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Commit6c6f395

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Since COPY fires triggers, it seems like a good idea for it to use
a frozen (copied) snapshot too. Move execMain's snapshot copying codeout into a subroutine in case we find other places that need it.
1 parent26fcd25 commit6c6f395

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4 files changed

+44
-22
lines changed

4 files changed

+44
-22
lines changed

‎src/backend/commands/copy.c‎

Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.155 2002/05/21 22:05:54 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.156 2002/05/21 22:59:00 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -447,6 +447,7 @@ CopyTo(Relation rel, bool binary, bool oids, FILE *fp,
447447
bool*isvarlena;
448448
int16fld_size;
449449
char*string;
450+
SnapshotmySnapshot;
450451

451452
if (oids&& !rel->rd_rel->relhasoids)
452453
elog(ERROR,"COPY: table %s does not have OIDs",
@@ -494,7 +495,9 @@ CopyTo(Relation rel, bool binary, bool oids, FILE *fp,
494495
CopySendData(&tmp,sizeof(int32),fp);
495496
}
496497

497-
scandesc=heap_beginscan(rel,QuerySnapshot,0,NULL);
498+
mySnapshot=CopyQuerySnapshot();
499+
500+
scandesc=heap_beginscan(rel,mySnapshot,0,NULL);
498501

499502
while ((tuple=heap_getnext(scandesc,ForwardScanDirection))!=NULL)
500503
{

‎src/backend/executor/execMain.c‎

Lines changed: 2 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -27,7 +27,7 @@
2727
*
2828
*
2929
* IDENTIFICATION
30-
* $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.162 2002/05/21 22:05:55 tgl Exp $
30+
* $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.163 2002/05/21 22:59:01 tgl Exp $
3131
*
3232
*-------------------------------------------------------------------------
3333
*/
@@ -101,7 +101,6 @@ TupleDesc
101101
ExecutorStart(QueryDesc*queryDesc,EState*estate)
102102
{
103103
TupleDescresult;
104-
Snapshotes_snapshot;
105104

106105
/* sanity checks */
107106
Assert(queryDesc!=NULL);
@@ -121,22 +120,7 @@ ExecutorStart(QueryDesc *queryDesc, EState *estate)
121120
* for the life of this query, even if it outlives the current command
122121
* and current snapshot.
123122
*/
124-
if (QuerySnapshot==NULL)/* should be set already, but... */
125-
SetQuerySnapshot();
126-
127-
es_snapshot= (Snapshot)palloc(sizeof(SnapshotData));
128-
memcpy(es_snapshot,QuerySnapshot,sizeof(SnapshotData));
129-
if (es_snapshot->xcnt>0)
130-
{
131-
es_snapshot->xip= (TransactionId*)
132-
palloc(es_snapshot->xcnt*sizeof(TransactionId));
133-
memcpy(es_snapshot->xip,QuerySnapshot->xip,
134-
es_snapshot->xcnt*sizeof(TransactionId));
135-
}
136-
else
137-
es_snapshot->xip=NULL;
138-
139-
estate->es_snapshot=es_snapshot;
123+
estate->es_snapshot=CopyQuerySnapshot();
140124

141125
/*
142126
* Initialize the plan

‎src/backend/utils/time/tqual.c‎

Lines changed: 35 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,7 @@
1616
* Portions Copyright (c) 1994, Regents of the University of California
1717
*
1818
* IDENTIFICATION
19-
* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.51 2002/05/21 22:05:55 tgl Exp $
19+
* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.52 2002/05/21 22:59:01 tgl Exp $
2020
*
2121
*-------------------------------------------------------------------------
2222
*/
@@ -963,6 +963,40 @@ SetQuerySnapshot(void)
963963
Assert(QuerySnapshot!=NULL);
964964
}
965965

966+
/*
967+
* CopyQuerySnapshot
968+
*Copy the current query snapshot.
969+
*
970+
* Copying the snapshot is done so that a query is guaranteed to use a
971+
* consistent snapshot for its entire execution life, even if the command
972+
* counter is incremented or SetQuerySnapshot() is called while it runs
973+
* (as could easily happen, due to triggers etc. executing queries).
974+
*
975+
* The copy is palloc'd in the current memory context.
976+
*/
977+
Snapshot
978+
CopyQuerySnapshot(void)
979+
{
980+
Snapshotsnapshot;
981+
982+
if (QuerySnapshot==NULL)/* should be set already, but... */
983+
SetQuerySnapshot();
984+
985+
snapshot= (Snapshot)palloc(sizeof(SnapshotData));
986+
memcpy(snapshot,QuerySnapshot,sizeof(SnapshotData));
987+
if (snapshot->xcnt>0)
988+
{
989+
snapshot->xip= (TransactionId*)
990+
palloc(snapshot->xcnt*sizeof(TransactionId));
991+
memcpy(snapshot->xip,QuerySnapshot->xip,
992+
snapshot->xcnt*sizeof(TransactionId));
993+
}
994+
else
995+
snapshot->xip=NULL;
996+
997+
returnsnapshot;
998+
}
999+
9661000
/*
9671001
* FreeXactSnapshot
9681002
*Free snapshot(s) at end of transaction.

‎src/include/utils/tqual.h‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
99
* Portions Copyright (c) 1994, Regents of the University of California
1010
*
11-
* $Id: tqual.h,v 1.39 2002/05/21 22:05:55 tgl Exp $
11+
* $Id: tqual.h,v 1.40 2002/05/21 22:59:01 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -112,6 +112,7 @@ extern HTSV_Result HeapTupleSatisfiesVacuum(HeapTupleHeader tuple,
112112

113113
externSnapshotGetSnapshotData(boolserializable);
114114
externvoidSetQuerySnapshot(void);
115+
externSnapshotCopyQuerySnapshot(void);
115116
externvoidFreeXactSnapshot(void);
116117

117118
#endif/* TQUAL_H */

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