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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.
REL8_5_ALPHA1_BRANCH
Teodor Sigaev 17 years ago
parent 42d313f546
commit 1dcf6fdf1b
3 changed files with 128 additions and 91 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 190
      src/backend/access/gist/gistget.c
  2. 14
      src/backend/access/gist/gistscan.c
  3. 15
      src/include/access/gist_private.h

190
src/backend/access/gist/gistget.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.74 2008/06/19 00:46:03 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.75 2008/08/23 10:37:24 teodor Exp $
*
*-------------------------------------------------------------------------
*/
@ -32,63 +32,39 @@ static bool gistindex_keytest(IndexTuple tuple, IndexScanDesc scan,
static void
killtuple(Relation r, GISTScanOpaque so, ItemPointer iptr)
{
Buffer buffer = so->curbuf;
for (;;)
{
Page p;
BlockNumber blkno;
OffsetNumber offset,
maxoff;
LockBuffer(buffer, GIST_SHARE);
gistcheckpage(r, buffer);
p = (Page) BufferGetPage(buffer);
Page p;
OffsetNumber offset;
if (buffer == so->curbuf && XLByteEQ(so->stack->lsn, PageGetLSN(p)))
{
/* page unchanged, so all is simple */
offset = ItemPointerGetOffsetNumber(iptr);
ItemIdMarkDead(PageGetItemId(p, offset));
SetBufferCommitInfoNeedsSave(buffer);
LockBuffer(buffer, GIST_UNLOCK);
break;
}
LockBuffer(so->curbuf, GIST_SHARE);
gistcheckpage(r, so->curbuf);
p = (Page) BufferGetPage(so->curbuf);
maxoff = PageGetMaxOffsetNumber(p);
if (XLByteEQ(so->stack->lsn, PageGetLSN(p)))
{
/* page unchanged, so all is simple */
offset = ItemPointerGetOffsetNumber(iptr);
ItemIdMarkDead(PageGetItemId(p, offset));
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 */
ItemIdMarkDead(PageGetItemId(p, offset));
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);
}
/*
@ -154,7 +130,6 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
GISTSearchStack *stk;
IndexTuple it;
GISTPageOpaque opaque;
bool resetoffset = false;
int64 ntids = 0;
so = (GISTScanOpaque) scan->opaque;
@ -179,6 +154,50 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
return 0;
}
/*
* check stored pointers from last visit
*/
if ( so->nPageData > 0 )
{
/*
* gistgetmulti never should go here
*/
Assert( tbm == NULL );
if ( so->curPageData < so->nPageData )
{
/*
* pageData is already ordered for scan's direction
*/
scan->xs_ctup.t_self = so->pageData[ so->curPageData ].iptr;
scan->xs_recheck = so->pageData[ so->curPageData ].recheck;
so->curPageData ++;
return 1;
}
else
{
/*
* 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 0;
}
so->curbuf = ReleaseAndReadBuffer(so->curbuf,
scan->indexRelation,
stk->block);
}
}
for (;;)
{
CHECK_FOR_INTERRUPTS();
@ -189,30 +208,25 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
gistcheckpage(scan->indexRelation, so->curbuf);
p = BufferGetPage(so->curbuf);
opaque = GistPageGetOpaque(p);
resetoffset = false;
if (XLogRecPtrIsInvalid(so->stack->lsn) || !XLByteEQ(so->stack->lsn, PageGetLSN(p)))
{
/* first visit or page changed from last visit, reset offset */
so->stack->lsn = PageGetLSN(p);
resetoffset = true;
/* 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 */
/* remember lsn to identify page changed for tuple's killing */
so->stack->lsn = PageGetLSN(p);
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;
}
/* check page split, occured since 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 */
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 */
@ -235,25 +249,13 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
continue;
}
if (!GistPageIsLeaf(p) || resetoffset ||
!ItemPointerIsValid(&so->curpos))
{
if (ScanDirectionIsBackward(dir))
n = PageGetMaxOffsetNumber(p);
else
n = FirstOffsetNumber;
}
if (ScanDirectionIsBackward(dir))
n = PageGetMaxOffsetNumber(p);
else
{
n = ItemPointerGetOffsetNumber(&(so->curpos));
if (ScanDirectionIsBackward(dir))
n = OffsetNumberPrev(n);
else
n = OffsetNumberNext(n);
}
n = FirstOffsetNumber;
/* wonderful, we can look at page */
so->nPageData = so->curPageData = 0;
for (;;)
{
@ -261,6 +263,18 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
if (!OffsetNumberIsValid(n))
{
/*
* If we was called from gistgettuple and current buffer contains
* something matched then make a recursive call - it will return
* ItemPointer from so->pageData. But we save buffer pinned to
* support tuple's killing
*/
if ( !tbm && so->nPageData > 0 )
{
LockBuffer(so->curbuf, GIST_UNLOCK);
return gistnext(scan, dir, NULL);
}
/*
* We ran out of matching index entries on the current page,
* so pop the top stack entry and use it to continue the
@ -306,11 +320,9 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
tbm_add_tuples(tbm, &it->t_tid, 1, scan->xs_recheck);
else
{
scan->xs_ctup.t_self = it->t_tid;
/* scan->xs_recheck is already set */
LockBuffer(so->curbuf, GIST_UNLOCK);
return ntids; /* always 1 */
so->pageData[ so->nPageData ].iptr = it->t_tid;
so->pageData[ so->nPageData ].recheck = scan->xs_recheck;
so->nPageData ++;
}
}
}

14
src/backend/access/gist/gistscan.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.70 2008/06/19 00:46:03 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.71 2008/08/23 10:37:24 teodor Exp $
*
*-------------------------------------------------------------------------
*/
@ -63,6 +63,7 @@ gistrescan(PG_FUNCTION_ARGS)
ReleaseBuffer(so->markbuf);
so->markbuf = InvalidBuffer;
}
}
else
{
@ -83,6 +84,7 @@ gistrescan(PG_FUNCTION_ARGS)
*/
ItemPointerSetInvalid(&so->curpos);
ItemPointerSetInvalid(&so->markpos);
so->nPageData = so->curPageData = 0;
/* Update scan key, if a new one is given */
if (key && scan->numberOfKeys > 0)
@ -150,6 +152,11 @@ 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(ItemResult) * so->markNPageData );
PG_RETURN_VOID();
}
@ -199,6 +206,11 @@ 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(ItemResult) * so->markNPageData );
PG_RETURN_VOID();
}

15
src/include/access/gist_private.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.31 2008/06/19 00:46:05 alvherre Exp $
* $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.32 2008/08/23 10:37:24 teodor Exp $
*
*-------------------------------------------------------------------------
*/
@ -58,6 +58,12 @@ typedef struct GISTSTATE
TupleDesc tupdesc;
} GISTSTATE;
typedef struct ItemResult
{
ItemPointerData iptr;
bool recheck;
} ItemResult;
/*
* When we're doing a scan, we need to keep track of the parent stack
* for the marked and current items.
@ -73,6 +79,13 @@ typedef struct GISTScanOpaqueData
ItemPointerData curpos;
Buffer markbuf;
ItemPointerData markpos;
ItemResult pageData[BLCKSZ/sizeof(IndexTupleData)];
OffsetNumber nPageData;
OffsetNumber curPageData;
ItemResult markPageData[BLCKSZ/sizeof(IndexTupleData)];
OffsetNumber markNPageData;
OffsetNumber markCurPageData;
} GISTScanOpaqueData;
typedef GISTScanOpaqueData *GISTScanOpaque;

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