Fix oldest xid adjustment algorithm

knizhnik · kelvich · commit 7a88fe9fc22e · 2017-11-13T00:15:35.000+03:00
diff --git a/multimaster.c b/multimaster.c
@@ -341,14 +341,14 @@ csn_t MtmTransactionSnapshot(TransactionId xid)
 Snapshot MtmGetSnapshot(Snapshot snapshot)
 {
     snapshot = PgGetSnapshotData(snapshot);
-	RecentGlobalDataXmin = RecentGlobalXmin = MtmAdjustOldestXid(RecentGlobalDataXmin);
+	RecentGlobalDataXmin = RecentGlobalXmin = Mtm->oldestXid;//MtmAdjustOldestXid(RecentGlobalDataXmin);
     return snapshot;
 }
 
 
 TransactionId MtmGetOldestXmin(Relation rel, bool ignoreVacuum)
 {
-    TransactionId xmin = PgGetOldestXmin(NULL, ignoreVacuum); /* consider all backends */
+    TransactionId xmin = PgGetOldestXmin(NULL, false); /* consider all backends */
     xmin = MtmAdjustOldestXid(xmin);
     return xmin;
 }
@@ -539,7 +539,8 @@ MtmAdjustOldestXid(TransactionId xid)
 			if (prev != NULL) { 
 				Mtm->transListHead = prev;
 				Mtm->oldestXid = xid = prev->xid;            
-			} else if (TransactionIdPrecedes(Mtm->oldestXid, xid)) { 
+			} else  {
+				Assert(TransactionIdPrecedesOrEqual(Mtm->oldestXid, xid)); 
 				xid = Mtm->oldestXid;
 			}
 		} else { 

Original file line number	Diff line number	Diff line change
`@@ -341,14 +341,14 @@ csn_t MtmTransactionSnapshot(TransactionId xid)`
`341`	`341`	`Snapshot MtmGetSnapshot(Snapshot snapshot)`
`342`	`342`	`{`
`343`	`343`	`snapshot = PgGetSnapshotData(snapshot);`
`344`		`- RecentGlobalDataXmin = RecentGlobalXmin = MtmAdjustOldestXid(RecentGlobalDataXmin);`
	`344`	`+ RecentGlobalDataXmin = RecentGlobalXmin = Mtm->oldestXid;//MtmAdjustOldestXid(RecentGlobalDataXmin);`
`345`	`345`	`return snapshot;`
`346`	`346`	`}`
`347`	`347`
`348`	`348`
`349`	`349`	`TransactionId MtmGetOldestXmin(Relation rel, bool ignoreVacuum)`
`350`	`350`	`{`
`351`		`- TransactionId xmin = PgGetOldestXmin(NULL, ignoreVacuum); /* consider all backends */`
	`351`	`+ TransactionId xmin = PgGetOldestXmin(NULL, false); /* consider all backends */`
`352`	`352`	`xmin = MtmAdjustOldestXid(xmin);`
`353`	`353`	`return xmin;`
`354`	`354`	`}`
`@@ -539,7 +539,8 @@ MtmAdjustOldestXid(TransactionId xid)`
`539`	`539`	`if (prev != NULL) {`
`540`	`540`	`Mtm->transListHead = prev;`
`541`	`541`	`Mtm->oldestXid = xid = prev->xid;`
`542`		`- } else if (TransactionIdPrecedes(Mtm->oldestXid, xid)) {`
	`542`	`+ } else {`
	`543`	`+ Assert(TransactionIdPrecedesOrEqual(Mtm->oldestXid, xid));`
`543`	`544`	`xid = Mtm->oldestXid;`
`544`	`545`	`}`
`545`	`546`	`} else {`