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Restore rule for getting global snapshot
1 parent 912aa01 commit 5e1ed84

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3 files changed

+8
-5
lines changed

3 files changed

+8
-5
lines changed

contrib/multimaster/multimaster.c

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -123,6 +123,7 @@ static TransactionId DtmNextXid;
123123
static SnapshotData DtmSnapshot = { HeapTupleSatisfiesMVCC };
124124
static bool DtmHasGlobalSnapshot;
125125
static int DtmLocalXidReserve;
126+
static CommandId DtmCurcid;
126127
static Snapshot DtmLastSnapshot;
127128
static TransactionManager DtmTM = {
128129
DtmGetTransactionStatus,
@@ -630,11 +631,12 @@ static Snapshot DtmGetSnapshot(Snapshot snapshot)
630631
{
631632
if (TransactionIdIsValid(DtmNextXid) && snapshot != &CatalogSnapshotData)
632633
{
633-
if (!DtmHasGlobalSnapshot) {
634+
if (!DtmHasGlobalSnapshot && (snapshot != DtmLastSnapshot || DtmCurcid != GetCurrentCommandId(false))) {
634635
DtmGlobalGetSnapshot(DtmNextXid, &DtmSnapshot, &dtm->minXid);
635636
}
636637
DtmLastSnapshot = snapshot;
637638
DtmMergeWithGlobalSnapshot(snapshot);
639+
DtmCurcid = snapshot->curcid;
638640
if (!IsolationUsesXactSnapshot())
639641
{
640642
/* Use single global snapshot during all transaction for repeatable read isolation level,

contrib/pg_dtm/pg_dtm.c

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -107,6 +107,7 @@ static SnapshotData DtmSnapshot = { HeapTupleSatisfiesMVCC };
107107
static bool DtmHasGlobalSnapshot;
108108
static bool DtmGlobalXidAssigned;
109109
static int DtmLocalXidReserve;
110+
static CommandId DtmCurcid;
110111
static Snapshot DtmLastSnapshot;
111112
static TransactionManager DtmTM = {
112113
DtmGetTransactionStatus,
@@ -600,7 +601,6 @@ DtmGetNewTransactionId(bool isSubXact)
600601
return xid;
601602
}
602603

603-
604604
static Snapshot DtmGetSnapshot(Snapshot snapshot)
605605
{
606606
if (DtmGlobalXidAssigned)
@@ -612,12 +612,13 @@ static Snapshot DtmGetSnapshot(Snapshot snapshot)
612612
return PgGetSnapshotData(snapshot);
613613
}
614614
if (TransactionIdIsValid(DtmNextXid) && snapshot != &CatalogSnapshotData)
615-
{
616-
if (!DtmHasGlobalSnapshot) {
615+
{
616+
if (!DtmHasGlobalSnapshot && (snapshot != DtmLastSnapshot || DtmCurcid != GetCurrentCommandId(false))) {
617617
DtmGlobalGetSnapshot(DtmNextXid, &DtmSnapshot, &dtm->minXid);
618618
}
619619
DtmLastSnapshot = snapshot;
620620
DtmMergeWithGlobalSnapshot(snapshot);
621+
DtmCurcid = snapshot->curcid;
621622
if (!IsolationUsesXactSnapshot())
622623
{
623624
/* Use single global snapshot during all transaction for repeatable read isolation level,

contrib/pg_dtm/tests/dtmbench.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -70,7 +70,7 @@ struct config
7070
nWriters = 10;
7171
nIterations = 1000;
7272
nAccounts = 1000;
73-
isolationLevel = "read committed";
73+
isolationLevel = "repeatable read";//"read committed";
7474
}
7575
};
7676

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