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Commitcfe0454

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committed
Use repeatable read isolation level
1 parent8a7dfb1 commitcfe0454

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2 files changed

+40
-24
lines changed

2 files changed

+40
-24
lines changed

‎contrib/pg_xtm/pg_dtm.c‎

Lines changed: 14 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -209,16 +209,20 @@ static void DtmUpdateRecentXmin(void)
209209

210210
staticSnapshotDtmGetSnapshot(Snapshotsnapshot)
211211
{
212-
XTM_TRACE("XTM: DtmGetSnapshot \n");
213-
if (DtmGlobalTransaction/* && !DtmHasSnapshot*/) {
214-
DtmHasSnapshot= true;
215-
DtmEnsureConnection();
216-
DtmGlobalGetSnapshot(DtmConn,DtmNodeId,GetCurrentTransactionId(),&DtmSnapshot);
217-
}
218-
snapshot=GetLocalSnapshotData(snapshot);
219-
if (DtmHasSnapshot) {
220-
DtmCopySnapshot(snapshot,&DtmSnapshot);
221-
DtmUpdateRecentXmin();
212+
if (!IsMVCCSnapshot(snapshot)||snapshot==&CatalogSnapshotData) {
213+
snapshot=GetLocalSnapshotData(snapshot);
214+
}else {
215+
XTM_TRACE("XTM: DtmGetSnapshot \n");
216+
if (DtmGlobalTransaction/* && !DtmHasSnapshot*/) {
217+
DtmHasSnapshot= true;
218+
DtmEnsureConnection();
219+
DtmGlobalGetSnapshot(DtmConn,DtmNodeId,GetCurrentTransactionId(),&DtmSnapshot);
220+
}
221+
snapshot=GetLocalSnapshotData(snapshot);
222+
if (DtmHasSnapshot) {
223+
DtmCopySnapshot(snapshot,&DtmSnapshot);
224+
DtmUpdateRecentXmin();
225+
}
222226
}
223227
returnsnapshot;
224228
}

‎contrib/pg_xtm/tests/transfers.go‎

Lines changed: 26 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@ package main
33
import (
44
"fmt"
55
"sync"
6-
"math/rand"
6+
// "math/rand"
77
"github.com/jackc/pgx"
88
)
99

@@ -94,6 +94,7 @@ func max(a, b int64) int64 {
9494
functransfer(idint,wg*sync.WaitGroup) {
9595
varerrerror
9696
varxids []int32=make([]int32,2)
97+
varnConflicts=0
9798

9899
conn1,err:=pgx.Connect(cfg1)
99100
checkErr(err)
@@ -106,12 +107,12 @@ func transfer(id int, wg *sync.WaitGroup) {
106107
fori:=0;i<N_ITERATIONS;i++ {
107108
//amount := 2*rand.Intn(2) - 1
108109
amount:=1
109-
account1:=rand.Intn(N_ACCOUNTS)
110-
account2:=rand.Intn(N_ACCOUNTS)
110+
account1:=id//rand.Intn(N_ACCOUNTS)
111+
account2:=id//rand.Intn(N_ACCOUNTS)
111112

112113
// strt transaction
113-
exec(conn1,"begin")
114-
exec(conn2,"begin")
114+
exec(conn1,"begin transaction isolation level repeatable read")
115+
exec(conn2,"begin transaction isolation level repeatable read")
115116

116117
// obtain XIDs of paticipants
117118
xids[0]=execQuery(conn1,"select txid_current()")
@@ -121,13 +122,17 @@ func transfer(id int, wg *sync.WaitGroup) {
121122
exec(conn1,"select dtm_begin_transaction($1, $2)",nodes,xids)
122123
exec(conn2,"select dtm_begin_transaction($1, $2)",nodes,xids)
123124

124-
exec(conn1,"update t set v = v + $1 where u=$2",amount,account1)
125-
exec(conn2,"update t set v = v - $1 where u=$2",amount,account2)
126-
127-
commit(conn1,conn2)
125+
if!execUpdate(conn1,"update t set v = v + $1 where u=$2",amount,account1)||
126+
!execUpdate(conn2,"update t set v = v - $1 where u=$2",amount,account2) {
127+
exec(conn1,"rollback")
128+
exec(conn2,"rollback")
129+
nConflicts+=1
130+
i-=1
131+
}else {
132+
commit(conn1,conn2)
133+
}
128134
}
129-
130-
fmt.Println("Test completed")
135+
fmt.Println("Test completed with ",nConflicts," conflicts")
131136
wg.Done()
132137
}
133138

@@ -143,8 +148,8 @@ func inspect(wg *sync.WaitGroup) {
143148
conn2,err:=pgx.Connect(cfg2)
144149
checkErr(err)
145150

146-
exec(conn1,"begin")
147-
exec(conn2,"begin")
151+
exec(conn1,"begin transaction isolation level repeatable read")
152+
exec(conn2,"begin transaction isolation level repeatable read")
148153

149154
// obtain XIDs of paticipants
150155
xids[0]=execQuery(conn1,"select txid_current()")
@@ -192,10 +197,17 @@ func main() {
192197
funcexec(conn*pgx.Conn,stmtstring,arguments...interface{}) {
193198
varerrerror
194199
// fmt.Println(stmt)
195-
_,_=conn.Exec(stmt,arguments... )
200+
_,err=conn.Exec(stmt,arguments... )
196201
checkErr(err)
197202
}
198203

204+
funcexecUpdate(conn*pgx.Conn,stmtstring,arguments...interface{})bool {
205+
varerrerror
206+
// fmt.Println(stmt)
207+
_,err=conn.Exec(stmt,arguments... )
208+
returnerr==nil
209+
}
210+
199211
funcexecQuery(conn*pgx.Conn,stmtstring,arguments...interface{})int32 {
200212
varerrerror
201213
varresultint64

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