pg_wal_replay_wait() is to be used on standby and specifies waiting for
the specific WAL location to be replayed. This option is useful when
the user makes some data changes on primary and needs a guarantee to see
these changes are on standby.
The queue of waiters is stored in the shared memory as an LSN-ordered pairing
heap, where the waiter with the nearest LSN stays on the top. During
the replay of WAL, waiters whose LSNs have already been replayed are deleted
from the shared memory pairing heap and woken up by setting their latches.
pg_wal_replay_wait() needs to wait without any snapshot held. Otherwise,
the snapshot could prevent the replay of WAL records, implying a kind of
self-deadlock. This is why it is only possible to implement
pg_wal_replay_wait() as a procedure working without an active snapshot,
not a function.
Catversion is bumped.
Discussion: https://postgr.es/m/eb12f9b03851bb2583adab5df9579b4b%40postgrespro.ru
Author: Kartyshov Ivan, Alexander Korotkov
Reviewed-by: Michael Paquier, Peter Eisentraut, Dilip Kumar, Amit Kapila
Reviewed-by: Alexander Lakhin, Bharath Rupireddy, Euler Taveira
Reviewed-by: Heikki Linnakangas, Kyotaro Horiguchi
06c418e163 introduced pg_wal_replay_wait() procedure allowing to wait for
the particular LSN to be replayed on standby. The waiters were stored in
the flat array. Even though scanning small arrays is fast, that might be a
problem at scale (a lot of waiting processes).
This commit replaces the flat shared memory array with the pairing heap,
which holds the waiter with the least LSN at the top. This gives us O(log N)
complexity for both inserting and removing waiters.
Reported-by: Alvaro Herrera
Discussion: https://postgr.es/m/202404030658.hhj3vfxeyhft%40alvherre.pgsql
as determined by include-what-you-use (IWYU)
While IWYU also suggests to *add* a bunch of #include's (which is its
main purpose), this patch does not do that. In some cases, a more
specific #include replaces another less specific one.
Some manual adjustments of the automatic result:
- IWYU currently doesn't know about includes that provide global
variable declarations (like -Wmissing-variable-declarations), so
those includes are being kept manually.
- All includes for port(ability) headers are being kept for now, to
play it safe.
- No changes of catalog/pg_foo.h to catalog/pg_foo_d.h, to keep the
patch from exploding in size.
Note that this patch touches just *.c files, so nothing declared in
header files changes in hidden ways.
As a small example, in src/backend/access/transam/rmgr.c, some IWYU
pragma annotations are added to handle a special case there.
Discussion: https://www.postgresql.org/message-id/flat/af837490-6b2f-46df-ba05-37ea6a6653fc%40eisentraut.org
A recent commit added a copy_function member to the
dshash_parameters struct, but it missed updating a couple of
comments that refer to the function pointer members of this struct.
One of those comments also refers to a tranche_name member and non-
arg variants of the function pointer members, all of which were
either removed during development or removed shortly after dshash
table support was committed.
Oversights in commits 8c0d7bafad, d7694fc148, and 42a1de3013.
Discussion: https://postgr.es/m/20240227045213.GA2329190%40nathanxps13
Presently, string keys are not well-supported for dshash tables.
The dshash code always copies key_size bytes into new entries'
keys, and dshash.h only provides compare and hash functions that
forward to memcmp() and tag_hash(), both of which do not stop at
the first NUL. This means that callers must pad string keys so
that the data beyond the first NUL does not adversely affect the
results of copying, comparing, and hashing the keys.
To better support string keys in dshash tables, this commit does
a couple things:
* A new copy_function field is added to the dshash_parameters
struct. This function pointer specifies how the key should be
copied into new table entries. For example, we only want to copy
up to the first NUL byte for string keys. A dshash_memcpy()
helper function is provided and used for all existing in-tree
dshash tables without string keys.
* A set of helper functions for string keys are provided. These
helper functions forward to strcmp(), strcpy(), and
string_hash(), all of which ignore data beyond the first NUL.
This commit also adjusts the DSM registry's dshash table to use the
new helper functions for string keys.
Reviewed-by: Andy Fan
Discussion: https://postgr.es/m/20240119215941.GA1322079%40nathanxps13
Some code in DiscreteKnapsack() attempted to zero all words in a
Bitmapset by performing bms_del_members() to delete all the members from
itself before replacing those members with members from another set.
When that code was written, this was a valid way to manipulate the set
in such a way to save from palloc having to be called to allocate a new
Bitmapset. However, 00b41463c modified Bitmapsets so that an empty set is
*always* represented as NULL and this breaks the optimization as the
Bitmapset code will always pfree the memory when the set becomes empty.
Since DiscreteKnapsack() has been coded to avoid as many unneeded
allocations as possible, it seems risky to not fix this. Here we add
bms_replace_members() to effectively perform an in-place copy of another
set, reusing the memory of the existing set, when possible.
This got broken in v16, but no backpatch for now as there've been no
complaints.
Reviewed-by: Richard Guo
Discussion: https://postgr.es/m/CAApHDvoTCBkBU2PJghNOFUiO0q=QP4WAWHi5sJP6_4=b2WodrA@mail.gmail.com
There are a couple of places in frontend code that could make use
of this simple binary heap implementation. This commit makes
binaryheap usable in frontend code, much like commit 26aaf97b68 did
for StringInfo. Like StringInfo, the header file is left in lib/
to reduce the likelihood of unnecessary breakage.
The frontend version of binaryheap exposes a void *-based API since
frontend code does not have access to the Datum definitions. This
seemed like a better approach than switching all existing uses to
void * or making the Datum definitions available to frontend code.
Reviewed-by: Tom Lane, Alvaro Herrera
Discussion: https://postgr.es/m/3612876.1689443232%40sss.pgh.pa.us
In c8ad4d8166 dlist_member_check()'s arguments were made const. Unfortunately
the implementation of dlist_member_check() used dlist_foreach(), which
currently doesn't work for const lists.
As a workaround, open-code the list iteration. The other check functions
already do so.
Discussion: https://postgr.es/m/20230118182214.co7dp4oahiunwg57@awork3.anarazel.de
Const qualifiers ensure that we don't do something stupid in the
function implementation. Additionally they clarify the interface. As
an example:
void
slist_delete(slist_head *head, const slist_node *node)
Here one can instantly tell that node->next is not going to be set to
NULL. Finally, const qualifiers potentially allow the compiler to do
more optimizations. This being said, no benchmarking was done for
this patch.
The functions that return non-const pointers like slist_next_node(),
dclist_next_node() etc. are not affected by the patch intentionally.
Author: Aleksander Alekseev
Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/CAJ7c6TM2%3D08mNKD9aJg8vEY9hd%2BG4L7%2BNvh30UiNT3kShgRgNg%40mail.gmail.com
We have various requirements when using a dlist_head to keep track of the
number of items in the list. This, traditionally, has been done by
maintaining a counter variable in the calling code. Here we tidy this up
by adding "dclist", which is very similar to dlist but also keeps track of
the number of items stored in the list.
Callers may use the new dclist_count() function when they need to know how
many items are stored. Obtaining the count is an O(1) operation.
For simplicity reasons, dclist and dlist both use dlist_node as their node
type and dlist_iter/dlist_mutable_iter as their iterator type. dclists
have all of the same functionality as dlists except there is no function
named dclist_delete(). To remove an item from a list dclist_delete_from()
must be used. This requires knowing which dclist the given item is stored
in.
Additionally, here we also convert some dlists where additional code
exists to keep track of the number of items stored and to make these use
dclists instead.
Author: David Rowley
Reviewed-by: Bharath Rupireddy, Aleksander Alekseev
Discussion: https://postgr.es/m/CAApHDvrtVxr+FXEX0VbViCFKDGxA3tWDgw9oFewNXCJMmwLjLg@mail.gmail.com
Autoconf is showing its age, fewer and fewer contributors know how to wrangle
it. Recursive make has a lot of hard to resolve dependency issues and slow
incremental rebuilds. Our home-grown MSVC build system is hard to maintain for
developers not using Windows and runs tests serially. While these and other
issues could individually be addressed with incremental improvements, together
they seem best addressed by moving to a more modern build system.
After evaluating different build system choices, we chose to use meson, to a
good degree based on the adoption by other open source projects.
We decided that it's more realistic to commit a relatively early version of
the new build system and mature it in tree.
This commit adds an initial version of a meson based build system. It supports
building postgres on at least AIX, FreeBSD, Linux, macOS, NetBSD, OpenBSD,
Solaris and Windows (however only gcc is supported on aix, solaris). For
Windows/MSVC postgres can now be built with ninja (faster, particularly for
incremental builds) and msbuild (supporting the visual studio GUI, but
building slower).
Several aspects (e.g. Windows rc file generation, PGXS compatibility, LLVM
bitcode generation, documentation adjustments) are done in subsequent commits
requiring further review. Other aspects (e.g. not installing test-only
extensions) are not yet addressed.
When building on Windows with msbuild, builds are slower when using a visual
studio version older than 2019, because those versions do not support
MultiToolTask, required by meson for intra-target parallelism.
The plan is to remove the MSVC specific build system in src/tools/msvc soon
after reaching feature parity. However, we're not planning to remove the
autoconf/make build system in the near future. Likely we're going to keep at
least the parts required for PGXS to keep working around until all supported
versions build with meson.
Some initial help for postgres developers is at
https://wiki.postgresql.org/wiki/Meson
With contributions from Thomas Munro, John Naylor, Stone Tickle and others.
Author: Andres Freund <andres@anarazel.de>
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Author: Peter Eisentraut <peter@eisentraut.org>
Reviewed-By: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Discussion: https://postgr.es/m/20211012083721.hvixq4pnh2pixr3j@alap3.anarazel.de
Make sure that function declarations use names that exactly match the
corresponding names from function definitions in optimizer, parser,
utility, libpq, and "commands" code, as well as in remaining library
code. Do the same for all code related to frontend programs (with the
exception of pg_dump/pg_dumpall related code).
Like other recent commits that cleaned up function parameter names, this
commit was written with help from clang-tidy. Later commits will handle
ecpg and pg_dump/pg_dumpall.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com
Make sure that function declarations use names that exactly match the
corresponding names from function definitions in storage, catalog,
access method, executor, and logical replication code, as well as in
miscellaneous utility/library code.
Like other recent commits that cleaned up function parameter names, this
commit was written with help from clang-tidy. Later commits will do the
same for other parts of the codebase.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com
In a similar effort to f01592f91, here we're targetting fixing the
warnings where we've deemed the shadowing variable to serve a close enough
purpose to the shadowed variable just to reuse the shadowed version and
not declare the shadowing variable at all.
By my count, this takes the warning count from 106 down to 71.
Author: Justin Pryzby
Discussion: https://postgr.es/m/20220825020839.GT2342@telsasoft.com
dshash.c previously maintained flags to be able to assert that you
didn't hold any partition lock. These flags could get out of sync with
reality in error scenarios.
Get rid of all that, and make assertions about the locks themselves
instead. Since LWLockHeldByMe() loops internally, we don't want to put
that inside another loop over all partition locks. Introduce a new
debugging-only interface LWLockAnyHeldByMe() to avoid that.
This problem was noted by Tom and Andres while reviewing changes to
support the new shared memory stats system, and later showed up in
reality while working on commit 389869af.
Back-patch to 11, where dshash.c arrived.
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Reported-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Reviewed-by: Zhihong Yu <zyu@yugabyte.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20220311012712.botrpsikaufzteyt@alap3.anarazel.de
Discussion: https://postgr.es/m/CA%2BhUKGJ31Wce6HJ7xnVTKWjFUWQZPBngxfJVx4q0E98pDr3kAw%40mail.gmail.com
PostgreSQL contains the implementation of the red-black tree. The red-black
tree is the ordered data structure, and one of its advantages is the ability
to do inequality searches. This commit adds rbt_find_less() and
rbt_find_great() functions implementing these searches. While these searches
aren't yet used in the core code, they might be useful for extensions.
Discussion: https://postgr.es/m/CAGRrpzYE8-7GCoaPjOiL9T_HY605MRax-2jgTtLq236uksZ1Sw%40mail.gmail.com
Author: Steve Chavez, Alexander Korotkov
Reviewed-by: Alexander Korotkov
The previous coding of dshash_seq_next(), on the first call, accessed
status->hash_table->size_log2 without holding a partition lock and without
guaranteeing that ensure_valid_bucket_pointers() had ever been called.
That oversight turns out to not have immediately visible effects, because
bucket 0 is always in partition 0, and ensure_valid_bucket_pointers() was
called after acquiring the partition lock. However,
PARTITION_FOR_BUCKET_INDEX() with a size_log2 of 0 ends up triggering formally
undefined behaviour.
Simplify by accessing partition 0, without using PARTITION_FOR_BUCKET_INDEX().
While at it, remove dshash_get_current(), there is no convincing use
case. Also polish a few comments.
Author: Andres Freund <andres@anarazel.de>
Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/CA+hUKGL9hY_VY=+oUK+Gc1iSRx-Ls5qeYJ6q=dQVZnT3R63Taw@mail.gmail.com
Add ability to scan all entries sequentially to dshash. The interface is
similar but a bit different both from that of dynahash and simple dshash
search functions. The most significant differences is that dshash's interfac
always needs a call to dshash_seq_term when scan ends. Another is
locking. Dshash holds partition lock when returning an entry,
dshash_seq_next() also holds lock when returning an entry but callers
shouldn't release it, since the lock is essential to continue a scan. The
seqscan interface allows entry deletion while a scan is in progress using
dshash_delete_current().
Reviewed-By: Andres Freund <andres@anarazel.de>
Author: Kyotaro Horiguchi <horikyoga.ntt@gmail.com>
Borrow the logic that's long been used in tuplesort.c: instead
of physically swapping the data in two heap entries, keep the
value that's being sifted up or down in a local variable, and
just move the other values as necessary. This makes the code
shorter as well as faster. It's not clear that any current
callers are really time-critical enough to notice, but we
might as well code heap maintenance the same way everywhere.
Ma Liangzhu and Tom Lane
Discussion: https://postgr.es/m/17336-fc4e522d26a750fd@postgresql.org
Standardize on xoroshiro128** as our basic PRNG algorithm, eliminating
a bunch of platform dependencies as well as fundamentally-obsolete PRNG
code. In addition, this API replacement will ease replacing the
algorithm again in future, should that become necessary.
xoroshiro128** is a few percent slower than the drand48 family,
but it can produce full-width 64-bit random values not only 48-bit,
and it should be much more trustworthy. It's likely to be noticeably
faster than the platform's random(), depending on which platform you
are thinking about; and we can have non-global state vectors easily,
unlike with random(). It is not cryptographically strong, but neither
are the functions it replaces.
Fabien Coelho, reviewed by Dean Rasheed, Aleksander Alekseev, and myself
Discussion: https://postgr.es/m/alpine.DEB.2.22.394.2105241211230.165418@pseudo
This also involves renaming src/include/utils/hashutils.h, which
becomes src/include/common/hashfn.h. Perhaps an argument can be
made for keeping the hashutils.h name, but it seemed more
consistent to make it match the name of the file, and also more
descriptive of what is actually going on here.
Patch by me, reviewed by Suraj Kharage and Mark Dilger. Off-list
advice on how not to break the Windows build from Davinder Singh
and Amit Kapila.
Discussion: http://postgr.es/m/CA+TgmoaRiG4TXND8QuM6JXFRkM_1wL2ZNhzaUKsuec9-4yrkgw@mail.gmail.com
There's plenty places in frontend code that could benefit from a
string buffer implementation. Some because it yields simpler and
faster code, and some others because of the desire to share code
between backend and frontend.
While there is a string buffer implementation available to frontend
code, libpq's PQExpBuffer, it is clunkier than stringinfo, it
introduces a libpq dependency, doesn't allow for sharing between
frontend and backend code, and has a higher API/ABI stability
requirement due to being exposed via libpq.
Therefore it seems best to just making StringInfo being usable by
frontend code. There's not much to do for that, except for rewriting
two subsequent elog/ereport calls into others types of error
reporting, and deciding on a maximum string length.
For the maximum string size I decided to privately define MaxAllocSize
to the same value as used in the backend. It seems likely that we'll
want to reconsider this for both backend and frontend code in the not
too far away future.
For now I've left stringinfo.h in lib/, rather than common/, to reduce
the likelihood of unnecessary breakage. We could alternatively decide
to provide a redirecting stringinfo.h in lib/, or just not provide
compatibility.
Author: Andres Freund
Reviewed-By: Kyotaro Horiguchi, Daniel Gustafsson
Discussion: https://postgr.es/m/20190920051857.2fhnvhvx4qdddviz@alap3.anarazel.de
When maintaining or merging patches, one of the most common sources
for conflicts are the list of objects in makefiles. Especially when
the split across lines has been changed on both sides, which is
somewhat common due to attempting to stay below 80 columns, those
conflicts are unnecessarily laborious to resolve.
By splitting, and alphabetically sorting, OBJS style lines into one
object per line, conflicts should be less frequent, and easier to
resolve when they still occur.
Author: Andres Freund
Discussion: https://postgr.es/m/20191029200901.vww4idgcxv74cwes@alap3.anarazel.de
This addresses a couple of issues in the code:
- Typos and inconsistencies in comments and function declarations.
- Removal of unreferenced function declarations.
- Removal of unnecessary compile flags.
- A cleanup error in regressplans.sh.
Author: Alexander Lakhin
Discussion: https://postgr.es/m/0c991fdf-2670-1997-c027-772a420c4604@gmail.com
There were a number of issues in the recent commits which include typos,
code and comments mismatch, leftover function declarations. Fix them.
Reported-by: Alexander Lakhin
Author: Alexander Lakhin, Amit Kapila and Amit Langote
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/ef0c0232-0c1d-3a35-63d4-0ebd06e31387@gmail.com
Coverity complained that simple8b_encode() might read beyond the end of
the 'diffs' array, in the loop to encode the integers. That was a false
positive, because we never get into the loop in modes 0 or 1, and the
array is large enough for all the other modes. But I admit it's very
subtle, so it's not surprising that Coverity didn't see it, and it's not
very obvious to humans either. Refactor it, so that the second loop
re-computes the differences, instead of carrying them over from the first
loop in the 'diffs' array. This way, the 'diffs' array is not needed
anymore. It makes no measurable difference in performance, and seems more
straightforward this way.
Also, improve the comments in simple8b_encode(): fix the comment about its
return value that was flat-out wrong, and explain the condition when it
returns EMPTY_CODEWORD better.
In the passing, move the 'selector' from the codeword's low bits to the
high bits. It doesn't matter much, but looking at the original paper, and
googling around for other Simple-8b implementations, that's how it's
usually done.
Per Coverity, and Tom Lane's report off-list.
There were more large constants that needed UINT64CONST. And one variable
was declared as "int", when it needed to be uint64. These bugs were only
visible on 32-bit systems; clearly I should've tested on one, given that
this code does a lot of work with 64-bit integers.
Also, in the test "huge distances" test, the code created some values with
random distances between them, but the test logic didn't take into account
the possibility that the random distance was exactly 1. That never actually
happens with the seed we're using, but let's be tidy.
The set is implemented as a B-tree, with a compact representation at leaf
items, using Simple-8b algorithm, so that clusters of nearby values use
less memory.
The IntegerSet isn't used for anything yet, aside from the test code, but
we have two patches in the works that would benefit from this: A patch to
allow GiST vacuum to delete empty pages, and a patch to reduce heap
VACUUM's memory usage, by storing the list of dead TIDs more efficiently
and lifting the 1 GB limit on its size.
This includes a unit test module, in src/test/modules/test_integerset.
It can be used to verify correctness, as a regression test, but if you run
it manully, it can also print memory usage and execution time of some of
the tests.
Author: Heikki Linnakangas, Andrey Borodin
Reviewed-by: Julien Rouhaud
Discussion: https://www.postgresql.org/message-id/b5e82599-1966-5783-733c-1a947ddb729f@iki.fi
... as well as its implementation from backend/access/hash/hashfunc.c to
backend/utils/hash/hashfn.c.
access/hash is the place for the hash index AM, not really appropriate
for generic facilities, which is what hash_any is; having things the old
way meant that anything using hash_any had to include the AM's include
file, pointlessly polluting its namespace with unrelated, unnecessary
cruft.
Also move the HTEqual strategy number to access/stratnum.h from
access/hash.h.
To avoid breaking third-party extension code, add an #include
"utils/hashutils.h" to access/hash.h. (An easily removed line by
committers who enjoy their asbestos suits to protect them from angry
extension authors.)
Discussion: https://postgr.es/m/201901251935.ser5e4h6djt2@alvherre.pgsql
Test for the compiler builtins __builtin_clz, __builtin_ctz, and
__builtin_popcount, and make use of these in preference to
handwritten C code if they're available. Create src/port
infrastructure for "leftmost one", "rightmost one", and "popcount"
so as to centralize these decisions.
On x86_64, __builtin_popcount generally won't make use of the POPCNT
opcode because that's not universally supported yet. Provide code
that checks CPUID and then calls POPCNT via asm() if available.
This requires indirecting through a function pointer, which is
an annoying amount of overhead for a one-instruction operation,
but it's probably not worth working harder than this for our
current use-cases.
I'm not sure we've found all the existing places that could profit
from this new infrastructure; but we at least touched all the
ones that used copied-and-pasted versions of the bitmapset.c code,
and got rid of multiple copies of the associated constant arrays.
While at it, replace c-compiler.m4's one-per-builtin-function
macros with a single one that can handle all the cases we need
to worry about so far. Also, because I'm paranoid, make those
checks into AC_LINK checks rather than just AC_COMPILE; the
former coding failed to verify that libgcc has support for the
builtin, in cases where it's not inline code.
David Rowley, Thomas Munro, Alvaro Herrera, Tom Lane
Discussion: https://postgr.es/m/CAKJS1f9WTAGG1tPeJnD18hiQW5gAk59fQ6WK-vfdAKEHyRg2RA@mail.gmail.com
This reverts commits fc6c72747a, 109de05cbb, d0b4663c23 and
711bab1e4d.
Somebody will have to try harder before submitting this patch again.
I've spent entirely too much time on it already, and the #ifdef maze yet
to be written in order for it to build at all got on my nerves. The
amount of work needed to get a platform-specific performance improvement
that's barely above the noise level is not worth it.
These opcodes have been around in the AMD world since 2007, and 2008 in
the case of intel. They're supported in GCC and Clang via some __builtin
macros. The opcodes may be unavailable during runtime, in which case we
fall back on a C-based implementation of the code. In order to get the
POPCNT instruction we must pass the -mpopcnt option to the compiler. We
do this only for the pg_bitutils.c file.
David Rowley (with fragments taken from a patch by Thomas Munro)
Discussion: https://postgr.es/m/CAKJS1f9WTAGG1tPeJnD18hiQW5gAk59fQ6WK-vfdAKEHyRg2RA@mail.gmail.com
Alexander Korotkov