mirror of https://github.com/postgres/postgres
per previous discussion on pghackers. Most of the duplicate code in different AMs' ambuild routines has been moved out to a common routine in index.c; this means that all index types now do the right things about inserting recently-dead tuples, etc. (I also removed support for EXTEND INDEX in the ambuild routines, since that's about to go away anyway, and it cluttered the code a lot.) The retail indextuple deletion routines have been replaced by a "bulk delete" routine in which the indexscan is inside the access method. I haven't pushed this change as far as it should go yet, but it should allow considerable simplification of the internal bookkeeping for deletions. Also, add flag columns to pg_am to eliminate various hardcoded tests on AM OIDs, and remove unused pg_am columns. Fix rtree and gist index types to not attempt to store NULLs; before this, gist usually crashed, while rtree managed not to crash but computed wacko bounding boxes for NULL entries (which might have had something to do with the performance problems we've heard about occasionally). Add AtEOXact routines to hash, rtree, and gist, all of which have static state that needs to be reset after an error. We discovered this need long ago for btree, but missed the other guys. Oh, one more thing: concurrent VACUUM is now the default.REL7_2_STABLE
Tom Lane
25 years ago
parent
997439f59e
commit
c8076f09d2
@ -1,224 +0,0 @@ |
||||
/*-------------------------------------------------------------------------
|
||||
* |
||||
* btscan.c |
||||
* manage scans on btrees. |
||||
* |
||||
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group |
||||
* Portions Copyright (c) 1994, Regents of the University of California |
||||
* |
||||
* |
||||
* IDENTIFICATION |
||||
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/Attic/nbtscan.c,v 1.33 2001/01/24 19:42:48 momjian Exp $ |
||||
* |
||||
* |
||||
* NOTES |
||||
* Because we can be doing an index scan on a relation while we update |
||||
* it, we need to avoid missing data that moves around in the index. |
||||
* Insertions and page splits are no problem because _bt_restscan() |
||||
* can figure out where the current item moved to, but if a deletion |
||||
* happens at or before the current scan position, we'd better do |
||||
* something to stay in sync. |
||||
* |
||||
* The routines in this file handle the problem for deletions issued |
||||
* by the current backend. Currently, that's all we need, since |
||||
* deletions are only done by VACUUM and it gets an exclusive lock. |
||||
* |
||||
* The scheme is to manage a list of active scans in the current backend. |
||||
* Whenever we remove a record from an index, we check the list of active |
||||
* scans to see if any has been affected. A scan is affected only if it |
||||
* is on the same relation, and the same page, as the update. |
||||
* |
||||
*------------------------------------------------------------------------- |
||||
*/ |
||||
|
||||
#include "postgres.h" |
||||
|
||||
#include "access/nbtree.h" |
||||
|
||||
typedef struct BTScanListData |
||||
{ |
||||
IndexScanDesc btsl_scan; |
||||
struct BTScanListData *btsl_next; |
||||
} BTScanListData; |
||||
|
||||
typedef BTScanListData *BTScanList; |
||||
|
||||
static BTScanList BTScans = (BTScanList) NULL; |
||||
|
||||
static void _bt_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno); |
||||
|
||||
/*
|
||||
* AtEOXact_nbtree() --- clean up nbtree subsystem at xact abort or commit. |
||||
* |
||||
* This is here because it needs to touch this module's static var BTScans. |
||||
*/ |
||||
void |
||||
AtEOXact_nbtree(void) |
||||
{ |
||||
|
||||
/*
|
||||
* Note: these actions should only be necessary during xact abort; but |
||||
* they can't hurt during a commit. |
||||
*/ |
||||
|
||||
/*
|
||||
* Reset the active-scans list to empty. We do not need to free the |
||||
* list elements, because they're all palloc()'d, so they'll go away |
||||
* at end of transaction anyway. |
||||
*/ |
||||
BTScans = NULL; |
||||
|
||||
/* If we were building a btree, we ain't anymore. */ |
||||
BuildingBtree = false; |
||||
} |
||||
|
||||
/*
|
||||
* _bt_regscan() -- register a new scan. |
||||
*/ |
||||
void |
||||
_bt_regscan(IndexScanDesc scan) |
||||
{ |
||||
BTScanList new_el; |
||||
|
||||
new_el = (BTScanList) palloc(sizeof(BTScanListData)); |
||||
new_el->btsl_scan = scan; |
||||
new_el->btsl_next = BTScans; |
||||
BTScans = new_el; |
||||
} |
||||
|
||||
/*
|
||||
* _bt_dropscan() -- drop a scan from the scan list |
||||
*/ |
||||
void |
||||
_bt_dropscan(IndexScanDesc scan) |
||||
{ |
||||
BTScanList chk, |
||||
last; |
||||
|
||||
last = (BTScanList) NULL; |
||||
for (chk = BTScans; |
||||
chk != (BTScanList) NULL && chk->btsl_scan != scan; |
||||
chk = chk->btsl_next) |
||||
last = chk; |
||||
|
||||
if (chk == (BTScanList) NULL) |
||||
elog(ERROR, "btree scan list trashed; can't find 0x%p", (void *) scan); |
||||
|
||||
if (last == (BTScanList) NULL) |
||||
BTScans = chk->btsl_next; |
||||
else |
||||
last->btsl_next = chk->btsl_next; |
||||
|
||||
pfree(chk); |
||||
} |
||||
|
||||
/*
|
||||
* _bt_adjscans() -- adjust all scans in the scan list to compensate |
||||
* for a given deletion |
||||
*/ |
||||
void |
||||
_bt_adjscans(Relation rel, ItemPointer tid) |
||||
{ |
||||
BTScanList l; |
||||
Oid relid; |
||||
|
||||
relid = RelationGetRelid(rel); |
||||
for (l = BTScans; l != (BTScanList) NULL; l = l->btsl_next) |
||||
{ |
||||
if (relid == RelationGetRelid(l->btsl_scan->relation)) |
||||
_bt_scandel(l->btsl_scan, |
||||
ItemPointerGetBlockNumber(tid), |
||||
ItemPointerGetOffsetNumber(tid)); |
||||
} |
||||
} |
||||
|
||||
/*
|
||||
* _bt_scandel() -- adjust a single scan on deletion |
||||
* |
||||
*/ |
||||
static void |
||||
_bt_scandel(IndexScanDesc scan, BlockNumber blkno, OffsetNumber offno) |
||||
{ |
||||
ItemPointer current; |
||||
Buffer buf; |
||||
BTScanOpaque so; |
||||
OffsetNumber start; |
||||
Page page; |
||||
BTPageOpaque opaque; |
||||
|
||||
so = (BTScanOpaque) scan->opaque; |
||||
buf = so->btso_curbuf; |
||||
|
||||
current = &(scan->currentItemData); |
||||
if (ItemPointerIsValid(current) |
||||
&& ItemPointerGetBlockNumber(current) == blkno |
||||
&& ItemPointerGetOffsetNumber(current) >= offno) |
||||
{ |
||||
page = BufferGetPage(buf); |
||||
opaque = (BTPageOpaque) PageGetSpecialPointer(page); |
||||
start = P_FIRSTDATAKEY(opaque); |
||||
if (ItemPointerGetOffsetNumber(current) == start) |
||||
ItemPointerSetInvalid(&(so->curHeapIptr)); |
||||
else |
||||
{ |
||||
|
||||
/*
|
||||
* We have to lock buffer before _bt_step and unlock it after |
||||
* that. |
||||
*/ |
||||
LockBuffer(buf, BT_READ); |
||||
_bt_step(scan, &buf, BackwardScanDirection); |
||||
if (ItemPointerIsValid(current)) |
||||
{ |
||||
Page pg = BufferGetPage(buf); |
||||
BTItem btitem = (BTItem) PageGetItem(pg, |
||||
PageGetItemId(pg, ItemPointerGetOffsetNumber(current))); |
||||
|
||||
so->curHeapIptr = btitem->bti_itup.t_tid; |
||||
LockBuffer(buf, BUFFER_LOCK_UNLOCK); |
||||
} |
||||
} |
||||
} |
||||
|
||||
current = &(scan->currentMarkData); |
||||
if (ItemPointerIsValid(current) |
||||
&& ItemPointerGetBlockNumber(current) == blkno |
||||
&& ItemPointerGetOffsetNumber(current) >= offno) |
||||
{ |
||||
page = BufferGetPage(so->btso_mrkbuf); |
||||
opaque = (BTPageOpaque) PageGetSpecialPointer(page); |
||||
start = P_FIRSTDATAKEY(opaque); |
||||
|
||||
if (ItemPointerGetOffsetNumber(current) == start) |
||||
ItemPointerSetInvalid(&(so->mrkHeapIptr)); |
||||
else |
||||
{ |
||||
ItemPointerData tmp; |
||||
|
||||
tmp = *current; |
||||
*current = scan->currentItemData; |
||||
scan->currentItemData = tmp; |
||||
so->btso_curbuf = so->btso_mrkbuf; |
||||
so->btso_mrkbuf = buf; |
||||
buf = so->btso_curbuf; |
||||
LockBuffer(buf, BT_READ); /* as above */ |
||||
|
||||
_bt_step(scan, &buf, BackwardScanDirection); |
||||
|
||||
so->btso_curbuf = so->btso_mrkbuf; |
||||
so->btso_mrkbuf = buf; |
||||
tmp = *current; |
||||
*current = scan->currentItemData; |
||||
scan->currentItemData = tmp; |
||||
if (ItemPointerIsValid(current)) |
||||
{ |
||||
Page pg = BufferGetPage(buf); |
||||
BTItem btitem = (BTItem) PageGetItem(pg, |
||||
PageGetItemId(pg, ItemPointerGetOffsetNumber(current))); |
||||
|
||||
so->mrkHeapIptr = btitem->bti_itup.t_tid; |
||||
LockBuffer(buf, BUFFER_LOCK_UNLOCK); /* as above */ |
||||
} |
||||
} |
||||
} |
||||
} |
||||
Loading…
Reference in new issue