Tom Lane wrote:
> Bruce Momjian <[EMAIL PROTECTED]> writes:
> > I have been thinking we could improve how quickly VACUUM can expire rows
> > if we update procArray.xmin more frequently for non-SERIALIZABLE
> > transactions.
> > The attached patch updates procArray.xmin in this manner.
>
> This patch is incredibly broken. Didn't you understand what I said
> about how we don't track which snapshots are still alive? You can't
> advance procArray.xmin past the xmin of the oldest live snapshot in the
> backend, and you can't assume that there are no live snapshots at the
> places where this patch assumes that. (Open cursors are one obvious
> counterexample, but I think there are more.)
>
> To make intra-transaction advancing of xmin possible, we'd need to
> explicitly track all of the backend's live snapshots, probably by
> introducing a "snapshot cache" manager that gives out tracked refcounts
> as we do for some other structures like catcache entries. This might
> have some other advantages (I think most of the current CopySnapshot
> operations could be replaced by refcount increments) but it's a whole
> lot more complicated and invasive than what you've got here.
I updated the patch to save the MyProc->xid at the time the first cursor
is created, and not allow the MyProc->xid to be set lower than that
saved value in the current transaction. It added only a few more lines
to the patch.
--
Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Index: src/backend/access/transam/xact.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/access/transam/xact.c,v
retrieving revision 1.238
diff -c -c -r1.238 xact.c
*** src/backend/access/transam/xact.c 22 Mar 2007 19:55:04 -0000 1.238
--- src/backend/access/transam/xact.c 24 Mar 2007 02:18:41 -0000
***************
*** 1563,1569 ****
LWLockRelease(ProcArrayLock);
}
!
PG_TRACE1(transaction__commit, s->transactionId);
/*
--- 1563,1570 ----
LWLockRelease(ProcArrayLock);
}
! set_portal_min_xid(InvalidTransactionId);
!
PG_TRACE1(transaction__commit, s->transactionId);
/*
***************
*** 1802,1807 ****
--- 1803,1810 ----
LWLockRelease(ProcArrayLock);
+ set_portal_min_xid(InvalidTransactionId);
+
/*
* This is all post-transaction cleanup. Note that if an error is raised
* here, it's too late to abort the transaction. This should be just
***************
*** 1969,1974 ****
--- 1972,1979 ----
LWLockRelease(ProcArrayLock);
}
+ set_portal_min_xid(InvalidTransactionId);
+
PG_TRACE1(transaction__abort, s->transactionId);
/*
Index: src/backend/catalog/index.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/catalog/index.c,v
retrieving revision 1.280
diff -c -c -r1.280 index.c
*** src/backend/catalog/index.c 3 Mar 2007 20:08:41 -0000 1.280
--- src/backend/catalog/index.c 24 Mar 2007 02:18:42 -0000
***************
*** 1394,1400 ****
}
else if (indexInfo->ii_Concurrent)
{
! snapshot = CopySnapshot(GetTransactionSnapshot());
OldestXmin = InvalidTransactionId; /* not used */
}
else
--- 1394,1400 ----
}
else if (indexInfo->ii_Concurrent)
{
! snapshot = CopySnapshot(GetTransactionSnapshot(false));
OldestXmin = InvalidTransactionId; /* not used */
}
else
Index: src/backend/commands/cluster.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/commands/cluster.c,v
retrieving revision 1.157
diff -c -c -r1.157 cluster.c
*** src/backend/commands/cluster.c 13 Mar 2007 00:33:39 -0000 1.157
--- src/backend/commands/cluster.c 24 Mar 2007 02:18:42 -0000
***************
*** 204,210 ****
/* Start a new transaction for each relation. */
StartTransactionCommand();
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
cluster_rel(rvtc, true);
CommitTransactionCommand();
}
--- 204,210 ----
/* Start a new transaction for each relation. */
StartTransactionCommand();
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(true));
cluster_rel(rvtc, true);
CommitTransactionCommand();
}
Index: src/backend/commands/indexcmds.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/commands/indexcmds.c,v
retrieving revision 1.157
diff -c -c -r1.157 indexcmds.c
*** src/backend/commands/indexcmds.c 13 Mar 2007 00:33:39 -0000 1.157
--- src/backend/commands/indexcmds.c 24 Mar 2007 02:18:42 -0000
***************
*** 493,499 ****
* We also set ActiveSnapshot to this snap, since functions in indexes may
* need a snapshot.
*/
! snapshot = CopySnapshot(GetTransactionSnapshot());
ActiveSnapshot = snapshot;
/*
--- 493,499 ----
* We also set ActiveSnapshot to this snap, since functions in indexes may
* need a snapshot.
*/
! snapshot = CopySnapshot(GetTransactionSnapshot(false));
ActiveSnapshot = snapshot;
/*
***************
*** 1304,1310 ****
StartTransactionCommand();
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
if (reindex_relation(relid, true))
ereport(NOTICE,
(errmsg("table \"%s\" was reindexed",
--- 1304,1310 ----
StartTransactionCommand();
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(true));
if (reindex_relation(relid, true))
ereport(NOTICE,
(errmsg("table \"%s\" was reindexed",
Index: src/backend/commands/trigger.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/commands/trigger.c,v
retrieving revision 1.214
diff -c -c -r1.214 trigger.c
*** src/backend/commands/trigger.c 19 Mar 2007 23:38:29 -0000 1.214
--- src/backend/commands/trigger.c 24 Mar 2007 02:18:43 -0000
***************
*** 2645,2651 ****
*/
events = &afterTriggers->events;
if (events->head != NULL)
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
/*
* Run all the remaining triggers. Loop until they are all gone, just in
--- 2645,2651 ----
*/
events = &afterTriggers->events;
if (events->head != NULL)
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
/*
* Run all the remaining triggers. Loop until they are all gone, just in
Index: src/backend/commands/vacuum.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/commands/vacuum.c,v
retrieving revision 1.349
diff -c -c -r1.349 vacuum.c
*** src/backend/commands/vacuum.c 14 Mar 2007 18:48:55 -0000 1.349
--- src/backend/commands/vacuum.c 24 Mar 2007 02:18:45 -0000
***************
*** 412,418 ****
{
StartTransactionCommand();
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
}
else
old_context = MemoryContextSwitchTo(anl_context);
--- 412,418 ----
{
StartTransactionCommand();
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
}
else
old_context = MemoryContextSwitchTo(anl_context);
***************
*** 470,476 ****
* necessary if we are called from autovacuum because autovacuum might
* continue on to do an ANALYZE-only call.
*/
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
}
if (vacstmt->vacuum && !IsAutoVacuumWorkerProcess())
--- 470,476 ----
* necessary if we are called from autovacuum because autovacuum might
* continue on to do an ANALYZE-only call.
*/
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
}
if (vacstmt->vacuum && !IsAutoVacuumWorkerProcess())
***************
*** 964,970 ****
if (vacstmt->full)
{
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
}
else
{
--- 964,970 ----
if (vacstmt->full)
{
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
}
else
{
Index: src/backend/executor/functions.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/executor/functions.c,v
retrieving revision 1.112
diff -c -c -r1.112 functions.c
*** src/backend/executor/functions.c 13 Mar 2007 00:33:40 -0000 1.112
--- src/backend/executor/functions.c 24 Mar 2007 02:18:45 -0000
***************
*** 300,306 ****
else
{
CommandCounterIncrement();
! snapshot = CopySnapshot(GetTransactionSnapshot());
}
if (IsA(es->stmt, PlannedStmt))
--- 300,306 ----
else
{
CommandCounterIncrement();
! snapshot = CopySnapshot(GetTransactionSnapshot(false));
}
if (IsA(es->stmt, PlannedStmt))
Index: src/backend/executor/spi.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/executor/spi.c,v
retrieving revision 1.173
diff -c -c -r1.173 spi.c
*** src/backend/executor/spi.c 17 Mar 2007 03:15:38 -0000 1.173
--- src/backend/executor/spi.c 24 Mar 2007 02:18:46 -0000
***************
*** 15,23 ****
--- 15,25 ----
#include "postgres.h"
#include "access/printtup.h"
+ #include "access/transam.h"
#include "catalog/heap.h"
#include "commands/trigger.h"
#include "executor/spi_priv.h"
+ #include "storage/procarray.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/typcache.h"
***************
*** 57,63 ****
static MemoryContext _SPI_procmem(void);
static bool _SPI_checktuples(void);
-
/* =================== interface functions =================== */
int
--- 59,64 ----
***************
*** 997,1004 ****
else
{
CommandCounterIncrement();
! snapshot = GetTransactionSnapshot();
}
/*
* Start portal execution.
--- 998,1006 ----
else
{
CommandCounterIncrement();
! snapshot = GetTransactionSnapshot(false);
}
+ set_portal_min_xid(TransactionXmin);
/*
* Start portal execution.
***************
*** 1530,1536 ****
if (read_only)
ActiveSnapshot = CopySnapshot(saveActiveSnapshot);
else
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
}
else
{
--- 1532,1538 ----
if (read_only)
ActiveSnapshot = CopySnapshot(saveActiveSnapshot);
else
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
}
else
{
Index: src/backend/postmaster/autovacuum.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/postmaster/autovacuum.c,v
retrieving revision 1.34
diff -c -c -r1.34 autovacuum.c
*** src/backend/postmaster/autovacuum.c 13 Mar 2007 00:33:41 -0000 1.34
--- src/backend/postmaster/autovacuum.c 24 Mar 2007 02:18:46 -0000
***************
*** 868,874 ****
StartTransactionCommand();
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
/*
* Clean up any dead statistics collector entries for this DB. We always
--- 868,874 ----
StartTransactionCommand();
/* functions in indexes may want a snapshot set */
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
/*
* Clean up any dead statistics collector entries for this DB. We always
Index: src/backend/storage/ipc/procarray.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/storage/ipc/procarray.c,v
retrieving revision 1.22
diff -c -c -r1.22 procarray.c
*** src/backend/storage/ipc/procarray.c 23 Mar 2007 03:16:39 -0000 1.22
--- src/backend/storage/ipc/procarray.c 24 Mar 2007 02:18:47 -0000
***************
*** 54,60 ****
} ProcArrayStruct;
static ProcArrayStruct *procArray;
!
#ifdef XIDCACHE_DEBUG
--- 54,60 ----
} ProcArrayStruct;
static ProcArrayStruct *procArray;
! static TransactionId portal_min_xid = InvalidTransactionId;
#ifdef XIDCACHE_DEBUG
***************
*** 498,504 ****
*----------
*/
Snapshot
! GetSnapshotData(Snapshot snapshot, bool serializable)
{
ProcArrayStruct *arrayP = procArray;
TransactionId xmin;
--- 498,504 ----
*----------
*/
Snapshot
! GetSnapshotData(Snapshot snapshot, bool set_procArray_xmin)
{
ProcArrayStruct *arrayP = procArray;
TransactionId xmin;
***************
*** 510,519 ****
Assert(snapshot != NULL);
! /* Serializable snapshot must be computed before any other... */
! Assert(serializable ?
! !TransactionIdIsValid(MyProc->xmin) :
! TransactionIdIsValid(MyProc->xmin));
/*
* Allocating space for maxProcs xids is usually overkill; numProcs would
--- 510,517 ----
Assert(snapshot != NULL);
! /* Either we set an xmin, or we already have one. */
! Assert(set_procArray_xmin || TransactionIdIsValid(MyProc->xmin));
/*
* Allocating space for maxProcs xids is usually overkill; numProcs would
***************
*** 656,664 ****
}
}
! if (serializable)
! MyProc->xmin = TransactionXmin = xmin;
!
LWLockRelease(ProcArrayLock);
/*
--- 654,684 ----
}
}
! if (set_procArray_xmin)
! {
! if (xmin != MyProc->xmin)
! fprintf(stderr, "%x:%x: set new xmin old=%x new=%x\n", MyProcPid, MyProc->xid, MyProc->xmin, xmin);
! else
! fprintf(stderr, "%x:%x: not set\n", MyProcPid, MyProc->xid);
! /*
! * ---
! * We need to set MyProc->xmin in a few cases:
! * o set at transaction start for SERIALIZABLE visibility
! * o set for new command in READ COMMITTED mode so
! * VACUUM knows we don't care about completed transactions
! *
! * The problem is that we might have old cursors/portals
! * that need to have old transaction visibility, so we use
! * portal_min_xid to record MyProc->xmin during the first
! * cursors/portals creation, and then don't allow MyProc->xmin
! * to be set lower.
! */
! if (!TransactionIdIsValid(MyProc->xmin) ||
! !TransactionIdIsValid(portal_min_xid) ||
! TransactionIdPrecedesOrEquals(xmin, portal_min_xid))
! MyProc->xmin = TransactionXmin = xmin;
! }
!
LWLockRelease(ProcArrayLock);
/*
***************
*** 987,992 ****
--- 1007,1023 ----
LWLockRelease(ProcArrayLock);
}
+ void set_portal_min_xid(TransactionId xid)
+ {
+ /*
+ * We only want portal_min_xid to be the first
+ * portal's MyProc->xmin, or set to invalid.
+ */
+ if (portal_min_xid == InvalidTransactionId ||
+ xid == InvalidTransactionId)
+ portal_min_xid = xid;
+ }
+
#ifdef XIDCACHE_DEBUG
/*
Index: src/backend/tcop/fastpath.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/tcop/fastpath.c,v
retrieving revision 1.96
diff -c -c -r1.96 fastpath.c
*** src/backend/tcop/fastpath.c 3 Mar 2007 19:32:54 -0000 1.96
--- src/backend/tcop/fastpath.c 24 Mar 2007 02:18:47 -0000
***************
*** 308,314 ****
* Now that we know we are in a valid transaction, set snapshot in case
* needed by function itself or one of the datatype I/O routines.
*/
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
/*
* Begin parsing the buffer contents.
--- 308,314 ----
* Now that we know we are in a valid transaction, set snapshot in case
* needed by function itself or one of the datatype I/O routines.
*/
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
/*
* Begin parsing the buffer contents.
Index: src/backend/tcop/postgres.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/tcop/postgres.c,v
retrieving revision 1.529
diff -c -c -r1.529 postgres.c
*** src/backend/tcop/postgres.c 22 Mar 2007 19:55:04 -0000 1.529
--- src/backend/tcop/postgres.c 24 Mar 2007 02:18:48 -0000
***************
*** 738,744 ****
{
if (needSnapshot)
{
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
needSnapshot = false;
}
stmt = (Node *) pg_plan_query(query, boundParams);
--- 738,744 ----
{
if (needSnapshot)
{
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(true));
needSnapshot = false;
}
stmt = (Node *) pg_plan_query(query, boundParams);
Index: src/backend/tcop/pquery.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/tcop/pquery.c,v
retrieving revision 1.115
diff -c -c -r1.115 pquery.c
*** src/backend/tcop/pquery.c 13 Mar 2007 00:33:42 -0000 1.115
--- src/backend/tcop/pquery.c 24 Mar 2007 02:18:48 -0000
***************
*** 154,160 ****
* Must always set snapshot for plannable queries. Note we assume that
* caller will take care of restoring ActiveSnapshot on exit/error.
*/
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
/*
* Create the QueryDesc object
--- 154,160 ----
* Must always set snapshot for plannable queries. Note we assume that
* caller will take care of restoring ActiveSnapshot on exit/error.
*/
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
/*
* Create the QueryDesc object
***************
*** 489,495 ****
if (snapshot)
ActiveSnapshot = CopySnapshot(snapshot);
else
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
/*
* Create QueryDesc in portal's context; for the moment, set
--- 489,495 ----
if (snapshot)
ActiveSnapshot = CopySnapshot(snapshot);
else
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
/*
* Create QueryDesc in portal's context; for the moment, set
***************
*** 1163,1169 ****
IsA(utilityStmt, NotifyStmt) ||
IsA(utilityStmt, UnlistenStmt) ||
IsA(utilityStmt, CheckPointStmt)))
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
else
ActiveSnapshot = NULL;
--- 1163,1169 ----
IsA(utilityStmt, NotifyStmt) ||
IsA(utilityStmt, UnlistenStmt) ||
IsA(utilityStmt, CheckPointStmt)))
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
else
ActiveSnapshot = NULL;
Index: src/backend/utils/adt/ri_triggers.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/adt/ri_triggers.c,v
retrieving revision 1.92
diff -c -c -r1.92 ri_triggers.c
*** src/backend/utils/adt/ri_triggers.c 15 Mar 2007 23:12:06 -0000 1.92
--- src/backend/utils/adt/ri_triggers.c 24 Mar 2007 02:18:50 -0000
***************
*** 3283,3289 ****
{
CommandCounterIncrement(); /* be sure all my own work is visible */
test_snapshot = CopySnapshot(GetLatestSnapshot());
! crosscheck_snapshot = CopySnapshot(GetTransactionSnapshot());
}
else
{
--- 3283,3289 ----
{
CommandCounterIncrement(); /* be sure all my own work is visible */
test_snapshot = CopySnapshot(GetLatestSnapshot());
! crosscheck_snapshot = CopySnapshot(GetTransactionSnapshot(false));
}
else
{
Index: src/backend/utils/time/tqual.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v
retrieving revision 1.101
diff -c -c -r1.101 tqual.c
*** src/backend/utils/time/tqual.c 5 Jan 2007 22:19:47 -0000 1.101
--- src/backend/utils/time/tqual.c 24 Mar 2007 02:18:50 -0000
***************
*** 1202,1208 ****
* the result with CopySnapshot() if it is to be used very long.
*/
Snapshot
! GetTransactionSnapshot(void)
{
/* First call in transaction? */
if (SerializableSnapshot == NULL)
--- 1202,1208 ----
* the result with CopySnapshot() if it is to be used very long.
*/
Snapshot
! GetTransactionSnapshot(bool set_procArray_xmin)
{
/* First call in transaction? */
if (SerializableSnapshot == NULL)
***************
*** 1214,1220 ****
if (IsXactIsoLevelSerializable)
return SerializableSnapshot;
! LatestSnapshot = GetSnapshotData(&LatestSnapshotData, false);
return LatestSnapshot;
}
--- 1214,1221 ----
if (IsXactIsoLevelSerializable)
return SerializableSnapshot;
! LatestSnapshot = GetSnapshotData(&LatestSnapshotData,
! /* we know we are not Serializable */ set_procArray_xmin);
return LatestSnapshot;
}
Index: src/include/storage/procarray.h
===================================================================
RCS file: /cvsroot/pgsql/src/include/storage/procarray.h,v
retrieving revision 1.12
diff -c -c -r1.12 procarray.h
*** src/include/storage/procarray.h 16 Jan 2007 13:28:57 -0000 1.12
--- src/include/storage/procarray.h 24 Mar 2007 02:18:51 -0000
***************
*** 37,41 ****
--- 37,42 ----
extern void XidCacheRemoveRunningXids(TransactionId xid,
int nxids, TransactionId *xids);
+ extern void set_portal_min_xid(TransactionId xid);
#endif /* PROCARRAY_H */
Index: src/include/utils/tqual.h
===================================================================
RCS file: /cvsroot/pgsql/src/include/utils/tqual.h,v
retrieving revision 1.65
diff -c -c -r1.65 tqual.h
*** src/include/utils/tqual.h 5 Jan 2007 22:19:59 -0000 1.65
--- src/include/utils/tqual.h 24 Mar 2007 02:18:51 -0000
***************
*** 142,154 ****
extern HTSV_Result HeapTupleSatisfiesVacuum(HeapTupleHeader tuple,
TransactionId OldestXmin, Buffer buffer);
! extern Snapshot GetTransactionSnapshot(void);
extern Snapshot GetLatestSnapshot(void);
extern Snapshot CopySnapshot(Snapshot snapshot);
extern void FreeSnapshot(Snapshot snapshot);
extern void FreeXactSnapshot(void);
/* in procarray.c; declared here to avoid including tqual.h in procarray.h: */
! extern Snapshot GetSnapshotData(Snapshot snapshot, bool serializable);
#endif /* TQUAL_H */
--- 142,154 ----
extern HTSV_Result HeapTupleSatisfiesVacuum(HeapTupleHeader tuple,
TransactionId OldestXmin, Buffer buffer);
! extern Snapshot GetTransactionSnapshot(bool set_procArray_xmin);
extern Snapshot GetLatestSnapshot(void);
extern Snapshot CopySnapshot(Snapshot snapshot);
extern void FreeSnapshot(Snapshot snapshot);
extern void FreeXactSnapshot(void);
/* in procarray.c; declared here to avoid including tqual.h in procarray.h: */
! extern Snapshot GetSnapshotData(Snapshot snapshot, bool set_procArray_xmin);
#endif /* TQUAL_H */
Index: src/pl/plpgsql/src/pl_exec.c
===================================================================
RCS file: /cvsroot/pgsql/src/pl/plpgsql/src/pl_exec.c,v
retrieving revision 1.190
diff -c -c -r1.190 pl_exec.c
*** src/pl/plpgsql/src/pl_exec.c 15 Mar 2007 23:12:07 -0000 1.190
--- src/pl/plpgsql/src/pl_exec.c 24 Mar 2007 02:18:53 -0000
***************
*** 4124,4130 ****
if (!estate->readonly_func)
{
CommandCounterIncrement();
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
}
/*
--- 4124,4130 ----
if (!estate->readonly_func)
{
CommandCounterIncrement();
! ActiveSnapshot = CopySnapshot(GetTransactionSnapshot(false));
}
/*
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