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Fix possible duplicate tuples while GiST scan. Now page is processed

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at once and ItemPointers are collected in memory.

Remove tuple's killing by killtuple() if tuple was moved to another
page - it could produce unaceptable overhead.

Backpatch up to 8.1 because the bug was introduced by GiST's concurrency support.
This commit is contained in:
Teodor Sigaev 2008-08-23 10:43:58 +00:00
parent 7e9308544f
commit 4040629fe1
3 changed files with 113 additions and 90 deletions
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179
src/backend/access/gist/gistget.c
View File

@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.52.2.1 2005/11/22 18:23:03 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.52.2.2 2008/08/23 10:43:58 teodor Exp $
*
*-------------------------------------------------------------------------
*/
@ -30,62 +30,38 @@ static bool gistindex_keytest(IndexTuple tuple, IndexScanDesc scan,
static void
killtuple(Relation r, GISTScanOpaque so, ItemPointer iptr)
{
Buffer buffer = so->curbuf;
Page p;
OffsetNumber offset;
for (;;)
LockBuffer(so->curbuf, GIST_SHARE);
p = (Page) BufferGetPage(so->curbuf);
if (XLByteEQ(so->stack->lsn, PageGetLSN(p)))
{
Page p;
BlockNumber blkno;
OffsetNumber offset,
maxoff;
LockBuffer(buffer, GIST_SHARE);
p = (Page) BufferGetPage(buffer);
if (buffer == so->curbuf && XLByteEQ(so->stack->lsn, PageGetLSN(p)))
{
/* page unchanged, so all is simple */
offset = ItemPointerGetOffsetNumber(iptr);
PageGetItemId(p, offset)->lp_flags |= LP_DELETE;
SetBufferCommitInfoNeedsSave(buffer);
LockBuffer(buffer, GIST_UNLOCK);
break;
}
maxoff = PageGetMaxOffsetNumber(p);
/* page unchanged, so all is simple */
offset = ItemPointerGetOffsetNumber(iptr);
PageGetItemId(p, offset)->lp_flags |= LP_DELETE;
SetBufferCommitInfoNeedsSave(so->curbuf);
}
else
{
OffsetNumber maxoff = PageGetMaxOffsetNumber(p);
for (offset = FirstOffsetNumber; offset <= maxoff; offset = OffsetNumberNext(offset))
{
IndexTuple ituple = (IndexTuple) PageGetItem(p, PageGetItemId(p, offset));
IndexTuple ituple = (IndexTuple) PageGetItem(p, PageGetItemId(p, offset));
if (ItemPointerEquals(&(ituple->t_tid), iptr))
{
/* found */
PageGetItemId(p, offset)->lp_flags |= LP_DELETE;
SetBufferCommitInfoNeedsSave(buffer);
LockBuffer(buffer, GIST_UNLOCK);
if (buffer != so->curbuf)
ReleaseBuffer(buffer);
return;
SetBufferCommitInfoNeedsSave(so->curbuf);
break;
}
}
/* follow right link */
/*
* ??? is it good? if tuple dropped by concurrent vacuum, we will read
* all leaf pages...
*/
blkno = GistPageGetOpaque(p)->rightlink;
LockBuffer(buffer, GIST_UNLOCK);
if (buffer != so->curbuf)
ReleaseBuffer(buffer);
if (blkno == InvalidBlockNumber)
/* can't found, dropped by somebody else */
return;
buffer = ReadBuffer(r, blkno);
}
LockBuffer(so->curbuf, GIST_UNLOCK);
}
/*
@ -146,7 +122,6 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, b
GISTSearchStack *stk;
IndexTuple it;
GISTPageOpaque opaque;
bool resetoffset = false;
int ntids = 0;
so = (GISTScanOpaque) scan->opaque;
@ -171,6 +146,42 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, b
return 0;
}
/*
* check stored pointers from last visit
*/
if ( so->nPageData > 0 )
{
while( ntids < maxtids && so->curPageData < so->nPageData )
{
tids[ ntids ] = scan->xs_ctup.t_self = so->pageData[ so->curPageData ];
so->curPageData ++;
ntids++;
}
if ( ntids == maxtids )
return ntids;
/*
* Go to the next page
*/
stk = so->stack->next;
pfree(so->stack);
so->stack = stk;
/* If we're out of stack entries, we're done */
if (so->stack == NULL)
{
ReleaseBuffer(so->curbuf);
so->curbuf = InvalidBuffer;
return ntids;
}
so->curbuf = ReleaseAndReadBuffer(so->curbuf,
scan->indexRelation,
stk->block);
}
for (;;)
{
/* First of all, we need lock buffer */
@ -178,30 +189,25 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, b
LockBuffer(so->curbuf, GIST_SHARE);
p = BufferGetPage(so->curbuf);
opaque = GistPageGetOpaque(p);
resetoffset = false;
if (XLogRecPtrIsInvalid(so->stack->lsn) || !XLByteEQ(so->stack->lsn, PageGetLSN(p)))
{
/* page changed from last visit or visit first time , reset offset */
so->stack->lsn = PageGetLSN(p);
resetoffset = true;
/* remember lsn to identify page changed for tuple's killing */
so->stack->lsn = PageGetLSN(p);
/* check page split, occured from last visit or visit to parent */
if (!XLogRecPtrIsInvalid(so->stack->parentlsn) &&
XLByteLT(so->stack->parentlsn, opaque->nsn) &&
opaque->rightlink != InvalidBlockNumber /* sanity check */ &&
(so->stack->next == NULL || so->stack->next->block != opaque->rightlink) /* check if already
/* check page split, occured from last visit or visit to parent */
if (!XLogRecPtrIsInvalid(so->stack->parentlsn) &&
XLByteLT(so->stack->parentlsn, opaque->nsn) &&
opaque->rightlink != InvalidBlockNumber /* sanity check */ &&
(so->stack->next == NULL || so->stack->next->block != opaque->rightlink) /* check if already
added */ )
{
/* detect page split, follow right link to add pages */
{
/* detect page split, follow right link to add pages */
stk = (GISTSearchStack *) palloc(sizeof(GISTSearchStack));
stk->next = so->stack->next;
stk->block = opaque->rightlink;
stk->parentlsn = so->stack->parentlsn;
memset(&(stk->lsn), 0, sizeof(GistNSN));
so->stack->next = stk;
}
stk = (GISTSearchStack *) palloc(sizeof(GISTSearchStack));
stk->next = so->stack->next;
stk->block = opaque->rightlink;
stk->parentlsn = so->stack->parentlsn;
memset(&(stk->lsn), 0, sizeof(GistNSN));
so->stack->next = stk;
}
/* if page is empty, then just skip it */
@ -224,24 +230,13 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, b
continue;
}
if (!GistPageIsLeaf(p) || resetoffset || ItemPointerIsValid(&scan->currentItemData) == false)
{
if (ScanDirectionIsBackward(dir))
n = PageGetMaxOffsetNumber(p);
else
n = FirstOffsetNumber;
}
if (ScanDirectionIsBackward(dir))
n = PageGetMaxOffsetNumber(p);
else
{
n = ItemPointerGetOffsetNumber(&(scan->currentItemData));
if (ScanDirectionIsBackward(dir))
n = OffsetNumberPrev(n);
else
n = OffsetNumberNext(n);
}
n = FirstOffsetNumber;
/* wonderfull, we can look at page */
so->nPageData = so->curPageData = 0;
for (;;)
{
@ -249,6 +244,20 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, b
if (!OffsetNumberIsValid(n))
{
while( ntids < maxtids && so->curPageData < so->nPageData )
{
tids[ ntids ] = scan->xs_ctup.t_self = so->pageData[ so->curPageData ];
so->curPageData ++;
ntids++;
}
if ( ntids == maxtids )
{
LockBuffer(so->curbuf, GIST_UNLOCK);
return ntids;
}
/*
* We ran out of matching index entries on the current page,
* so pop the top stack entry and use it to continue the
@ -288,14 +297,8 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, b
if (!(ignore_killed_tuples && ItemIdDeleted(PageGetItemId(p, n))))
{
it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
tids[ntids] = scan->xs_ctup.t_self = it->t_tid;
ntids++;
if (ntids == maxtids)
{
LockBuffer(so->curbuf, GIST_UNLOCK);
return ntids;
}
so->pageData[ so->nPageData ] = it->t_tid;
so->nPageData ++;
}
}
else

15
src/backend/access/gist/gistscan.c
View File

@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.61 2005/09/22 20:44:36 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.61.2.1 2008/08/23 10:43:58 teodor Exp $
*
*-------------------------------------------------------------------------
*/
@ -98,6 +98,7 @@ gistrescan(PG_FUNCTION_ARGS)
ReleaseBuffer(so->markbuf);
so->markbuf = InvalidBuffer;
}
}
else
{
@ -113,6 +114,8 @@ gistrescan(PG_FUNCTION_ARGS)
scan->opaque = so;
}
so->nPageData = so->curPageData = 0;
/* Update scan key, if a new one is given */
if (key && scan->numberOfKeys > 0)
{
@ -179,6 +182,11 @@ gistmarkpos(PG_FUNCTION_ARGS)
so->markbuf = so->curbuf;
}
so->markNPageData = so->nPageData;
so->markCurPageData = so->curPageData;
if ( so->markNPageData > 0 )
memcpy( so->markPageData, so->pageData, sizeof(ItemPointerData) * so->markNPageData );
PG_RETURN_VOID();
}
@ -228,6 +236,11 @@ gistrestrpos(PG_FUNCTION_ARGS)
so->curbuf = so->markbuf;
}
so->nPageData = so->markNPageData;
so->curPageData = so->markNPageData;
if ( so->markNPageData > 0 )
memcpy( so->pageData, so->markPageData, sizeof(ItemPointerData) * so->markNPageData );
PG_RETURN_VOID();
}

9
src/include/access/gist_private.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.8 2005/10/15 02:49:42 momjian Exp $
* $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.8.2.1 2008/08/23 10:43:58 teodor Exp $
*
*-------------------------------------------------------------------------
*/
@ -73,6 +73,13 @@ typedef struct GISTScanOpaqueData
MemoryContext tempCxt;
Buffer curbuf;
Buffer markbuf;
ItemPointerData pageData[BLCKSZ/sizeof(IndexTupleData)];
OffsetNumber nPageData;
OffsetNumber curPageData;
ItemPointerData markPageData[BLCKSZ/sizeof(IndexTupleData)];
OffsetNumber markNPageData;
OffsetNumber markCurPageData;
} GISTScanOpaqueData;
typedef GISTScanOpaqueData *GISTScanOpaque;