_{beginscan,rescan,endscan} et al. have been replaced with a table_ version. There's no direct replacement for heap_getnext(), as that returned a HeapTuple, which is undesirable for a other AMs. Instead there's table_scan_getnextslot(). But note that heap_getnext() lives on, it's still used widely to access catalog tables. This is achieved by new scan_begin, scan_end, scan_rescan, scan_getnextslot callbacks. 2) The portion of parallel scans that's shared between backends need to be able to do so without the user doing per-AM work. To achieve that new parallelscan_{estimate, initialize, reinitialize} callbacks are introduced, which operate on a new ParallelTableScanDesc, which again can be subclassed by AMs. As it is likely that several AMs are going to be block oriented, block oriented callbacks that can be shared between such AMs are provided and used by heap. table_block_parallelscan_{estimate, intiialize, reinitialize} as callbacks, and table_block_parallelscan_{nextpage, init} for use in AMs. These operate on a ParallelBlockTableScanDesc. 3) Index scans need to be able to access tables to return a tuple, and there needs to be state across individual accesses to the heap to store state like buffers. That's now handled by introducing a sort-of-scan IndexFetchTable, which again is intended to be subclassed by individual AMs (for heap IndexFetchHeap). The relevant callbacks for an AM are index_fetch_{end, begin, reset} to create the necessary state, and index_fetch_tuple to retrieve an indexed tuple. Note that index_fetch_tuple implementations need to be smarter than just blindly fetching the tuples for AMs that have optimizations similar to heap's HOT - the currently alive tuple in the update chain needs to be fetched if appropriate. Similar to table_scan_getnextslot(), it's undesirable to continue to return HeapTuples. Thus index_fetch_heap (might want to rename that later) now accepts a slot as an argument. Core code doesn't have a lot of call sites performing index scans without going through the systable_* API (in contrast to loads of heap_getnext calls and working directly with HeapTuples). Index scans now store the result of a search in IndexScanDesc->xs_heaptid, rather than xs_ctup->t_self. As the target is not generally a HeapTuple anymore that seems cleaner. To be able to sensible adapt code to use the above, two further callbacks have been introduced: a) slot_callbacks returns a TupleTableSlotOps* suitable for creating slots capable of holding a tuple of the AMs type. table_slot_callbacks() and table_slot_create() are based upon that, but have additional logic to deal with views, foreign tables, etc. While this change could have been done separately, nearly all the call sites that needed to be adapted for the rest of this commit also would have been needed to be adapted for table_slot_callbacks(), making separation not worthwhile. b) tuple_satisfies_snapshot checks whether the tuple in a slot is currently visible according to a snapshot. That's required as a few places now don't have a buffer + HeapTuple around, but a slot (which in heap's case internally has that information). Additionally a few infrastructure changes were needed: I) SysScanDesc, as used by systable_{beginscan, getnext} et al. now internally uses a slot to keep track of tuples. While systable_getnext() still returns HeapTuples, and will so for the foreseeable future, the index API (see 1) above) now only deals with slots. The remainder, and largest part, of this commit is then adjusting all scans in postgres to use the new APIs. Author: Andres Freund, Haribabu Kommi, Alvaro Herrera Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de https://postgr.es/m/20160812231527.GA690404@alvherre.pgsql
6 years ago
#include "access/tableam.h"
#include "access/xact.h"
#include "access/xlog.h"
#include "access/xloginsert.h"
#include "catalog/catalog.h"
#include "catalog/namespace.h"
#include "catalog/pg_authid.h"
#include "catalog/pg_database.h"
#include "catalog/pg_db_role_setting.h"
#include "catalog/pg_tablespace.h"
#include "libpq/auth.h"
#include "libpq/libpq-be.h"
#include "mb/pg_wchar.h"
26 years ago
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/autovacuum.h"
#include "postmaster/postmaster.h"
#include "replication/walsender.h"
#include "storage/bufmgr.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/lmgr.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "storage/procsignal.h"
#include "storage/sinvaladt.h"
26 years ago
#include "storage/smgr.h"
#include "storage/sync.h"
#include "tcop/tcopprot.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/pg_locale.h"
26 years ago
#include "utils/portal.h"
#include "utils/ps_status.h"
#include "utils/snapmgr.h"
26 years ago
#include "utils/syscache.h"
#include "utils/timeout.h"
static HeapTuple GetDatabaseTuple(const char *dbname);
static HeapTuple GetDatabaseTupleByOid(Oid dboid);
static void PerformAuthentication(Port *port);
static void CheckMyDatabase(const char *name, bool am_superuser, bool override_allow_connections);
static void ShutdownPostgres(int code, Datum arg);
static void StatementTimeoutHandler(void);
static void LockTimeoutHandler(void);
static void IdleInTransactionSessionTimeoutHandler(void);
static void IdleSessionTimeoutHandler(void);
static void ClientCheckTimeoutHandler(void);
static bool ThereIsAtLeastOneRole(void);
static void process_startup_options(Port *port, bool am_superuser);
static void process_settings(Oid databaseid, Oid roleid);
/*** InitPostgres support ***/
/*
* GetDatabaseTuple -- fetch the pg_database row for a database
*
* This is used during backend startup when we don't yet have any access to
* system catalogs in general. In the worst case, we can seqscan pg_database
* using nothing but the hard-wired descriptor that relcache.c creates for
* pg_database. In more typical cases, relcache.c was able to load
* descriptors for both pg_database and its indexes from the shared relcache
* cache file, and so we can do an indexscan. criticalSharedRelcachesBuilt
* tells whether we got the cached descriptors.
*/
static HeapTuple
GetDatabaseTuple(const char *dbname)
{
HeapTuple tuple;
Relation relation;
SysScanDesc scan;
ScanKeyData key[1];
/*
* form a scan key
*/
ScanKeyInit(&key[0],
Anum_pg_database_datname,
BTEqualStrategyNumber, F_NAMEEQ,
CStringGetDatum(dbname));
/*
* Open pg_database and fetch a tuple. Force heap scan if we haven't yet
* built the critical shared relcache entries (i.e., we're starting up
* without a shared relcache cache file).
*/
relation = table_open(DatabaseRelationId, AccessShareLock);
scan = systable_beginscan(relation, DatabaseNameIndexId,
criticalSharedRelcachesBuilt,
NULL,
1, key);
tuple = systable_getnext(scan);
/* Must copy tuple before releasing buffer */
if (HeapTupleIsValid(tuple))
tuple = heap_copytuple(tuple);
/* all done */
systable_endscan(scan);
table_close(relation, AccessShareLock);
return tuple;
}
/*
* GetDatabaseTupleByOid -- as above, but search by database OID
*/
static HeapTuple
GetDatabaseTupleByOid(Oid dboid)
{
HeapTuple tuple;
Relation relation;
SysScanDesc scan;
ScanKeyData key[1];
/*
* form a scan key
*/
ScanKeyInit(&key[0],
Remove WITH OIDS support, change oid catalog column visibility. Previously tables declared WITH OIDS, including a significant fraction of the catalog tables, stored the oid column not as a normal column, but as part of the tuple header. This special column was not shown by default, which was somewhat odd, as it's often (consider e.g. pg_class.oid) one of the more important parts of a row. Neither pg_dump nor COPY included the contents of the oid column by default. The fact that the oid column was not an ordinary column necessitated a significant amount of special case code to support oid columns. That already was painful for the existing, but upcoming work aiming to make table storage pluggable, would have required expanding and duplicating that "specialness" significantly. WITH OIDS has been deprecated since 2005 (commit ff02d0a05280e0). Remove it. Removing includes: - CREATE TABLE and ALTER TABLE syntax for declaring the table to be WITH OIDS has been removed (WITH (oids[ = true]) will error out) - pg_dump does not support dumping tables declared WITH OIDS and will issue a warning when dumping one (and ignore the oid column). - restoring an pg_dump archive with pg_restore will warn when restoring a table with oid contents (and ignore the oid column) - COPY will refuse to load binary dump that includes oids. - pg_upgrade will error out when encountering tables declared WITH OIDS, they have to be altered to remove the oid column first. - Functionality to access the oid of the last inserted row (like plpgsql's RESULT_OID, spi's SPI_lastoid, ...) has been removed. The syntax for declaring a table WITHOUT OIDS (or WITH (oids = false) for CREATE TABLE) is still supported. While that requires a bit of support code, it seems unnecessary to break applications / dumps that do not use oids, and are explicit about not using them. The biggest user of WITH OID columns was postgres' catalog. This commit changes all 'magic' oid columns to be columns that are normally declared and stored. To reduce unnecessary query breakage all the newly added columns are still named 'oid', even if a table's column naming scheme would indicate 'reloid' or such. This obviously requires adapting a lot code, mostly replacing oid access via HeapTupleGetOid() with access to the underlying Form_pg_*->oid column. The bootstrap process now assigns oids for all oid columns in genbki.pl that do not have an explicit value (starting at the largest oid previously used), only oids assigned later by oids will be above FirstBootstrapObjectId. As the oid column now is a normal column the special bootstrap syntax for oids has been removed. Oids are not automatically assigned during insertion anymore, all backend code explicitly assigns oids with GetNewOidWithIndex(). For the rare case that insertions into the catalog via SQL are called for the new pg_nextoid() function can be used (which only works on catalog tables). The fact that oid columns on system tables are now normal columns means that they will be included in the set of columns expanded by * (i.e. SELECT * FROM pg_class will now include the table's oid, previously it did not). It'd not technically be hard to hide oid column by default, but that'd mean confusing behavior would either have to be carried forward forever, or it'd cause breakage down the line. While it's not unlikely that further adjustments are needed, the scope/invasiveness of the patch makes it worthwhile to get merge this now. It's painful to maintain externally, too complicated to commit after the code code freeze, and a dependency of a number of other patches. Catversion bump, for obvious reasons. Author: Andres Freund, with contributions by John Naylor Discussion: https://postgr.es/m/20180930034810.ywp2c7awz7opzcfr@alap3.anarazel.de
7 years ago
Anum_pg_database_oid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(dboid));
/*
* Open pg_database and fetch a tuple. Force heap scan if we haven't yet
* built the critical shared relcache entries (i.e., we're starting up
* without a shared relcache cache file).
*/
relation = table_open(DatabaseRelationId, AccessShareLock);
scan = systable_beginscan(relation, DatabaseOidIndexId,
criticalSharedRelcachesBuilt,
NULL,
1, key);
tuple = systable_getnext(scan);
/* Must copy tuple before releasing buffer */
if (HeapTupleIsValid(tuple))
tuple = heap_copytuple(tuple);
/* all done */
systable_endscan(scan);
table_close(relation, AccessShareLock);
return tuple;
}
/*
* PerformAuthentication -- authenticate a remote client
*
* returns: nothing. Will not return at all if there's any failure.
*/
static void
PerformAuthentication(Port *port)
{
/* This should be set already, but let's make sure */
ClientAuthInProgress = true; /* limit visibility of log messages */
/*
* In EXEC_BACKEND case, we didn't inherit the contents of pg_hba.conf
* etcetera from the postmaster, and have to load them ourselves.
*
* FIXME: [fork/exec] Ugh. Is there a way around this overhead?
*/
#ifdef EXEC_BACKEND
/*
* load_hba() and load_ident() want to work within the PostmasterContext,
* so create that if it doesn't exist (which it won't). We'll delete it
* again later, in PostgresMain.
*/
if (PostmasterContext == NULL)
PostmasterContext = AllocSetContextCreate(TopMemoryContext,
"Postmaster",
Add macros to make AllocSetContextCreate() calls simpler and safer. I found that half a dozen (nearly 5%) of our AllocSetContextCreate calls had typos in the context-sizing parameters. While none of these led to especially significant problems, they did create minor inefficiencies, and it's now clear that expecting people to copy-and-paste those calls accurately is not a great idea. Let's reduce the risk of future errors by introducing single macros that encapsulate the common use-cases. Three such macros are enough to cover all but two special-purpose contexts; those two calls can be left as-is, I think. While this patch doesn't in itself improve matters for third-party extensions, it doesn't break anything for them either, and they can gradually adopt the simplified notation over time. In passing, change TopMemoryContext to use the default allocation parameters. Formerly it could only be extended 8K at a time. That was probably reasonable when this code was written; but nowadays we create many more contexts than we did then, so that it's not unusual to have a couple hundred K in TopMemoryContext, even without considering various dubious code that sticks other things there. There seems no good reason not to let it use growing blocks like most other contexts. Back-patch to 9.6, mostly because that's still close enough to HEAD that it's easy to do so, and keeping the branches in sync can be expected to avoid some future back-patching pain. The bugs fixed by these changes don't seem to be significant enough to justify fixing them further back. Discussion: <21072.1472321324@sss.pgh.pa.us>
9 years ago
ALLOCSET_DEFAULT_SIZES);
if (!load_hba())
{
/*
* It makes no sense to continue if we fail to load the HBA file,
* since there is no way to connect to the database in this case.
*/
ereport(FATAL,
(errmsg("could not load pg_hba.conf")));
}
if (!load_ident())
{
/*
* It is ok to continue if we fail to load the IDENT file, although it
* means that you cannot log in using any of the authentication
* methods that need a user name mapping. load_ident() already logged
* the details of error to the log.
*/
}
#endif
/*
* Set up a timeout in case a buggy or malicious client fails to respond
* during authentication. Since we're inside a transaction and might do
* database access, we have to use the statement_timeout infrastructure.
*/
enable_timeout_after(STATEMENT_TIMEOUT, AuthenticationTimeout * 1000);
/*
* Now perform authentication exchange.
*/
set_ps_display("authentication");
ClientAuthentication(port); /* might not return, if failure */
/*
* Done with authentication. Disable the timeout, and log if needed.
*/
disable_timeout(STATEMENT_TIMEOUT, false);
if (Log_connections)
{
StringInfoData logmsg;
initStringInfo(&logmsg);
if (am_walsender)
appendStringInfo(&logmsg, _("replication connection authorized: user=%s"),
port->user_name);
else
appendStringInfo(&logmsg, _("connection authorized: user=%s"),
port->user_name);
if (!am_walsender)
appendStringInfo(&logmsg, _(" database=%s"), port->database_name);
if (port->application_name != NULL)
appendStringInfo(&logmsg, _(" application_name=%s"),
port->application_name);
#ifdef USE_SSL
if (port->ssl_in_use)
appendStringInfo(&logmsg, _(" SSL enabled (protocol=%s, cipher=%s, bits=%d)"),
be_tls_get_version(port),
be_tls_get_cipher(port),
be_tls_get_cipher_bits(port));
#endif
#ifdef ENABLE_GSS
Fix assorted issues in backend's GSSAPI encryption support. Unrecoverable errors detected by GSSAPI encryption can't just be reported with elog(ERROR) or elog(FATAL), because attempting to send the error report to the client is likely to lead to infinite recursion or loss of protocol sync. Instead make this code do what the SSL encryption code has long done, which is to just report any such failure to the server log (with elevel COMMERROR), then pretend we've lost the connection by returning errno = ECONNRESET. Along the way, fix confusion about whether message translation is done by pg_GSS_error() or its callers (the latter should do it), and make the backend version of that function work more like the frontend version. Avoid allocating the port->gss struct until it's needed; we surely don't need to allocate it in the postmaster. Improve logging of "connection authorized" messages with GSS enabled. (As part of this, I back-patched the code changes from dc11f31a1.) Make BackendStatusShmemSize() account for the GSS-related space that will be allocated by CreateSharedBackendStatus(). This omission could possibly cause out-of-shared-memory problems with very high max_connections settings. Remove arbitrary, pointless restriction that only GSS authentication can be used on a GSS-encrypted connection. Improve documentation; notably, document the fact that libpq now prefers GSS encryption over SSL encryption if both are possible. Per report from Mikael Gustavsson. Back-patch to v12 where this code was introduced. Discussion: https://postgr.es/m/e5b0b6ed05764324a2f3fe7acfc766d5@smhi.se
5 years ago
if (port->gss)
{
const char *princ = be_gssapi_get_princ(port);
if (princ)
appendStringInfo(&logmsg,
_(" GSS (authenticated=%s, encrypted=%s, principal=%s)"),
be_gssapi_get_auth(port) ? _("yes") : _("no"),
be_gssapi_get_enc(port) ? _("yes") : _("no"),
princ);
else
appendStringInfo(&logmsg,
_(" GSS (authenticated=%s, encrypted=%s)"),
be_gssapi_get_auth(port) ? _("yes") : _("no"),
be_gssapi_get_enc(port) ? _("yes") : _("no"));
}
#endif
ereport(LOG, errmsg_internal("%s", logmsg.data));
pfree(logmsg.data);
}
set_ps_display("startup");
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
8 years ago
ClientAuthInProgress = false; /* client_min_messages is active now */
}
/*
* CheckMyDatabase -- fetch information from the pg_database entry for our DB
*/
static void
CheckMyDatabase(const char *name, bool am_superuser, bool override_allow_connections)
{
HeapTuple tup;
Form_pg_database dbform;
Datum datum;
bool isnull;
char *collate;
char *ctype;
/* Fetch our pg_database row normally, via syscache */
tup = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
if (!HeapTupleIsValid(tup))
elog(ERROR, "cache lookup failed for database %u", MyDatabaseId);
dbform = (Form_pg_database) GETSTRUCT(tup);
/* This recheck is strictly paranoia */
if (strcmp(name, NameStr(dbform->datname)) != 0)
ereport(FATAL,
(errcode(ERRCODE_UNDEFINED_DATABASE),
errmsg("database \"%s\" has disappeared from pg_database",
name),
errdetail("Database OID %u now seems to belong to \"%s\".",
MyDatabaseId, NameStr(dbform->datname))));
/*
* Check permissions to connect to the database.
*
* These checks are not enforced when in standalone mode, so that there is
* a way to recover from disabling all access to all databases, for
* example "UPDATE pg_database SET datallowconn = false;".
*
* We do not enforce them for autovacuum worker processes either.
*/
if (IsUnderPostmaster && !IsAutoVacuumWorkerProcess())
{
/*
* Check that the database is currently allowing connections.
*/
if (!dbform->datallowconn && !override_allow_connections)
ereport(FATAL,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("database \"%s\" is not currently accepting connections",
name)));
/*
* Check privilege to connect to the database. (The am_superuser test
* is redundant, but since we have the flag, might as well check it
* and save a few cycles.)
*/
if (!am_superuser &&
pg_database_aclcheck(MyDatabaseId, GetUserId(),
ACL_CONNECT) != ACLCHECK_OK)
ereport(FATAL,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied for database \"%s\"", name),
errdetail("User does not have CONNECT privilege.")));
/*
* Check connection limit for this database.
*
* There is a race condition here --- we create our PGPROC before
* checking for other PGPROCs. If two backends did this at about the
* same time, they might both think they were over the limit, while
* ideally one should succeed and one fail. Getting that to work
* exactly seems more trouble than it is worth, however; instead we
* just document that the connection limit is approximate.
*/
if (dbform->datconnlimit >= 0 &&
!am_superuser &&
CountDBConnections(MyDatabaseId) > dbform->datconnlimit)
ereport(FATAL,
(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
errmsg("too many connections for database \"%s\"",
name)));
}
/*
* OK, we're golden. Next to-do item is to save the encoding info out of
* the pg_database tuple.
*/
SetDatabaseEncoding(dbform->encoding);
/* Record it as a GUC internal option, too */
SetConfigOption("server_encoding", GetDatabaseEncodingName(),
PGC_INTERNAL, PGC_S_OVERRIDE);
/* If we have no other source of client_encoding, use server encoding */
SetConfigOption("client_encoding", GetDatabaseEncodingName(),
Split PGC_S_DEFAULT into two values, for true boot_val vs computed default. Failure to distinguish these cases is the real cause behind the recent reports of Windows builds crashing on 'infinity'::timestamp, which was directly due to failure to establish a value of timezone_abbreviations in postmaster child processes. The postmaster had the desired value, but write_one_nondefault_variable() didn't transmit it to backends. To fix that, invent a new value PGC_S_DYNAMIC_DEFAULT, and be sure to use that or PGC_S_ENV_VAR (as appropriate) for "default" settings that are computed during initialization. (We need both because there's at least one variable that could receive a value from either source.) This commit also fixes ProcessConfigFile's failure to restore the correct default value for certain GUC variables if they are set in postgresql.conf and then removed/commented out of the file. We have to recompute and reinstall the value for any GUC variable that could have received a value from PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR sources, and there were a number of oversights. (That whole thing is a crock that needs to be redesigned, but not today.) However, I intentionally didn't make it work "exactly right" for the cases of timezone and log_timezone. The exactly right behavior would involve running select_default_timezone, which we'd have to do independently in each postgres process, causing the whole database to become entirely unresponsive for as much as several seconds. That didn't seem like a good idea, especially since the variable's removal from postgresql.conf might be just an accidental edit. Instead the behavior is to adopt the previously active setting as if it were default. Note that this patch creates an ABI break for extensions that use any of the PGC_S_XXX constants; they'll need to be recompiled.
14 years ago
PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
/* assign locale variables */
datum = SysCacheGetAttr(DATABASEOID, tup, Anum_pg_database_datcollate, &isnull);
Assert(!isnull);
collate = TextDatumGetCString(datum);
datum = SysCacheGetAttr(DATABASEOID, tup, Anum_pg_database_datctype, &isnull);
Assert(!isnull);
ctype = TextDatumGetCString(datum);
if (pg_perm_setlocale(LC_COLLATE, collate) == NULL)
ereport(FATAL,
(errmsg("database locale is incompatible with operating system"),
errdetail("The database was initialized with LC_COLLATE \"%s\", "
" which is not recognized by setlocale().", collate),
errhint("Recreate the database with another locale or install the missing locale.")));
if (pg_perm_setlocale(LC_CTYPE, ctype) == NULL)
ereport(FATAL,
(errmsg("database locale is incompatible with operating system"),
errdetail("The database was initialized with LC_CTYPE \"%s\", "
" which is not recognized by setlocale().", ctype),
errhint("Recreate the database with another locale or install the missing locale.")));
/* Make the locale settings visible as GUC variables, too */
SetConfigOption("lc_collate", collate, PGC_INTERNAL, PGC_S_OVERRIDE);
SetConfigOption("lc_ctype", ctype, PGC_INTERNAL, PGC_S_OVERRIDE);
23 years ago
check_strxfrm_bug();
ReleaseSysCache(tup);
}
/*
* pg_split_opts -- split a string of options and append it to an argv array
*
* The caller is responsible for ensuring the argv array is large enough. The
* maximum possible number of arguments added by this routine is
* (strlen(optstr) + 1) / 2.
*
* Because some option values can contain spaces we allow escaping using
* backslashes, with \\ representing a literal backslash.
*/
void
pg_split_opts(char **argv, int *argcp, const char *optstr)
{
StringInfoData s;
initStringInfo(&s);
while (*optstr)
{
bool last_was_escape = false;
resetStringInfo(&s);
/* skip over leading space */
while (isspace((unsigned char) *optstr))
optstr++;
if (*optstr == '\0')
break;
/*
* Parse a single option, stopping at the first space, unless it's
* escaped.
*/
while (*optstr)
{
if (isspace((unsigned char) *optstr) && !last_was_escape)
break;
if (!last_was_escape && *optstr == '\\')
last_was_escape = true;
else
{
last_was_escape = false;
appendStringInfoChar(&s, *optstr);
}
optstr++;
}
/* now store the option in the next argv[] position */
argv[(*argcp)++] = pstrdup(s.data);
}
pfree(s.data);
}
/*
* Initialize MaxBackends value from config options.
*
* This must be called after modules have had the chance to alter GUCs in
* shared_preload_libraries and before shared memory size is determined.
*
* Note that in EXEC_BACKEND environment, the value is passed down from
* postmaster to subprocesses via BackendParameters in SubPostmasterMain; only
* postmaster itself and processes not under postmaster control should call
* this.
*/
void
InitializeMaxBackends(void)
{
Assert(MaxBackends == 0);
/* the extra unit accounts for the autovacuum launcher */
MaxBackends = MaxConnections + autovacuum_max_workers + 1 +
max_worker_processes + max_wal_senders;
/* internal error because the values were all checked previously */
if (MaxBackends > MAX_BACKENDS)
elog(ERROR, "too many backends configured");
}
/*
* Early initialization of a backend (either standalone or under postmaster).
* This happens even before InitPostgres.
*
* This is separate from InitPostgres because it is also called by auxiliary
* processes, such as the background writer process, which may not call
* InitPostgres at all.
*/
void
BaseInit(void)
{
Assert(MyProc != NULL);
/*
* Initialize our input/output/debugging file descriptors.
*/
DebugFileOpen();
Move temporary file cleanup to before_shmem_exit(). As reported by a few OSX buildfarm animals there exist at least one path where temporary files exist during AtProcExit_Files() processing. As temporary file cleanup causes pgstat reporting, the assertions added in ee3f8d3d3ae caused failures. This is not an OSX specific issue, we were just lucky that timing on OSX reliably triggered the problem. The known way to cause this is a FATAL error during perform_base_backup() with a MANIFEST used - adding an elog(FATAL) after InitializeBackupManifest() reliably reproduces the problem in isolation. The problem is that the temporary file created in InitializeBackupManifest() is not cleaned up via resource owner cleanup as WalSndResourceCleanup() currently is only used for non-FATAL errors. That then allows to reach AtProcExit_Files() with existing temporary files, causing the assertion failure. To fix this problem, move temporary file cleanup to a before_shmem_exit() hook and add assertions ensuring that no temporary files are created before / after temporary file management has been initialized / shut down. The cleanest way to do so seems to be to split fd.c initialization into two, one for plain file access and one for temporary file access. Right now there's no need to perform further fd.c cleanup during process exit, so I just renamed AtProcExit_Files() to BeforeShmemExit_Files(). Alternatively we could perform another pass through the files to check that no temporary files exist, but the added assertions seem to provide enough protection against that. It might turn out that the assertions added in ee3f8d3d3ae will cause too much noise - in that case we'll have to downgrade them to a WARNING, at least temporarily. This commit is not necessarily the best approach to address this issue, but it should resolve the buildfarm failures. We can revise later. Author: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/20210807190131.2bm24acbebl4wl6i@alap3.anarazel.de
4 years ago
/*
* Initialize file access. Done early so other subsystems can access
* files.
*/
InitFileAccess();
/*
* Initialize statistics reporting. This needs to happen early to ensure
* that pgstat's shutdown callback runs after the shutdown callbacks of
* all subsystems that can produce stats (like e.g. transaction commits
* can).
*/
pgstat_initialize();
Move temporary file cleanup to before_shmem_exit(). As reported by a few OSX buildfarm animals there exist at least one path where temporary files exist during AtProcExit_Files() processing. As temporary file cleanup causes pgstat reporting, the assertions added in ee3f8d3d3ae caused failures. This is not an OSX specific issue, we were just lucky that timing on OSX reliably triggered the problem. The known way to cause this is a FATAL error during perform_base_backup() with a MANIFEST used - adding an elog(FATAL) after InitializeBackupManifest() reliably reproduces the problem in isolation. The problem is that the temporary file created in InitializeBackupManifest() is not cleaned up via resource owner cleanup as WalSndResourceCleanup() currently is only used for non-FATAL errors. That then allows to reach AtProcExit_Files() with existing temporary files, causing the assertion failure. To fix this problem, move temporary file cleanup to a before_shmem_exit() hook and add assertions ensuring that no temporary files are created before / after temporary file management has been initialized / shut down. The cleanest way to do so seems to be to split fd.c initialization into two, one for plain file access and one for temporary file access. Right now there's no need to perform further fd.c cleanup during process exit, so I just renamed AtProcExit_Files() to BeforeShmemExit_Files(). Alternatively we could perform another pass through the files to check that no temporary files exist, but the added assertions seem to provide enough protection against that. It might turn out that the assertions added in ee3f8d3d3ae will cause too much noise - in that case we'll have to downgrade them to a WARNING, at least temporarily. This commit is not necessarily the best approach to address this issue, but it should resolve the buildfarm failures. We can revise later. Author: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/20210807190131.2bm24acbebl4wl6i@alap3.anarazel.de
4 years ago
/* Do local initialization of storage and buffer managers */
InitSync();
smgrinit();
InitBufferPoolAccess();
Move temporary file cleanup to before_shmem_exit(). As reported by a few OSX buildfarm animals there exist at least one path where temporary files exist during AtProcExit_Files() processing. As temporary file cleanup causes pgstat reporting, the assertions added in ee3f8d3d3ae caused failures. This is not an OSX specific issue, we were just lucky that timing on OSX reliably triggered the problem. The known way to cause this is a FATAL error during perform_base_backup() with a MANIFEST used - adding an elog(FATAL) after InitializeBackupManifest() reliably reproduces the problem in isolation. The problem is that the temporary file created in InitializeBackupManifest() is not cleaned up via resource owner cleanup as WalSndResourceCleanup() currently is only used for non-FATAL errors. That then allows to reach AtProcExit_Files() with existing temporary files, causing the assertion failure. To fix this problem, move temporary file cleanup to a before_shmem_exit() hook and add assertions ensuring that no temporary files are created before / after temporary file management has been initialized / shut down. The cleanest way to do so seems to be to split fd.c initialization into two, one for plain file access and one for temporary file access. Right now there's no need to perform further fd.c cleanup during process exit, so I just renamed AtProcExit_Files() to BeforeShmemExit_Files(). Alternatively we could perform another pass through the files to check that no temporary files exist, but the added assertions seem to provide enough protection against that. It might turn out that the assertions added in ee3f8d3d3ae will cause too much noise - in that case we'll have to downgrade them to a WARNING, at least temporarily. This commit is not necessarily the best approach to address this issue, but it should resolve the buildfarm failures. We can revise later. Author: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/20210807190131.2bm24acbebl4wl6i@alap3.anarazel.de
4 years ago
/*
* Initialize temporary file access after pgstat, so that the temporary
Move temporary file cleanup to before_shmem_exit(). As reported by a few OSX buildfarm animals there exist at least one path where temporary files exist during AtProcExit_Files() processing. As temporary file cleanup causes pgstat reporting, the assertions added in ee3f8d3d3ae caused failures. This is not an OSX specific issue, we were just lucky that timing on OSX reliably triggered the problem. The known way to cause this is a FATAL error during perform_base_backup() with a MANIFEST used - adding an elog(FATAL) after InitializeBackupManifest() reliably reproduces the problem in isolation. The problem is that the temporary file created in InitializeBackupManifest() is not cleaned up via resource owner cleanup as WalSndResourceCleanup() currently is only used for non-FATAL errors. That then allows to reach AtProcExit_Files() with existing temporary files, causing the assertion failure. To fix this problem, move temporary file cleanup to a before_shmem_exit() hook and add assertions ensuring that no temporary files are created before / after temporary file management has been initialized / shut down. The cleanest way to do so seems to be to split fd.c initialization into two, one for plain file access and one for temporary file access. Right now there's no need to perform further fd.c cleanup during process exit, so I just renamed AtProcExit_Files() to BeforeShmemExit_Files(). Alternatively we could perform another pass through the files to check that no temporary files exist, but the added assertions seem to provide enough protection against that. It might turn out that the assertions added in ee3f8d3d3ae will cause too much noise - in that case we'll have to downgrade them to a WARNING, at least temporarily. This commit is not necessarily the best approach to address this issue, but it should resolve the buildfarm failures. We can revise later. Author: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/20210807190131.2bm24acbebl4wl6i@alap3.anarazel.de
4 years ago
* file shutdown hook can report temporary file statistics.
*/
InitTemporaryFileAccess();
/*
* Initialize local buffers for WAL record construction, in case we
* ever try to insert XLOG.
*/
InitXLogInsert();
}
/* --------------------------------
* InitPostgres
* Initialize POSTGRES.
*
* The database can be specified by name, using the in_dbname parameter, or by
* OID, using the dboid parameter. In the latter case, the actual database
* name can be returned to the caller in out_dbname. If out_dbname isn't
* NULL, it must point to a buffer of size NAMEDATALEN.
*
* Similarly, the username can be passed by name, using the username parameter,
* or by OID using the useroid parameter.
*
* In bootstrap mode no parameters are used. The autovacuum launcher process
* doesn't use any parameters either, because it only goes far enough to be
* able to read pg_database; it doesn't connect to any particular database.
* In walsender mode only username is used.
*
* As of PostgreSQL 8.2, we expect InitProcess() was already called, so we
* already have a PGPROC struct ... but it's not completely filled in yet.
*
* Note:
* Be very careful with the order of calls in the InitPostgres function.
* --------------------------------
*/
void
InitPostgres(const char *in_dbname, Oid dboid, const char *username,
Oid useroid, char *out_dbname, bool override_allow_connections)
{
bool bootstrap = IsBootstrapProcessingMode();
bool am_superuser;
char *fullpath;
char dbname[NAMEDATALEN];
elog(DEBUG3, "InitPostgres");
/*
* Add my PGPROC struct to the ProcArray.
*
* Once I have done this, I am visible to other backends!
*/
InitProcessPhase2();
/*
* Initialize my entry in the shared-invalidation manager's array of
* per-backend data.
*
* Sets up MyBackendId, a unique backend identifier.
*/
MyBackendId = InvalidBackendId;
Allow read only connections during recovery, known as Hot Standby. Enabled by recovery_connections = on (default) and forcing archive recovery using a recovery.conf. Recovery processing now emulates the original transactions as they are replayed, providing full locking and MVCC behaviour for read only queries. Recovery must enter consistent state before connections are allowed, so there is a delay, typically short, before connections succeed. Replay of recovering transactions can conflict and in some cases deadlock with queries during recovery; these result in query cancellation after max_standby_delay seconds have expired. Infrastructure changes have minor effects on normal running, though introduce four new types of WAL record. New test mode "make standbycheck" allows regression tests of static command behaviour on a standby server while in recovery. Typical and extreme dynamic behaviours have been checked via code inspection and manual testing. Few port specific behaviours have been utilised, though primary testing has been on Linux only so far. This commit is the basic patch. Additional changes will follow in this release to enhance some aspects of behaviour, notably improved handling of conflicts, deadlock detection and query cancellation. Changes to VACUUM FULL are also required. Simon Riggs, with significant and lengthy review by Heikki Linnakangas, including streamlined redesign of snapshot creation and two-phase commit. Important contributions from Florian Pflug, Mark Kirkwood, Merlin Moncure, Greg Stark, Gianni Ciolli, Gabriele Bartolini, Hannu Krosing, Robert Haas, Tatsuo Ishii, Hiroyuki Yamada plus support and feedback from many other community members.
16 years ago
SharedInvalBackendInit(false);
if (MyBackendId > MaxBackends || MyBackendId <= 0)
elog(FATAL, "bad backend ID: %d", MyBackendId);
/* Now that we have a BackendId, we can participate in ProcSignal */
ProcSignalInit(MyBackendId);
/*
* Also set up timeout handlers needed for backend operation. We need
* these in every case except bootstrap.
*/
if (!bootstrap)
{
Move deadlock and other interrupt handling in proc.c out of signal handlers. Deadlock checking was performed inside signal handlers up to now. While it's a remarkable feat to have made this work reliably, it's quite complex to understand why that is the case. Partially it worked due to the assumption that semaphores are signal safe - which is not actually documented to be the case for sysv semaphores. The reason we had to rely on performing this work inside signal handlers is that semaphores aren't guaranteed to be interruptable by signals on all platforms. But now that latches provide a somewhat similar API, which actually has the guarantee of being interruptible, we can avoid doing so. Signalling between ProcSleep, ProcWakeup, ProcWaitForSignal and ProcSendSignal is now done using latches. This increases the likelihood of spurious wakeups. As spurious wakeup already were possible and aren't likely to be frequent enough to be an actual problem, this seems acceptable. This change would allow for further simplification of the deadlock checking, now that it doesn't have to run in a signal handler. But even if I were motivated to do so right now, it would still be better to do that separately. Such a cleanup shouldn't have to be reviewed a the same time as the more fundamental changes in this commit. There is one possible usability regression due to this commit. Namely it is more likely than before that log_lock_waits messages are output more than once. Reviewed-By: Heikki Linnakangas
11 years ago
RegisterTimeout(DEADLOCK_TIMEOUT, CheckDeadLockAlert);
RegisterTimeout(STATEMENT_TIMEOUT, StatementTimeoutHandler);
RegisterTimeout(LOCK_TIMEOUT, LockTimeoutHandler);
RegisterTimeout(IDLE_IN_TRANSACTION_SESSION_TIMEOUT,
IdleInTransactionSessionTimeoutHandler);
RegisterTimeout(IDLE_SESSION_TIMEOUT, IdleSessionTimeoutHandler);
RegisterTimeout(CLIENT_CONNECTION_CHECK_TIMEOUT, ClientCheckTimeoutHandler);
}
/*
* If this is either a bootstrap process nor a standalone backend, start
* up the XLOG machinery, and register to have it closed down at exit.
* In other cases, the startup process is responsible for starting up
* the XLOG machinery, and the checkpointer for closing it down.
*/
if (!IsUnderPostmaster)
{
/*
Use a ResourceOwner to track buffer pins in all cases. Historically, we've allowed auxiliary processes to take buffer pins without tracking them in a ResourceOwner. However, that creates problems for error recovery. In particular, we've seen multiple reports of assertion crashes in the startup process when it gets an error while holding a buffer pin, as for example if it gets ENOSPC during a write. In a non-assert build, the process would simply exit without releasing the pin at all. We've gotten away with that so far just because a failure exit of the startup process translates to a database crash anyhow; but any similar behavior in other aux processes could result in stuck pins and subsequent problems in vacuum. To improve this, institute a policy that we must *always* have a resowner backing any attempt to pin a buffer, which we can enforce just by removing the previous special-case code in resowner.c. Add infrastructure to make it easy to create a process-lifespan AuxProcessResourceOwner and clear out its contents at appropriate times. Replace existing ad-hoc resowner management in bgwriter.c and other aux processes with that. (Thus, while the startup process gains a resowner where it had none at all before, some other aux process types are replacing an ad-hoc resowner with this code.) Also use the AuxProcessResourceOwner to manage buffer pins taken during StartupXLOG and ShutdownXLOG, even when those are being run in a bootstrap process or a standalone backend rather than a true auxiliary process. In passing, remove some other ad-hoc resource owner creations that had gotten cargo-culted into various other places. As far as I can tell that was all unnecessary, and if it had been necessary it was incomplete, due to lacking any provision for clearing those resowners later. (Also worth noting in this connection is that a process that hasn't called InitBufferPoolBackend has no business accessing buffers; so there's more to do than just add the resowner if we want to touch buffers in processes not covered by this patch.) Although this fixes a very old bug, no back-patch, because there's no evidence of any significant problem in non-assert builds. Patch by me, pursuant to a report from Justin Pryzby. Thanks to Robert Haas and Kyotaro Horiguchi for reviews. Discussion: https://postgr.es/m/20180627233939.GA10276@telsasoft.com
7 years ago
* We don't yet have an aux-process resource owner, but StartupXLOG
* and ShutdownXLOG will need one. Hence, create said resource owner
* (and register a callback to clean it up after ShutdownXLOG runs).
*/
Use a ResourceOwner to track buffer pins in all cases. Historically, we've allowed auxiliary processes to take buffer pins without tracking them in a ResourceOwner. However, that creates problems for error recovery. In particular, we've seen multiple reports of assertion crashes in the startup process when it gets an error while holding a buffer pin, as for example if it gets ENOSPC during a write. In a non-assert build, the process would simply exit without releasing the pin at all. We've gotten away with that so far just because a failure exit of the startup process translates to a database crash anyhow; but any similar behavior in other aux processes could result in stuck pins and subsequent problems in vacuum. To improve this, institute a policy that we must *always* have a resowner backing any attempt to pin a buffer, which we can enforce just by removing the previous special-case code in resowner.c. Add infrastructure to make it easy to create a process-lifespan AuxProcessResourceOwner and clear out its contents at appropriate times. Replace existing ad-hoc resowner management in bgwriter.c and other aux processes with that. (Thus, while the startup process gains a resowner where it had none at all before, some other aux process types are replacing an ad-hoc resowner with this code.) Also use the AuxProcessResourceOwner to manage buffer pins taken during StartupXLOG and ShutdownXLOG, even when those are being run in a bootstrap process or a standalone backend rather than a true auxiliary process. In passing, remove some other ad-hoc resource owner creations that had gotten cargo-culted into various other places. As far as I can tell that was all unnecessary, and if it had been necessary it was incomplete, due to lacking any provision for clearing those resowners later. (Also worth noting in this connection is that a process that hasn't called InitBufferPoolBackend has no business accessing buffers; so there's more to do than just add the resowner if we want to touch buffers in processes not covered by this patch.) Although this fixes a very old bug, no back-patch, because there's no evidence of any significant problem in non-assert builds. Patch by me, pursuant to a report from Justin Pryzby. Thanks to Robert Haas and Kyotaro Horiguchi for reviews. Discussion: https://postgr.es/m/20180627233939.GA10276@telsasoft.com
7 years ago
CreateAuxProcessResourceOwner();
StartupXLOG();
Use a ResourceOwner to track buffer pins in all cases. Historically, we've allowed auxiliary processes to take buffer pins without tracking them in a ResourceOwner. However, that creates problems for error recovery. In particular, we've seen multiple reports of assertion crashes in the startup process when it gets an error while holding a buffer pin, as for example if it gets ENOSPC during a write. In a non-assert build, the process would simply exit without releasing the pin at all. We've gotten away with that so far just because a failure exit of the startup process translates to a database crash anyhow; but any similar behavior in other aux processes could result in stuck pins and subsequent problems in vacuum. To improve this, institute a policy that we must *always* have a resowner backing any attempt to pin a buffer, which we can enforce just by removing the previous special-case code in resowner.c. Add infrastructure to make it easy to create a process-lifespan AuxProcessResourceOwner and clear out its contents at appropriate times. Replace existing ad-hoc resowner management in bgwriter.c and other aux processes with that. (Thus, while the startup process gains a resowner where it had none at all before, some other aux process types are replacing an ad-hoc resowner with this code.) Also use the AuxProcessResourceOwner to manage buffer pins taken during StartupXLOG and ShutdownXLOG, even when those are being run in a bootstrap process or a standalone backend rather than a true auxiliary process. In passing, remove some other ad-hoc resource owner creations that had gotten cargo-culted into various other places. As far as I can tell that was all unnecessary, and if it had been necessary it was incomplete, due to lacking any provision for clearing those resowners later. (Also worth noting in this connection is that a process that hasn't called InitBufferPoolBackend has no business accessing buffers; so there's more to do than just add the resowner if we want to touch buffers in processes not covered by this patch.) Although this fixes a very old bug, no back-patch, because there's no evidence of any significant problem in non-assert builds. Patch by me, pursuant to a report from Justin Pryzby. Thanks to Robert Haas and Kyotaro Horiguchi for reviews. Discussion: https://postgr.es/m/20180627233939.GA10276@telsasoft.com
7 years ago
/* Release (and warn about) any buffer pins leaked in StartupXLOG */
ReleaseAuxProcessResources(true);
/* Reset CurrentResourceOwner to nothing for the moment */
CurrentResourceOwner = NULL;
/*
* Use before_shmem_exit() so that ShutdownXLOG() can rely on DSM
* segments etc to work (which in turn is required for pgstats).
*/
before_shmem_exit(ShutdownXLOG, 0);
}
/*
* Initialize the relation cache and the system catalog caches. Note that
* no catalog access happens here; we only set up the hashtable structure.
* We must do this before starting a transaction because transaction abort
* would try to touch these hashtables.
*/
RelationCacheInitialize();
InitCatalogCache();
InitPlanCache();
/* Initialize portal manager */
EnablePortalManager();
/* Initialize status reporting */
pgstat_beinit();
/*
* Load relcache entries for the shared system catalogs. This must create
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
* at least entries for pg_database and catalogs used for authentication.
*/
RelationCacheInitializePhase2();
/*
* Set up process-exit callback to do pre-shutdown cleanup. This is the
* one of the first before_shmem_exit callbacks we register; thus, this
* will be one the last things we do before low-level modules like the
* buffer manager begin to close down. We need to have this in place
* before we begin our first transaction --- if we fail during the
* initialization transaction, as is entirely possible, we need the
* AbortTransaction call to clean up.
*/
before_shmem_exit(ShutdownPostgres, 0);
/* The autovacuum launcher is done here */
if (IsAutoVacuumLauncherProcess())
{
/* report this backend in the PgBackendStatus array */
pgstat_bestart();
return;
}
/*
* Start a new transaction here before first access to db, and get a
* snapshot. We don't have a use for the snapshot itself, but we're
* interested in the secondary effect that it sets RecentGlobalXmin. (This
* is critical for anything that reads heap pages, because HOT may decide
* to prune them even if the process doesn't attempt to modify any
* tuples.)
snapshot scalability: Don't compute global horizons while building snapshots. To make GetSnapshotData() more scalable, it cannot not look at at each proc's xmin: While snapshot contents do not need to change whenever a read-only transaction commits or a snapshot is released, a proc's xmin is modified in those cases. The frequency of xmin modifications leads to, particularly on higher core count systems, many cache misses inside GetSnapshotData(), despite the data underlying a snapshot not changing. That is the most significant source of GetSnapshotData() scaling poorly on larger systems. Without accessing xmins, GetSnapshotData() cannot calculate accurate horizons / thresholds as it has so far. But we don't really have to: The horizons don't actually change that much between GetSnapshotData() calls. Nor are the horizons actually used every time a snapshot is built. The trick this commit introduces is to delay computation of accurate horizons until there use and using horizon boundaries to determine whether accurate horizons need to be computed. The use of RecentGlobal[Data]Xmin to decide whether a row version could be removed has been replaces with new GlobalVisTest* functions. These use two thresholds to determine whether a row can be pruned: 1) definitely_needed, indicating that rows deleted by XIDs >= definitely_needed are definitely still visible. 2) maybe_needed, indicating that rows deleted by XIDs < maybe_needed can definitely be removed GetSnapshotData() updates definitely_needed to be the xmin of the computed snapshot. When testing whether a row can be removed (with GlobalVisTestIsRemovableXid()) and the tested XID falls in between the two (i.e. XID >= maybe_needed && XID < definitely_needed) the boundaries can be recomputed to be more accurate. As it is not cheap to compute accurate boundaries, we limit the number of times that happens in short succession. As the boundaries used by GlobalVisTestIsRemovableXid() are never reset (with maybe_needed updated by GetSnapshotData()), it is likely that further test can benefit from an earlier computation of accurate horizons. To avoid regressing performance when old_snapshot_threshold is set (as that requires an accurate horizon to be computed), heap_page_prune_opt() doesn't unconditionally call TransactionIdLimitedForOldSnapshots() anymore. Both the computation of the limited horizon, and the triggering of errors (with SetOldSnapshotThresholdTimestamp()) is now only done when necessary to remove tuples. This commit just removes the accesses to PGXACT->xmin from GetSnapshotData(), but other members of PGXACT residing in the same cache line are accessed. Therefore this in itself does not result in a significant improvement. Subsequent commits will take advantage of the fact that GetSnapshotData() now does not need to access xmins anymore. Note: This contains a workaround in heap_page_prune_opt() to keep the snapshot_too_old tests working. While that workaround is ugly, the tests currently are not meaningful, and it seems best to address them separately. Author: Andres Freund <andres@anarazel.de> Reviewed-By: Robert Haas <robertmhaas@gmail.com> Reviewed-By: Thomas Munro <thomas.munro@gmail.com> Reviewed-By: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/20200301083601.ews6hz5dduc3w2se@alap3.anarazel.de
5 years ago
*
* FIXME: This comment is inaccurate / the code buggy. A snapshot that is
* not pushed/active does not reliably prevent HOT pruning (->xmin could
* e.g. be cleared when cache invalidations are processed).
*/
if (!bootstrap)
{
/* statement_timestamp must be set for timeouts to work correctly */
SetCurrentStatementStartTimestamp();
StartTransactionCommand();
/*
* transaction_isolation will have been set to the default by the
* above. If the default is "serializable", and we are in hot
* standby, we will fail if we don't change it to something lower.
* Fortunately, "read committed" is plenty good enough.
*/
XactIsoLevel = XACT_READ_COMMITTED;
(void) GetTransactionSnapshot();
}
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
/*
* Perform client authentication if necessary, then figure out our
* postgres user ID, and see if we are a superuser.
*
* In standalone mode and in autovacuum worker processes, we use a fixed
* ID, otherwise we figure it out from the authenticated user name.
*/
if (bootstrap || IsAutoVacuumWorkerProcess())
{
InitializeSessionUserIdStandalone();
am_superuser = true;
}
else if (!IsUnderPostmaster)
{
InitializeSessionUserIdStandalone();
am_superuser = true;
if (!ThereIsAtLeastOneRole())
ereport(WARNING,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("no roles are defined in this database system"),
errhint("You should immediately run CREATE USER \"%s\" SUPERUSER;.",
username != NULL ? username : "postgres")));
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
}
Background worker processes Background workers are postmaster subprocesses that run arbitrary user-specified code. They can request shared memory access as well as backend database connections; or they can just use plain libpq frontend database connections. Modules listed in shared_preload_libraries can register background workers in their _PG_init() function; this is early enough that it's not necessary to provide an extra GUC option, because the necessary extra resources can be allocated early on. Modules can install more than one bgworker, if necessary. Care is taken that these extra processes do not interfere with other postmaster tasks: only one such process is started on each ServerLoop iteration. This means a large number of them could be waiting to be started up and postmaster is still able to quickly service external connection requests. Also, shutdown sequence should not be impacted by a worker process that's reasonably well behaved (i.e. promptly responds to termination signals.) The current implementation lets worker processes specify their start time, i.e. at what point in the server startup process they are to be started: right after postmaster start (in which case they mustn't ask for shared memory access), when consistent state has been reached (useful during recovery in a HOT standby server), or when recovery has terminated (i.e. when normal backends are allowed). In case of a bgworker crash, actions to take depend on registration data: if shared memory was requested, then all other connections are taken down (as well as other bgworkers), just like it were a regular backend crashing. The bgworker itself is restarted, too, within a configurable timeframe (which can be configured to be never). More features to add to this framework can be imagined without much effort, and have been discussed, but this seems good enough as a useful unit already. An elementary sample module is supplied. Author: Álvaro Herrera This patch is loosely based on prior patches submitted by KaiGai Kohei, and unsubmitted code by Simon Riggs. Reviewed by: KaiGai Kohei, Markus Wanner, Andres Freund, Heikki Linnakangas, Simon Riggs, Amit Kapila
13 years ago
else if (IsBackgroundWorker)
{
if (username == NULL && !OidIsValid(useroid))
Background worker processes Background workers are postmaster subprocesses that run arbitrary user-specified code. They can request shared memory access as well as backend database connections; or they can just use plain libpq frontend database connections. Modules listed in shared_preload_libraries can register background workers in their _PG_init() function; this is early enough that it's not necessary to provide an extra GUC option, because the necessary extra resources can be allocated early on. Modules can install more than one bgworker, if necessary. Care is taken that these extra processes do not interfere with other postmaster tasks: only one such process is started on each ServerLoop iteration. This means a large number of them could be waiting to be started up and postmaster is still able to quickly service external connection requests. Also, shutdown sequence should not be impacted by a worker process that's reasonably well behaved (i.e. promptly responds to termination signals.) The current implementation lets worker processes specify their start time, i.e. at what point in the server startup process they are to be started: right after postmaster start (in which case they mustn't ask for shared memory access), when consistent state has been reached (useful during recovery in a HOT standby server), or when recovery has terminated (i.e. when normal backends are allowed). In case of a bgworker crash, actions to take depend on registration data: if shared memory was requested, then all other connections are taken down (as well as other bgworkers), just like it were a regular backend crashing. The bgworker itself is restarted, too, within a configurable timeframe (which can be configured to be never). More features to add to this framework can be imagined without much effort, and have been discussed, but this seems good enough as a useful unit already. An elementary sample module is supplied. Author: Álvaro Herrera This patch is loosely based on prior patches submitted by KaiGai Kohei, and unsubmitted code by Simon Riggs. Reviewed by: KaiGai Kohei, Markus Wanner, Andres Freund, Heikki Linnakangas, Simon Riggs, Amit Kapila
13 years ago
{
InitializeSessionUserIdStandalone();
am_superuser = true;
}
else
{
InitializeSessionUserId(username, useroid);
Background worker processes Background workers are postmaster subprocesses that run arbitrary user-specified code. They can request shared memory access as well as backend database connections; or they can just use plain libpq frontend database connections. Modules listed in shared_preload_libraries can register background workers in their _PG_init() function; this is early enough that it's not necessary to provide an extra GUC option, because the necessary extra resources can be allocated early on. Modules can install more than one bgworker, if necessary. Care is taken that these extra processes do not interfere with other postmaster tasks: only one such process is started on each ServerLoop iteration. This means a large number of them could be waiting to be started up and postmaster is still able to quickly service external connection requests. Also, shutdown sequence should not be impacted by a worker process that's reasonably well behaved (i.e. promptly responds to termination signals.) The current implementation lets worker processes specify their start time, i.e. at what point in the server startup process they are to be started: right after postmaster start (in which case they mustn't ask for shared memory access), when consistent state has been reached (useful during recovery in a HOT standby server), or when recovery has terminated (i.e. when normal backends are allowed). In case of a bgworker crash, actions to take depend on registration data: if shared memory was requested, then all other connections are taken down (as well as other bgworkers), just like it were a regular backend crashing. The bgworker itself is restarted, too, within a configurable timeframe (which can be configured to be never). More features to add to this framework can be imagined without much effort, and have been discussed, but this seems good enough as a useful unit already. An elementary sample module is supplied. Author: Álvaro Herrera This patch is loosely based on prior patches submitted by KaiGai Kohei, and unsubmitted code by Simon Riggs. Reviewed by: KaiGai Kohei, Markus Wanner, Andres Freund, Heikki Linnakangas, Simon Riggs, Amit Kapila
13 years ago
am_superuser = superuser();
}
}
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
else
{
/* normal multiuser case */
Assert(MyProcPort != NULL);
PerformAuthentication(MyProcPort);
InitializeSessionUserId(username, useroid);
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
am_superuser = superuser();
}
/*
* If we're trying to shut down, only superusers can connect, and new
* replication connections are not allowed.
*/
if ((!am_superuser || am_walsender) &&
MyProcPort != NULL &&
Fix postmaster's behavior during smart shutdown. Up to now, upon receipt of a SIGTERM ("smart shutdown" command), the postmaster has immediately killed all "optional" background processes, and subsequently refused to launch new ones while it's waiting for foreground client processes to exit. No doubt this seemed like an OK policy at some point; but it's a pretty bad one now, because it makes for a seriously degraded environment for the remaining clients: * Parallel queries are killed, and new ones fail to launch. (And our parallel-query infrastructure utterly fails to deal with the case in a reasonable way --- it just hangs waiting for workers that are not going to arrive. There is more work needed in that area IMO.) * Autovacuum ceases to function. We can tolerate that for awhile, but if bulk-update queries continue to run in the surviving client sessions, there's eventually going to be a mess. In the worst case the system could reach a forced shutdown to prevent XID wraparound. * The bgwriter and walwriter are also stopped immediately, likely resulting in performance degradation. Hence, let's rearrange things so that the only immediate change in behavior is refusing to let in new normal connections. Once the last normal connection is gone, shut everything down as though we'd received a "fast" shutdown. To implement this, remove the PM_WAIT_BACKUP and PM_WAIT_READONLY states, instead staying in PM_RUN or PM_HOT_STANDBY while normal connections remain. A subsidiary state variable tracks whether or not we're letting in new connections in those states. This also allows having just one copy of the logic for killing child processes in smart and fast shutdown modes. I moved that logic into PostmasterStateMachine() by inventing a new state PM_STOP_BACKENDS. Back-patch to 9.6 where parallel query was added. In principle this'd be a good idea in 9.5 as well, but the risk/reward ratio is not as good there, since lack of autovacuum is not a problem during typical uses of smart shutdown. Per report from Bharath Rupireddy. Patch by me, reviewed by Thomas Munro Discussion: https://postgr.es/m/CALj2ACXAZ5vKxT9P7P89D87i3MDO9bfS+_bjMHgnWJs8uwUOOw@mail.gmail.com
5 years ago
MyProcPort->canAcceptConnections == CAC_SUPERUSER)
{
if (am_walsender)
ereport(FATAL,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("new replication connections are not allowed during database shutdown")));
else
ereport(FATAL,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to connect during database shutdown")));
}
/*
* Binary upgrades only allowed super-user connections
*/
if (IsBinaryUpgrade && !am_superuser)
{
ereport(FATAL,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to connect in binary upgrade mode")));
}
/*
* The last few connection slots are reserved for superusers. Replication
* connections are drawn from slots reserved with max_wal_senders and not
* limited by max_connections or superuser_reserved_connections.
*/
if (!am_superuser && !am_walsender &&
ReservedBackends > 0 &&
!HaveNFreeProcs(ReservedBackends))
ereport(FATAL,
(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
errmsg("remaining connection slots are reserved for non-replication superuser connections")));
/* Check replication permissions needed for walsender processes. */
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
if (am_walsender)
{
Assert(!bootstrap);
if (!superuser() && !has_rolreplication(GetUserId()))
ereport(FATAL,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser or replication role to start walsender")));
}
/*
* If this is a plain walsender only supporting physical replication, we
* don't want to connect to any particular database. Just finish the
* backend startup by processing any options from the startup packet, and
* we're done.
*/
if (am_walsender && !am_db_walsender)
{
/* process any options passed in the startup packet */
if (MyProcPort != NULL)
process_startup_options(MyProcPort, am_superuser);
/* Apply PostAuthDelay as soon as we've read all options */
if (PostAuthDelay > 0)
pg_usleep(PostAuthDelay * 1000000L);
/* initialize client encoding */
InitializeClientEncoding();
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
/* report this backend in the PgBackendStatus array */
pgstat_bestart();
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
/* close the transaction we started above */
CommitTransactionCommand();
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
return;
}
/*
* Set up the global variables holding database id and default tablespace.
* But note we won't actually try to touch the database just yet.
*
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
* We take a shortcut in the bootstrap case, otherwise we have to look up
* the db's entry in pg_database.
*/
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
if (bootstrap)
{
MyDatabaseId = TemplateDbOid;
MyDatabaseTableSpace = DEFAULTTABLESPACE_OID;
}
else if (in_dbname != NULL)
{
HeapTuple tuple;
Form_pg_database dbform;
tuple = GetDatabaseTuple(in_dbname);
if (!HeapTupleIsValid(tuple))
ereport(FATAL,
(errcode(ERRCODE_UNDEFINED_DATABASE),
errmsg("database \"%s\" does not exist", in_dbname)));
dbform = (Form_pg_database) GETSTRUCT(tuple);
Remove WITH OIDS support, change oid catalog column visibility. Previously tables declared WITH OIDS, including a significant fraction of the catalog tables, stored the oid column not as a normal column, but as part of the tuple header. This special column was not shown by default, which was somewhat odd, as it's often (consider e.g. pg_class.oid) one of the more important parts of a row. Neither pg_dump nor COPY included the contents of the oid column by default. The fact that the oid column was not an ordinary column necessitated a significant amount of special case code to support oid columns. That already was painful for the existing, but upcoming work aiming to make table storage pluggable, would have required expanding and duplicating that "specialness" significantly. WITH OIDS has been deprecated since 2005 (commit ff02d0a05280e0). Remove it. Removing includes: - CREATE TABLE and ALTER TABLE syntax for declaring the table to be WITH OIDS has been removed (WITH (oids[ = true]) will error out) - pg_dump does not support dumping tables declared WITH OIDS and will issue a warning when dumping one (and ignore the oid column). - restoring an pg_dump archive with pg_restore will warn when restoring a table with oid contents (and ignore the oid column) - COPY will refuse to load binary dump that includes oids. - pg_upgrade will error out when encountering tables declared WITH OIDS, they have to be altered to remove the oid column first. - Functionality to access the oid of the last inserted row (like plpgsql's RESULT_OID, spi's SPI_lastoid, ...) has been removed. The syntax for declaring a table WITHOUT OIDS (or WITH (oids = false) for CREATE TABLE) is still supported. While that requires a bit of support code, it seems unnecessary to break applications / dumps that do not use oids, and are explicit about not using them. The biggest user of WITH OID columns was postgres' catalog. This commit changes all 'magic' oid columns to be columns that are normally declared and stored. To reduce unnecessary query breakage all the newly added columns are still named 'oid', even if a table's column naming scheme would indicate 'reloid' or such. This obviously requires adapting a lot code, mostly replacing oid access via HeapTupleGetOid() with access to the underlying Form_pg_*->oid column. The bootstrap process now assigns oids for all oid columns in genbki.pl that do not have an explicit value (starting at the largest oid previously used), only oids assigned later by oids will be above FirstBootstrapObjectId. As the oid column now is a normal column the special bootstrap syntax for oids has been removed. Oids are not automatically assigned during insertion anymore, all backend code explicitly assigns oids with GetNewOidWithIndex(). For the rare case that insertions into the catalog via SQL are called for the new pg_nextoid() function can be used (which only works on catalog tables). The fact that oid columns on system tables are now normal columns means that they will be included in the set of columns expanded by * (i.e. SELECT * FROM pg_class will now include the table's oid, previously it did not). It'd not technically be hard to hide oid column by default, but that'd mean confusing behavior would either have to be carried forward forever, or it'd cause breakage down the line. While it's not unlikely that further adjustments are needed, the scope/invasiveness of the patch makes it worthwhile to get merge this now. It's painful to maintain externally, too complicated to commit after the code code freeze, and a dependency of a number of other patches. Catversion bump, for obvious reasons. Author: Andres Freund, with contributions by John Naylor Discussion: https://postgr.es/m/20180930034810.ywp2c7awz7opzcfr@alap3.anarazel.de
7 years ago
MyDatabaseId = dbform->oid;
MyDatabaseTableSpace = dbform->dattablespace;
/* take database name from the caller, just for paranoia */
strlcpy(dbname, in_dbname, sizeof(dbname));
}
else if (OidIsValid(dboid))
{
/* caller specified database by OID */
HeapTuple tuple;
Form_pg_database dbform;
tuple = GetDatabaseTupleByOid(dboid);
if (!HeapTupleIsValid(tuple))
ereport(FATAL,
(errcode(ERRCODE_UNDEFINED_DATABASE),
errmsg("database %u does not exist", dboid)));
dbform = (Form_pg_database) GETSTRUCT(tuple);
Remove WITH OIDS support, change oid catalog column visibility. Previously tables declared WITH OIDS, including a significant fraction of the catalog tables, stored the oid column not as a normal column, but as part of the tuple header. This special column was not shown by default, which was somewhat odd, as it's often (consider e.g. pg_class.oid) one of the more important parts of a row. Neither pg_dump nor COPY included the contents of the oid column by default. The fact that the oid column was not an ordinary column necessitated a significant amount of special case code to support oid columns. That already was painful for the existing, but upcoming work aiming to make table storage pluggable, would have required expanding and duplicating that "specialness" significantly. WITH OIDS has been deprecated since 2005 (commit ff02d0a05280e0). Remove it. Removing includes: - CREATE TABLE and ALTER TABLE syntax for declaring the table to be WITH OIDS has been removed (WITH (oids[ = true]) will error out) - pg_dump does not support dumping tables declared WITH OIDS and will issue a warning when dumping one (and ignore the oid column). - restoring an pg_dump archive with pg_restore will warn when restoring a table with oid contents (and ignore the oid column) - COPY will refuse to load binary dump that includes oids. - pg_upgrade will error out when encountering tables declared WITH OIDS, they have to be altered to remove the oid column first. - Functionality to access the oid of the last inserted row (like plpgsql's RESULT_OID, spi's SPI_lastoid, ...) has been removed. The syntax for declaring a table WITHOUT OIDS (or WITH (oids = false) for CREATE TABLE) is still supported. While that requires a bit of support code, it seems unnecessary to break applications / dumps that do not use oids, and are explicit about not using them. The biggest user of WITH OID columns was postgres' catalog. This commit changes all 'magic' oid columns to be columns that are normally declared and stored. To reduce unnecessary query breakage all the newly added columns are still named 'oid', even if a table's column naming scheme would indicate 'reloid' or such. This obviously requires adapting a lot code, mostly replacing oid access via HeapTupleGetOid() with access to the underlying Form_pg_*->oid column. The bootstrap process now assigns oids for all oid columns in genbki.pl that do not have an explicit value (starting at the largest oid previously used), only oids assigned later by oids will be above FirstBootstrapObjectId. As the oid column now is a normal column the special bootstrap syntax for oids has been removed. Oids are not automatically assigned during insertion anymore, all backend code explicitly assigns oids with GetNewOidWithIndex(). For the rare case that insertions into the catalog via SQL are called for the new pg_nextoid() function can be used (which only works on catalog tables). The fact that oid columns on system tables are now normal columns means that they will be included in the set of columns expanded by * (i.e. SELECT * FROM pg_class will now include the table's oid, previously it did not). It'd not technically be hard to hide oid column by default, but that'd mean confusing behavior would either have to be carried forward forever, or it'd cause breakage down the line. While it's not unlikely that further adjustments are needed, the scope/invasiveness of the patch makes it worthwhile to get merge this now. It's painful to maintain externally, too complicated to commit after the code code freeze, and a dependency of a number of other patches. Catversion bump, for obvious reasons. Author: Andres Freund, with contributions by John Naylor Discussion: https://postgr.es/m/20180930034810.ywp2c7awz7opzcfr@alap3.anarazel.de
7 years ago
MyDatabaseId = dbform->oid;
MyDatabaseTableSpace = dbform->dattablespace;
Assert(MyDatabaseId == dboid);
strlcpy(dbname, NameStr(dbform->datname), sizeof(dbname));
/* pass the database name back to the caller */
if (out_dbname)
strcpy(out_dbname, dbname);
}
else
{
/*
* If this is a background worker not bound to any particular
* database, we're done now. Everything that follows only makes sense
* if we are bound to a specific database. We do need to close the
* transaction we started before returning.
*/
if (!bootstrap)
{
pgstat_bestart();
CommitTransactionCommand();
}
return;
}
/*
* Now, take a writer's lock on the database we are trying to connect to.
* If there is a concurrently running DROP DATABASE on that database, this
* will block us until it finishes (and has committed its update of
* pg_database).
*
* Note that the lock is not held long, only until the end of this startup
* transaction. This is OK since we will advertise our use of the
* database in the ProcArray before dropping the lock (in fact, that's the
* next thing to do). Anyone trying a DROP DATABASE after this point will
* see us in the array once they have the lock. Ordering is important for
* this because we don't want to advertise ourselves as being in this
* database until we have the lock; otherwise we create what amounts to a
* deadlock with CountOtherDBBackends().
*
* Note: use of RowExclusiveLock here is reasonable because we envision
* our session as being a concurrent writer of the database. If we had a
* way of declaring a session as being guaranteed-read-only, we could use
* AccessShareLock for such sessions and thereby not conflict against
* CREATE DATABASE.
*/
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
if (!bootstrap)
LockSharedObject(DatabaseRelationId, MyDatabaseId, 0,
RowExclusiveLock);
/*
* Now we can mark our PGPROC entry with the database ID.
*
* We assume this is an atomic store so no lock is needed; though actually
* things would work fine even if it weren't atomic. Anyone searching the
* ProcArray for this database's ID should hold the database lock, so they
* would not be executing concurrently with this store. A process looking
* for another database's ID could in theory see a chance match if it read
* a partially-updated databaseId value; but as long as all such searches
* wait and retry, as in CountOtherDBBackends(), they will certainly see
* the correct value on their next try.
*/
MyProc->databaseId = MyDatabaseId;
/*
* We established a catalog snapshot while reading pg_authid and/or
* pg_database; but until we have set up MyDatabaseId, we won't react to
* incoming sinval messages for unshared catalogs, so we won't realize it
* if the snapshot has been invalidated. Assume it's no good anymore.
*/
InvalidateCatalogSnapshot();
/*
* Recheck pg_database to make sure the target database hasn't gone away.
* If there was a concurrent DROP DATABASE, this ensures we will die
* cleanly without creating a mess.
*/
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
if (!bootstrap)
{
HeapTuple tuple;
tuple = GetDatabaseTuple(dbname);
if (!HeapTupleIsValid(tuple) ||
Remove WITH OIDS support, change oid catalog column visibility. Previously tables declared WITH OIDS, including a significant fraction of the catalog tables, stored the oid column not as a normal column, but as part of the tuple header. This special column was not shown by default, which was somewhat odd, as it's often (consider e.g. pg_class.oid) one of the more important parts of a row. Neither pg_dump nor COPY included the contents of the oid column by default. The fact that the oid column was not an ordinary column necessitated a significant amount of special case code to support oid columns. That already was painful for the existing, but upcoming work aiming to make table storage pluggable, would have required expanding and duplicating that "specialness" significantly. WITH OIDS has been deprecated since 2005 (commit ff02d0a05280e0). Remove it. Removing includes: - CREATE TABLE and ALTER TABLE syntax for declaring the table to be WITH OIDS has been removed (WITH (oids[ = true]) will error out) - pg_dump does not support dumping tables declared WITH OIDS and will issue a warning when dumping one (and ignore the oid column). - restoring an pg_dump archive with pg_restore will warn when restoring a table with oid contents (and ignore the oid column) - COPY will refuse to load binary dump that includes oids. - pg_upgrade will error out when encountering tables declared WITH OIDS, they have to be altered to remove the oid column first. - Functionality to access the oid of the last inserted row (like plpgsql's RESULT_OID, spi's SPI_lastoid, ...) has been removed. The syntax for declaring a table WITHOUT OIDS (or WITH (oids = false) for CREATE TABLE) is still supported. While that requires a bit of support code, it seems unnecessary to break applications / dumps that do not use oids, and are explicit about not using them. The biggest user of WITH OID columns was postgres' catalog. This commit changes all 'magic' oid columns to be columns that are normally declared and stored. To reduce unnecessary query breakage all the newly added columns are still named 'oid', even if a table's column naming scheme would indicate 'reloid' or such. This obviously requires adapting a lot code, mostly replacing oid access via HeapTupleGetOid() with access to the underlying Form_pg_*->oid column. The bootstrap process now assigns oids for all oid columns in genbki.pl that do not have an explicit value (starting at the largest oid previously used), only oids assigned later by oids will be above FirstBootstrapObjectId. As the oid column now is a normal column the special bootstrap syntax for oids has been removed. Oids are not automatically assigned during insertion anymore, all backend code explicitly assigns oids with GetNewOidWithIndex(). For the rare case that insertions into the catalog via SQL are called for the new pg_nextoid() function can be used (which only works on catalog tables). The fact that oid columns on system tables are now normal columns means that they will be included in the set of columns expanded by * (i.e. SELECT * FROM pg_class will now include the table's oid, previously it did not). It'd not technically be hard to hide oid column by default, but that'd mean confusing behavior would either have to be carried forward forever, or it'd cause breakage down the line. While it's not unlikely that further adjustments are needed, the scope/invasiveness of the patch makes it worthwhile to get merge this now. It's painful to maintain externally, too complicated to commit after the code code freeze, and a dependency of a number of other patches. Catversion bump, for obvious reasons. Author: Andres Freund, with contributions by John Naylor Discussion: https://postgr.es/m/20180930034810.ywp2c7awz7opzcfr@alap3.anarazel.de
7 years ago
MyDatabaseId != ((Form_pg_database) GETSTRUCT(tuple))->oid ||
MyDatabaseTableSpace != ((Form_pg_database) GETSTRUCT(tuple))->dattablespace)
ereport(FATAL,
(errcode(ERRCODE_UNDEFINED_DATABASE),
errmsg("database \"%s\" does not exist", dbname),
errdetail("It seems to have just been dropped or renamed.")));
}
/*
* Now we should be able to access the database directory safely. Verify
* it's there and looks reasonable.
*/
fullpath = GetDatabasePath(MyDatabaseId, MyDatabaseTableSpace);
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
if (!bootstrap)
{
if (access(fullpath, F_OK) == -1)
{
if (errno == ENOENT)
ereport(FATAL,
(errcode(ERRCODE_UNDEFINED_DATABASE),
errmsg("database \"%s\" does not exist",
dbname),
errdetail("The database subdirectory \"%s\" is missing.",
fullpath)));
else
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not access directory \"%s\": %m",
fullpath)));
}
ValidatePgVersion(fullpath);
}
SetDatabasePath(fullpath);
/*
* It's now possible to do real access to the system catalogs.
*
* Load relcache entries for the system catalogs. This must create at
* least the minimum set of "nailed-in" cache entries.
*/
RelationCacheInitializePhase3();
/* set up ACL framework (so CheckMyDatabase can check permissions) */
initialize_acl();
/*
* Re-read the pg_database row for our database, check permissions and set
* up database-specific GUC settings. We can't do this until all the
* database-access infrastructure is up. (Also, it wants to know if the
* user is a superuser, so the above stuff has to happen first.)
*/
Arrange for client authentication to occur before we select a specific database to connect to. This is necessary for the walsender code to work properly (it was previously using an untenable assumption that template1 would always be available to connect to). This also gets rid of a small security shortcoming that was introduced in the original patch to eliminate the flat authentication files: before, you could find out whether or not the requested database existed even if you couldn't pass the authentication checks. The changes needed to support this are mainly just to treat pg_authid and pg_auth_members as nailed relations, so that we can read them without having to be able to locate real pg_class entries for them. This mechanism was already debugged for pg_database, but we hadn't recognized the value of applying it to those catalogs too. Since the current code doesn't have support for accessing toast tables before we've brought up all of the relcache, remove pg_authid's toast table to ensure that no one can store an out-of-line toasted value of rolpassword. The case seems quite unlikely to occur in practice, and was effectively unsupported anyway in the old "flatfiles" implementation. Update genbki.pl to actually implement the same rules as bootstrap.c does for not-nullability of catalog columns. The previous coding was a bit cheesy but worked all right for the previous set of bootstrap catalogs. It does not work for pg_authid, where rolvaliduntil needs to be nullable. Initdb forced due to minor catalog changes (mainly the toast table removal).
15 years ago
if (!bootstrap)
CheckMyDatabase(dbname, am_superuser, override_allow_connections);
/*
* Now process any command-line switches and any additional GUC variable
* settings passed in the startup packet. We couldn't do this before
* because we didn't know if client is a superuser.
*/
if (MyProcPort != NULL)
process_startup_options(MyProcPort, am_superuser);
/* Process pg_db_role_setting options */
process_settings(MyDatabaseId, GetSessionUserId());
/* Apply PostAuthDelay as soon as we've read all options */
if (PostAuthDelay > 0)
pg_usleep(PostAuthDelay * 1000000L);
/*
* Initialize various default states that can't be set up until we've
* selected the active user and gotten the right GUC settings.
*/
/* set default namespace search path */
InitializeSearchPath();
/* initialize client encoding */
InitializeClientEncoding();
/* Initialize this backend's session state. */
InitializeSession();
/* report this backend in the PgBackendStatus array */
if (!bootstrap)
pgstat_bestart();
/* close the transaction we started above */
if (!bootstrap)
CommitTransactionCommand();
}
/*
* Process any command-line switches and any additional GUC variable
* settings passed in the startup packet.
*/
static void
process_startup_options(Port *port, bool am_superuser)
{
GucContext gucctx;
ListCell *gucopts;
gucctx = am_superuser ? PGC_SU_BACKEND : PGC_BACKEND;
/*
* First process any command-line switches that were included in the
* startup packet, if we are in a regular backend.
*/
if (port->cmdline_options != NULL)
{
/*
* The maximum possible number of commandline arguments that could
* come from port->cmdline_options is (strlen + 1) / 2; see
* pg_split_opts().
*/
char **av;
int maxac;
int ac;
maxac = 2 + (strlen(port->cmdline_options) + 1) / 2;
av = (char **) palloc(maxac * sizeof(char *));
ac = 0;
av[ac++] = "postgres";
pg_split_opts(av, &ac, port->cmdline_options);
av[ac] = NULL;
Assert(ac < maxac);
(void) process_postgres_switches(ac, av, gucctx, NULL);
}
/*
* Process any additional GUC variable settings passed in startup packet.
* These are handled exactly like command-line variables.
*/
gucopts = list_head(port->guc_options);
while (gucopts)
{
char *name;
char *value;
name = lfirst(gucopts);
Represent Lists as expansible arrays, not chains of cons-cells. Originally, Postgres Lists were a more or less exact reimplementation of Lisp lists, which consist of chains of separately-allocated cons cells, each having a value and a next-cell link. We'd hacked that once before (commit d0b4399d8) to add a separate List header, but the data was still in cons cells. That makes some operations -- notably list_nth() -- O(N), and it's bulky because of the next-cell pointers and per-cell palloc overhead, and it's very cache-unfriendly if the cons cells end up scattered around rather than being adjacent. In this rewrite, we still have List headers, but the data is in a resizable array of values, with no next-cell links. Now we need at most two palloc's per List, and often only one, since we can allocate some values in the same palloc call as the List header. (Of course, extending an existing List may require repalloc's to enlarge the array. But this involves just O(log N) allocations not O(N).) Of course this is not without downsides. The key difficulty is that addition or deletion of a list entry may now cause other entries to move, which it did not before. For example, that breaks foreach() and sister macros, which historically used a pointer to the current cons-cell as loop state. We can repair those macros transparently by making their actual loop state be an integer list index; the exposed "ListCell *" pointer is no longer state carried across loop iterations, but is just a derived value. (In practice, modern compilers can optimize things back to having just one loop state value, at least for simple cases with inline loop bodies.) In principle, this is a semantics change for cases where the loop body inserts or deletes list entries ahead of the current loop index; but I found no such cases in the Postgres code. The change is not at all transparent for code that doesn't use foreach() but chases lists "by hand" using lnext(). The largest share of such code in the backend is in loops that were maintaining "prev" and "next" variables in addition to the current-cell pointer, in order to delete list cells efficiently using list_delete_cell(). However, we no longer need a previous-cell pointer to delete a list cell efficiently. Keeping a next-cell pointer doesn't work, as explained above, but we can improve matters by changing such code to use a regular foreach() loop and then using the new macro foreach_delete_current() to delete the current cell. (This macro knows how to update the associated foreach loop's state so that no cells will be missed in the traversal.) There remains a nontrivial risk of code assuming that a ListCell * pointer will remain good over an operation that could now move the list contents. To help catch such errors, list.c can be compiled with a new define symbol DEBUG_LIST_MEMORY_USAGE that forcibly moves list contents whenever that could possibly happen. This makes list operations significantly more expensive so it's not normally turned on (though it is on by default if USE_VALGRIND is on). There are two notable API differences from the previous code: * lnext() now requires the List's header pointer in addition to the current cell's address. * list_delete_cell() no longer requires a previous-cell argument. These changes are somewhat unfortunate, but on the other hand code using either function needs inspection to see if it is assuming anything it shouldn't, so it's not all bad. Programmers should be aware of these significant performance changes: * list_nth() and related functions are now O(1); so there's no major access-speed difference between a list and an array. * Inserting or deleting a list element now takes time proportional to the distance to the end of the list, due to moving the array elements. (However, it typically *doesn't* require palloc or pfree, so except in long lists it's probably still faster than before.) Notably, lcons() used to be about the same cost as lappend(), but that's no longer true if the list is long. Code that uses lcons() and list_delete_first() to maintain a stack might usefully be rewritten to push and pop at the end of the list rather than the beginning. * There are now list_insert_nth...() and list_delete_nth...() functions that add or remove a list cell identified by index. These have the data-movement penalty explained above, but there's no search penalty. * list_concat() and variants now copy the second list's data into storage belonging to the first list, so there is no longer any sharing of cells between the input lists. The second argument is now declared "const List *" to reflect that it isn't changed. This patch just does the minimum needed to get the new implementation in place and fix bugs exposed by the regression tests. As suggested by the foregoing, there's a fair amount of followup work remaining to do. Also, the ENABLE_LIST_COMPAT macros are finally removed in this commit. Code using those should have been gone a dozen years ago. Patch by me; thanks to David Rowley, Jesper Pedersen, and others for review. Discussion: https://postgr.es/m/11587.1550975080@sss.pgh.pa.us
6 years ago
gucopts = lnext(port->guc_options, gucopts);
value = lfirst(gucopts);
Represent Lists as expansible arrays, not chains of cons-cells. Originally, Postgres Lists were a more or less exact reimplementation of Lisp lists, which consist of chains of separately-allocated cons cells, each having a value and a next-cell link. We'd hacked that once before (commit d0b4399d8) to add a separate List header, but the data was still in cons cells. That makes some operations -- notably list_nth() -- O(N), and it's bulky because of the next-cell pointers and per-cell palloc overhead, and it's very cache-unfriendly if the cons cells end up scattered around rather than being adjacent. In this rewrite, we still have List headers, but the data is in a resizable array of values, with no next-cell links. Now we need at most two palloc's per List, and often only one, since we can allocate some values in the same palloc call as the List header. (Of course, extending an existing List may require repalloc's to enlarge the array. But this involves just O(log N) allocations not O(N).) Of course this is not without downsides. The key difficulty is that addition or deletion of a list entry may now cause other entries to move, which it did not before. For example, that breaks foreach() and sister macros, which historically used a pointer to the current cons-cell as loop state. We can repair those macros transparently by making their actual loop state be an integer list index; the exposed "ListCell *" pointer is no longer state carried across loop iterations, but is just a derived value. (In practice, modern compilers can optimize things back to having just one loop state value, at least for simple cases with inline loop bodies.) In principle, this is a semantics change for cases where the loop body inserts or deletes list entries ahead of the current loop index; but I found no such cases in the Postgres code. The change is not at all transparent for code that doesn't use foreach() but chases lists "by hand" using lnext(). The largest share of such code in the backend is in loops that were maintaining "prev" and "next" variables in addition to the current-cell pointer, in order to delete list cells efficiently using list_delete_cell(). However, we no longer need a previous-cell pointer to delete a list cell efficiently. Keeping a next-cell pointer doesn't work, as explained above, but we can improve matters by changing such code to use a regular foreach() loop and then using the new macro foreach_delete_current() to delete the current cell. (This macro knows how to update the associated foreach loop's state so that no cells will be missed in the traversal.) There remains a nontrivial risk of code assuming that a ListCell * pointer will remain good over an operation that could now move the list contents. To help catch such errors, list.c can be compiled with a new define symbol DEBUG_LIST_MEMORY_USAGE that forcibly moves list contents whenever that could possibly happen. This makes list operations significantly more expensive so it's not normally turned on (though it is on by default if USE_VALGRIND is on). There are two notable API differences from the previous code: * lnext() now requires the List's header pointer in addition to the current cell's address. * list_delete_cell() no longer requires a previous-cell argument. These changes are somewhat unfortunate, but on the other hand code using either function needs inspection to see if it is assuming anything it shouldn't, so it's not all bad. Programmers should be aware of these significant performance changes: * list_nth() and related functions are now O(1); so there's no major access-speed difference between a list and an array. * Inserting or deleting a list element now takes time proportional to the distance to the end of the list, due to moving the array elements. (However, it typically *doesn't* require palloc or pfree, so except in long lists it's probably still faster than before.) Notably, lcons() used to be about the same cost as lappend(), but that's no longer true if the list is long. Code that uses lcons() and list_delete_first() to maintain a stack might usefully be rewritten to push and pop at the end of the list rather than the beginning. * There are now list_insert_nth...() and list_delete_nth...() functions that add or remove a list cell identified by index. These have the data-movement penalty explained above, but there's no search penalty. * list_concat() and variants now copy the second list's data into storage belonging to the first list, so there is no longer any sharing of cells between the input lists. The second argument is now declared "const List *" to reflect that it isn't changed. This patch just does the minimum needed to get the new implementation in place and fix bugs exposed by the regression tests. As suggested by the foregoing, there's a fair amount of followup work remaining to do. Also, the ENABLE_LIST_COMPAT macros are finally removed in this commit. Code using those should have been gone a dozen years ago. Patch by me; thanks to David Rowley, Jesper Pedersen, and others for review. Discussion: https://postgr.es/m/11587.1550975080@sss.pgh.pa.us
6 years ago
gucopts = lnext(port->guc_options, gucopts);
SetConfigOption(name, value, gucctx, PGC_S_CLIENT);
}
}
25 years ago
/*
* Load GUC settings from pg_db_role_setting.
*
* We try specific settings for the database/role combination, as well as
* general for this database and for this user.
*/
static void
process_settings(Oid databaseid, Oid roleid)
{
Relation relsetting;
Snapshot snapshot;
if (!IsUnderPostmaster)
return;
relsetting = table_open(DbRoleSettingRelationId, AccessShareLock);
/* read all the settings under the same snapshot for efficiency */
snapshot = RegisterSnapshot(GetCatalogSnapshot(DbRoleSettingRelationId));
/* Later settings are ignored if set earlier. */
ApplySetting(snapshot, databaseid, roleid, relsetting, PGC_S_DATABASE_USER);
ApplySetting(snapshot, InvalidOid, roleid, relsetting, PGC_S_USER);
ApplySetting(snapshot, databaseid, InvalidOid, relsetting, PGC_S_DATABASE);
ApplySetting(snapshot, InvalidOid, InvalidOid, relsetting, PGC_S_GLOBAL);
UnregisterSnapshot(snapshot);
table_close(relsetting, AccessShareLock);
}
/*
* Backend-shutdown callback. Do cleanup that we want to be sure happens
* before all the supporting modules begin to nail their doors shut via
* their own callbacks.
*
* User-level cleanup, such as temp-relation removal and UNLISTEN, happens
* via separate callbacks that execute before this one. We don't combine the
* callbacks because we still want this one to happen if the user-level
* cleanup fails.
*/
static void
ShutdownPostgres(int code, Datum arg)
{
/* Make sure we've killed any active transaction */
AbortOutOfAnyTransaction();
/*
* User locks are not released by transaction end, so be sure to release
* them explicitly.
*/
LockReleaseAll(USER_LOCKMETHOD, true);
}
/*
* STATEMENT_TIMEOUT handler: trigger a query-cancel interrupt.
*/
static void
StatementTimeoutHandler(void)
{
int sig = SIGINT;
/*
* During authentication the timeout is used to deal with
* authentication_timeout - we want to quit in response to such timeouts.
*/
if (ClientAuthInProgress)
sig = SIGTERM;
#ifdef HAVE_SETSID
/* try to signal whole process group */
kill(-MyProcPid, sig);
#endif
kill(MyProcPid, sig);
}
/*
* LOCK_TIMEOUT handler: trigger a query-cancel interrupt.
*/
static void
LockTimeoutHandler(void)
{
#ifdef HAVE_SETSID
/* try to signal whole process group */
kill(-MyProcPid, SIGINT);
#endif
kill(MyProcPid, SIGINT);
}
static void
IdleInTransactionSessionTimeoutHandler(void)
{
IdleInTransactionSessionTimeoutPending = true;
InterruptPending = true;
SetLatch(MyLatch);
}
static void
IdleSessionTimeoutHandler(void)
{
IdleSessionTimeoutPending = true;
InterruptPending = true;
SetLatch(MyLatch);
}
static void
ClientCheckTimeoutHandler(void)
{
CheckClientConnectionPending = true;
InterruptPending = true;
SetLatch(MyLatch);
}
/*
* Returns true if at least one role is defined in this database cluster.
*/
static bool
ThereIsAtLeastOneRole(void)
{
Relation pg_authid_rel;
tableam: Add and use scan APIs. Too allow table accesses to be not directly dependent on heap, several new abstractions are needed. Specifically: 1) Heap scans need to be generalized into table scans. Do this by introducing TableScanDesc, which will be the "base class" for individual AMs. This contains the AM independent fields from HeapScanDesc. The previous heap_{beginscan,rescan,endscan} et al. have been replaced with a table_ version. There's no direct replacement for heap_getnext(), as that returned a HeapTuple, which is undesirable for a other AMs. Instead there's table_scan_getnextslot(). But note that heap_getnext() lives on, it's still used widely to access catalog tables. This is achieved by new scan_begin, scan_end, scan_rescan, scan_getnextslot callbacks. 2) The portion of parallel scans that's shared between backends need to be able to do so without the user doing per-AM work. To achieve that new parallelscan_{estimate, initialize, reinitialize} callbacks are introduced, which operate on a new ParallelTableScanDesc, which again can be subclassed by AMs. As it is likely that several AMs are going to be block oriented, block oriented callbacks that can be shared between such AMs are provided and used by heap. table_block_parallelscan_{estimate, intiialize, reinitialize} as callbacks, and table_block_parallelscan_{nextpage, init} for use in AMs. These operate on a ParallelBlockTableScanDesc. 3) Index scans need to be able to access tables to return a tuple, and there needs to be state across individual accesses to the heap to store state like buffers. That's now handled by introducing a sort-of-scan IndexFetchTable, which again is intended to be subclassed by individual AMs (for heap IndexFetchHeap). The relevant callbacks for an AM are index_fetch_{end, begin, reset} to create the necessary state, and index_fetch_tuple to retrieve an indexed tuple. Note that index_fetch_tuple implementations need to be smarter than just blindly fetching the tuples for AMs that have optimizations similar to heap's HOT - the currently alive tuple in the update chain needs to be fetched if appropriate. Similar to table_scan_getnextslot(), it's undesirable to continue to return HeapTuples. Thus index_fetch_heap (might want to rename that later) now accepts a slot as an argument. Core code doesn't have a lot of call sites performing index scans without going through the systable_* API (in contrast to loads of heap_getnext calls and working directly with HeapTuples). Index scans now store the result of a search in IndexScanDesc->xs_heaptid, rather than xs_ctup->t_self. As the target is not generally a HeapTuple anymore that seems cleaner. To be able to sensible adapt code to use the above, two further callbacks have been introduced: a) slot_callbacks returns a TupleTableSlotOps* suitable for creating slots capable of holding a tuple of the AMs type. table_slot_callbacks() and table_slot_create() are based upon that, but have additional logic to deal with views, foreign tables, etc. While this change could have been done separately, nearly all the call sites that needed to be adapted for the rest of this commit also would have been needed to be adapted for table_slot_callbacks(), making separation not worthwhile. b) tuple_satisfies_snapshot checks whether the tuple in a slot is currently visible according to a snapshot. That's required as a few places now don't have a buffer + HeapTuple around, but a slot (which in heap's case internally has that information). Additionally a few infrastructure changes were needed: I) SysScanDesc, as used by systable_{beginscan, getnext} et al. now internally uses a slot to keep track of tuples. While systable_getnext() still returns HeapTuples, and will so for the foreseeable future, the index API (see 1) above) now only deals with slots. The remainder, and largest part, of this commit is then adjusting all scans in postgres to use the new APIs. Author: Andres Freund, Haribabu Kommi, Alvaro Herrera Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de https://postgr.es/m/20160812231527.GA690404@alvherre.pgsql
6 years ago
TableScanDesc scan;
bool result;
pg_authid_rel = table_open(AuthIdRelationId, AccessShareLock);
tableam: Add and use scan APIs. Too allow table accesses to be not directly dependent on heap, several new abstractions are needed. Specifically: 1) Heap scans need to be generalized into table scans. Do this by introducing TableScanDesc, which will be the "base class" for individual AMs. This contains the AM independent fields from HeapScanDesc. The previous heap_{beginscan,rescan,endscan} et al. have been replaced with a table_ version. There's no direct replacement for heap_getnext(), as that returned a HeapTuple, which is undesirable for a other AMs. Instead there's table_scan_getnextslot(). But note that heap_getnext() lives on, it's still used widely to access catalog tables. This is achieved by new scan_begin, scan_end, scan_rescan, scan_getnextslot callbacks. 2) The portion of parallel scans that's shared between backends need to be able to do so without the user doing per-AM work. To achieve that new parallelscan_{estimate, initialize, reinitialize} callbacks are introduced, which operate on a new ParallelTableScanDesc, which again can be subclassed by AMs. As it is likely that several AMs are going to be block oriented, block oriented callbacks that can be shared between such AMs are provided and used by heap. table_block_parallelscan_{estimate, intiialize, reinitialize} as callbacks, and table_block_parallelscan_{nextpage, init} for use in AMs. These operate on a ParallelBlockTableScanDesc. 3) Index scans need to be able to access tables to return a tuple, and there needs to be state across individual accesses to the heap to store state like buffers. That's now handled by introducing a sort-of-scan IndexFetchTable, which again is intended to be subclassed by individual AMs (for heap IndexFetchHeap). The relevant callbacks for an AM are index_fetch_{end, begin, reset} to create the necessary state, and index_fetch_tuple to retrieve an indexed tuple. Note that index_fetch_tuple implementations need to be smarter than just blindly fetching the tuples for AMs that have optimizations similar to heap's HOT - the currently alive tuple in the update chain needs to be fetched if appropriate. Similar to table_scan_getnextslot(), it's undesirable to continue to return HeapTuples. Thus index_fetch_heap (might want to rename that later) now accepts a slot as an argument. Core code doesn't have a lot of call sites performing index scans without going through the systable_* API (in contrast to loads of heap_getnext calls and working directly with HeapTuples). Index scans now store the result of a search in IndexScanDesc->xs_heaptid, rather than xs_ctup->t_self. As the target is not generally a HeapTuple anymore that seems cleaner. To be able to sensible adapt code to use the above, two further callbacks have been introduced: a) slot_callbacks returns a TupleTableSlotOps* suitable for creating slots capable of holding a tuple of the AMs type. table_slot_callbacks() and table_slot_create() are based upon that, but have additional logic to deal with views, foreign tables, etc. While this change could have been done separately, nearly all the call sites that needed to be adapted for the rest of this commit also would have been needed to be adapted for table_slot_callbacks(), making separation not worthwhile. b) tuple_satisfies_snapshot checks whether the tuple in a slot is currently visible according to a snapshot. That's required as a few places now don't have a buffer + HeapTuple around, but a slot (which in heap's case internally has that information). Additionally a few infrastructure changes were needed: I) SysScanDesc, as used by systable_{beginscan, getnext} et al. now internally uses a slot to keep track of tuples. While systable_getnext() still returns HeapTuples, and will so for the foreseeable future, the index API (see 1) above) now only deals with slots. The remainder, and largest part, of this commit is then adjusting all scans in postgres to use the new APIs. Author: Andres Freund, Haribabu Kommi, Alvaro Herrera Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de https://postgr.es/m/20160812231527.GA690404@alvherre.pgsql
6 years ago
scan = table_beginscan_catalog(pg_authid_rel, 0, NULL);
result = (heap_getnext(scan, ForwardScanDirection) != NULL);
tableam: Add and use scan APIs. Too allow table accesses to be not directly dependent on heap, several new abstractions are needed. Specifically: 1) Heap scans need to be generalized into table scans. Do this by introducing TableScanDesc, which will be the "base class" for individual AMs. This contains the AM independent fields from HeapScanDesc. The previous heap_{beginscan,rescan,endscan} et al. have been replaced with a table_ version. There's no direct replacement for heap_getnext(), as that returned a HeapTuple, which is undesirable for a other AMs. Instead there's table_scan_getnextslot(). But note that heap_getnext() lives on, it's still used widely to access catalog tables. This is achieved by new scan_begin, scan_end, scan_rescan, scan_getnextslot callbacks. 2) The portion of parallel scans that's shared between backends need to be able to do so without the user doing per-AM work. To achieve that new parallelscan_{estimate, initialize, reinitialize} callbacks are introduced, which operate on a new ParallelTableScanDesc, which again can be subclassed by AMs. As it is likely that several AMs are going to be block oriented, block oriented callbacks that can be shared between such AMs are provided and used by heap. table_block_parallelscan_{estimate, intiialize, reinitialize} as callbacks, and table_block_parallelscan_{nextpage, init} for use in AMs. These operate on a ParallelBlockTableScanDesc. 3) Index scans need to be able to access tables to return a tuple, and there needs to be state across individual accesses to the heap to store state like buffers. That's now handled by introducing a sort-of-scan IndexFetchTable, which again is intended to be subclassed by individual AMs (for heap IndexFetchHeap). The relevant callbacks for an AM are index_fetch_{end, begin, reset} to create the necessary state, and index_fetch_tuple to retrieve an indexed tuple. Note that index_fetch_tuple implementations need to be smarter than just blindly fetching the tuples for AMs that have optimizations similar to heap's HOT - the currently alive tuple in the update chain needs to be fetched if appropriate. Similar to table_scan_getnextslot(), it's undesirable to continue to return HeapTuples. Thus index_fetch_heap (might want to rename that later) now accepts a slot as an argument. Core code doesn't have a lot of call sites performing index scans without going through the systable_* API (in contrast to loads of heap_getnext calls and working directly with HeapTuples). Index scans now store the result of a search in IndexScanDesc->xs_heaptid, rather than xs_ctup->t_self. As the target is not generally a HeapTuple anymore that seems cleaner. To be able to sensible adapt code to use the above, two further callbacks have been introduced: a) slot_callbacks returns a TupleTableSlotOps* suitable for creating slots capable of holding a tuple of the AMs type. table_slot_callbacks() and table_slot_create() are based upon that, but have additional logic to deal with views, foreign tables, etc. While this change could have been done separately, nearly all the call sites that needed to be adapted for the rest of this commit also would have been needed to be adapted for table_slot_callbacks(), making separation not worthwhile. b) tuple_satisfies_snapshot checks whether the tuple in a slot is currently visible according to a snapshot. That's required as a few places now don't have a buffer + HeapTuple around, but a slot (which in heap's case internally has that information). Additionally a few infrastructure changes were needed: I) SysScanDesc, as used by systable_{beginscan, getnext} et al. now internally uses a slot to keep track of tuples. While systable_getnext() still returns HeapTuples, and will so for the foreseeable future, the index API (see 1) above) now only deals with slots. The remainder, and largest part, of this commit is then adjusting all scans in postgres to use the new APIs. Author: Andres Freund, Haribabu Kommi, Alvaro Herrera Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de https://postgr.es/m/20160812231527.GA690404@alvherre.pgsql
6 years ago
table_endscan(scan);
table_close(pg_authid_rel, AccessShareLock);
return result;
}