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Commit1dcf6fd

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Fix possible duplicate tuples while GiST scan. Now page is processed
at once and ItemPointers are collected in memory.Remove tuple's killing by killtuple() if tuple was moved to anotherpage - it could produce unaceptable overhead.Backpatch up to 8.1 because the bug was introduced by GiST's concurrency support.
1 parent42d313f commit1dcf6fd

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3 files changed

+128
-91
lines changed

3 files changed

+128
-91
lines changed

‎src/backend/access/gist/gistget.c‎

Lines changed: 101 additions & 89 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.74 2008/06/19 00:46:03 alvherre Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.75 2008/08/23 10:37:24 teodor Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -32,63 +32,39 @@ static bool gistindex_keytest(IndexTuple tuple, IndexScanDesc scan,
3232
staticvoid
3333
killtuple(Relationr,GISTScanOpaqueso,ItemPointeriptr)
3434
{
35-
Bufferbuffer=so->curbuf;
36-
37-
for (;;)
38-
{
39-
Pagep;
40-
BlockNumberblkno;
41-
OffsetNumberoffset,
42-
maxoff;
43-
44-
LockBuffer(buffer,GIST_SHARE);
45-
gistcheckpage(r,buffer);
46-
p= (Page)BufferGetPage(buffer);
35+
Pagep;
36+
OffsetNumberoffset;
4737

48-
if (buffer==so->curbuf&&XLByteEQ(so->stack->lsn,PageGetLSN(p)))
49-
{
50-
/* page unchanged, so all is simple */
51-
offset=ItemPointerGetOffsetNumber(iptr);
52-
ItemIdMarkDead(PageGetItemId(p,offset));
53-
SetBufferCommitInfoNeedsSave(buffer);
54-
LockBuffer(buffer,GIST_UNLOCK);
55-
break;
56-
}
38+
LockBuffer(so->curbuf,GIST_SHARE);
39+
gistcheckpage(r,so->curbuf);
40+
p= (Page)BufferGetPage(so->curbuf);
5741

58-
maxoff=PageGetMaxOffsetNumber(p);
42+
if (XLByteEQ(so->stack->lsn,PageGetLSN(p)))
43+
{
44+
/* page unchanged, so all is simple */
45+
offset=ItemPointerGetOffsetNumber(iptr);
46+
ItemIdMarkDead(PageGetItemId(p,offset));
47+
SetBufferCommitInfoNeedsSave(so->curbuf);
48+
}
49+
else
50+
{
51+
OffsetNumbermaxoff=PageGetMaxOffsetNumber(p);
5952

6053
for (offset=FirstOffsetNumber;offset <=maxoff;offset=OffsetNumberNext(offset))
6154
{
62-
IndexTupleituple= (IndexTuple)PageGetItem(p,PageGetItemId(p,offset));
55+
IndexTupleituple= (IndexTuple)PageGetItem(p,PageGetItemId(p,offset));
6356

6457
if (ItemPointerEquals(&(ituple->t_tid),iptr))
6558
{
6659
/* found */
6760
ItemIdMarkDead(PageGetItemId(p,offset));
68-
SetBufferCommitInfoNeedsSave(buffer);
69-
LockBuffer(buffer,GIST_UNLOCK);
70-
if (buffer!=so->curbuf)
71-
ReleaseBuffer(buffer);
72-
return;
61+
SetBufferCommitInfoNeedsSave(so->curbuf);
62+
break;
7363
}
7464
}
75-
76-
/* follow right link */
77-
78-
/*
79-
* ??? is it good? if tuple dropped by concurrent vacuum, we will read
80-
* all leaf pages...
81-
*/
82-
blkno=GistPageGetOpaque(p)->rightlink;
83-
LockBuffer(buffer,GIST_UNLOCK);
84-
if (buffer!=so->curbuf)
85-
ReleaseBuffer(buffer);
86-
87-
if (blkno==InvalidBlockNumber)
88-
/* can't found, dropped by somebody else */
89-
return;
90-
buffer=ReadBuffer(r,blkno);
9165
}
66+
67+
LockBuffer(so->curbuf,GIST_UNLOCK);
9268
}
9369

9470
/*
@@ -154,7 +130,6 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
154130
GISTSearchStack*stk;
155131
IndexTupleit;
156132
GISTPageOpaqueopaque;
157-
boolresetoffset= false;
158133
int64ntids=0;
159134

160135
so= (GISTScanOpaque)scan->opaque;
@@ -179,6 +154,50 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
179154
return0;
180155
}
181156

157+
/*
158+
* check stored pointers from last visit
159+
*/
160+
if (so->nPageData>0 )
161+
{
162+
/*
163+
* gistgetmulti never should go here
164+
*/
165+
Assert(tbm==NULL );
166+
167+
if (so->curPageData<so->nPageData )
168+
{
169+
/*
170+
* pageData is already ordered for scan's direction
171+
*/
172+
scan->xs_ctup.t_self=so->pageData[so->curPageData ].iptr;
173+
scan->xs_recheck=so->pageData[so->curPageData ].recheck;
174+
so->curPageData++;
175+
176+
return1;
177+
}
178+
else
179+
{
180+
/*
181+
* Go to the next page
182+
*/
183+
stk=so->stack->next;
184+
pfree(so->stack);
185+
so->stack=stk;
186+
187+
/* If we're out of stack entries, we're done */
188+
if (so->stack==NULL)
189+
{
190+
ReleaseBuffer(so->curbuf);
191+
so->curbuf=InvalidBuffer;
192+
return0;
193+
}
194+
195+
so->curbuf=ReleaseAndReadBuffer(so->curbuf,
196+
scan->indexRelation,
197+
stk->block);
198+
}
199+
}
200+
182201
for (;;)
183202
{
184203
CHECK_FOR_INTERRUPTS();
@@ -189,30 +208,25 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
189208
gistcheckpage(scan->indexRelation,so->curbuf);
190209
p=BufferGetPage(so->curbuf);
191210
opaque=GistPageGetOpaque(p);
192-
resetoffset= false;
193211

194-
if (XLogRecPtrIsInvalid(so->stack->lsn)|| !XLByteEQ(so->stack->lsn,PageGetLSN(p)))
195-
{
196-
/* first visit or page changed from last visit, reset offset */
197-
so->stack->lsn=PageGetLSN(p);
198-
resetoffset= true;
199-
200-
/* check page split, occured from last visit or visit to parent */
201-
if (!XLogRecPtrIsInvalid(so->stack->parentlsn)&&
202-
XLByteLT(so->stack->parentlsn,opaque->nsn)&&
203-
opaque->rightlink!=InvalidBlockNumber/* sanity check */&&
204-
(so->stack->next==NULL||so->stack->next->block!=opaque->rightlink)/* check if already
205-
added */ )
206-
{
207-
/* detect page split, follow right link to add pages */
212+
/* remember lsn to identify page changed for tuple's killing */
213+
so->stack->lsn=PageGetLSN(p);
208214

209-
stk= (GISTSearchStack*)palloc(sizeof(GISTSearchStack));
210-
stk->next=so->stack->next;
211-
stk->block=opaque->rightlink;
212-
stk->parentlsn=so->stack->parentlsn;
213-
memset(&(stk->lsn),0,sizeof(GistNSN));
214-
so->stack->next=stk;
215-
}
215+
/* check page split, occured since visit to parent */
216+
if (!XLogRecPtrIsInvalid(so->stack->parentlsn)&&
217+
XLByteLT(so->stack->parentlsn,opaque->nsn)&&
218+
opaque->rightlink!=InvalidBlockNumber/* sanity check */&&
219+
(so->stack->next==NULL||so->stack->next->block!=opaque->rightlink)/* check if already
220+
added */ )
221+
{
222+
/* detect page split, follow right link to add pages */
223+
224+
stk= (GISTSearchStack*)palloc(sizeof(GISTSearchStack));
225+
stk->next=so->stack->next;
226+
stk->block=opaque->rightlink;
227+
stk->parentlsn=so->stack->parentlsn;
228+
memset(&(stk->lsn),0,sizeof(GistNSN));
229+
so->stack->next=stk;
216230
}
217231

218232
/* if page is empty, then just skip it */
@@ -235,32 +249,32 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
235249
continue;
236250
}
237251

238-
if (!GistPageIsLeaf(p)||resetoffset||
239-
!ItemPointerIsValid(&so->curpos))
240-
{
241-
if (ScanDirectionIsBackward(dir))
242-
n=PageGetMaxOffsetNumber(p);
243-
else
244-
n=FirstOffsetNumber;
245-
}
252+
if (ScanDirectionIsBackward(dir))
253+
n=PageGetMaxOffsetNumber(p);
246254
else
247-
{
248-
n=ItemPointerGetOffsetNumber(&(so->curpos));
249-
250-
if (ScanDirectionIsBackward(dir))
251-
n=OffsetNumberPrev(n);
252-
else
253-
n=OffsetNumberNext(n);
254-
}
255+
n=FirstOffsetNumber;
255256

256257
/* wonderful, we can look at page */
258+
so->nPageData=so->curPageData=0;
257259

258260
for (;;)
259261
{
260262
n=gistfindnext(scan,n,dir);
261263

262264
if (!OffsetNumberIsValid(n))
263265
{
266+
/*
267+
* If we was called from gistgettuple and current buffer contains
268+
* something matched then make a recursive call - it will return
269+
* ItemPointer from so->pageData. But we save buffer pinned to
270+
* support tuple's killing
271+
*/
272+
if ( !tbm&&so->nPageData>0 )
273+
{
274+
LockBuffer(so->curbuf,GIST_UNLOCK);
275+
returngistnext(scan,dir,NULL);
276+
}
277+
264278
/*
265279
* We ran out of matching index entries on the current page,
266280
* so pop the top stack entry and use it to continue the
@@ -306,11 +320,9 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
306320
tbm_add_tuples(tbm,&it->t_tid,1,scan->xs_recheck);
307321
else
308322
{
309-
scan->xs_ctup.t_self=it->t_tid;
310-
/* scan->xs_recheck is already set */
311-
312-
LockBuffer(so->curbuf,GIST_UNLOCK);
313-
returnntids;/* always 1 */
323+
so->pageData[so->nPageData ].iptr=it->t_tid;
324+
so->pageData[so->nPageData ].recheck=scan->xs_recheck;
325+
so->nPageData++;
314326
}
315327
}
316328
}

‎src/backend/access/gist/gistscan.c‎

Lines changed: 13 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.70 2008/06/19 00:46:03 alvherre Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.71 2008/08/23 10:37:24 teodor Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -63,6 +63,7 @@ gistrescan(PG_FUNCTION_ARGS)
6363
ReleaseBuffer(so->markbuf);
6464
so->markbuf=InvalidBuffer;
6565
}
66+
6667
}
6768
else
6869
{
@@ -83,6 +84,7 @@ gistrescan(PG_FUNCTION_ARGS)
8384
*/
8485
ItemPointerSetInvalid(&so->curpos);
8586
ItemPointerSetInvalid(&so->markpos);
87+
so->nPageData=so->curPageData=0;
8688

8789
/* Update scan key, if a new one is given */
8890
if (key&&scan->numberOfKeys>0)
@@ -150,6 +152,11 @@ gistmarkpos(PG_FUNCTION_ARGS)
150152
so->markbuf=so->curbuf;
151153
}
152154

155+
so->markNPageData=so->nPageData;
156+
so->markCurPageData=so->curPageData;
157+
if (so->markNPageData>0 )
158+
memcpy(so->markPageData,so->pageData,sizeof(ItemResult)*so->markNPageData );
159+
153160
PG_RETURN_VOID();
154161
}
155162

@@ -199,6 +206,11 @@ gistrestrpos(PG_FUNCTION_ARGS)
199206
so->curbuf=so->markbuf;
200207
}
201208

209+
so->nPageData=so->markNPageData;
210+
so->curPageData=so->markNPageData;
211+
if (so->markNPageData>0 )
212+
memcpy(so->pageData,so->markPageData,sizeof(ItemResult)*so->markNPageData );
213+
202214
PG_RETURN_VOID();
203215
}
204216

‎src/include/access/gist_private.h‎

Lines changed: 14 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.31 2008/06/19 00:46:05 alvherre Exp $
10+
* $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.32 2008/08/23 10:37:24 teodor Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -58,6 +58,12 @@ typedef struct GISTSTATE
5858
TupleDesctupdesc;
5959
}GISTSTATE;
6060

61+
typedefstructItemResult
62+
{
63+
ItemPointerDataiptr;
64+
boolrecheck;
65+
}ItemResult;
66+
6167
/*
6268
*When we're doing a scan, we need to keep track of the parent stack
6369
*for the marked and current items.
@@ -73,6 +79,13 @@ typedef struct GISTScanOpaqueData
7379
ItemPointerDatacurpos;
7480
Buffermarkbuf;
7581
ItemPointerDatamarkpos;
82+
83+
ItemResultpageData[BLCKSZ/sizeof(IndexTupleData)];
84+
OffsetNumbernPageData;
85+
OffsetNumbercurPageData;
86+
ItemResultmarkPageData[BLCKSZ/sizeof(IndexTupleData)];
87+
OffsetNumbermarkNPageData;
88+
OffsetNumbermarkCurPageData;
7689
}GISTScanOpaqueData;
7790

7891
typedefGISTScanOpaqueData*GISTScanOpaque;

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