Xmin calculations should consider only top transaction IDs, and

tglsfdc · tglsfdc · commit 057ea3471f2e · 2004-08-15T17:03:36.000Z
therefore starting with GetCurrentTransactionId is wrong.  Fixes
miscomputation of RecentGlobalXmin leading to bizarre behavior
reported by Gavin Sherry.
diff --git a/src/backend/storage/ipc/sinval.c b/src/backend/storage/ipc/sinval.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.67 2004/08/01 17:32:16 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.68 2004/08/15 17:03:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -673,7 +673,7 @@ GetOldestXmin(bool allDbs)
 	TransactionId result;
 	int			index;
 
-	result = GetCurrentTransactionId();
+	result = GetTopTransactionId();
 
 	LWLockAcquire(SInvalLock, LW_SHARED);
 
@@ -763,7 +763,7 @@ GetSnapshotData(Snapshot snapshot, bool serializable)
 					 errmsg("out of memory")));
 	}
 
-	globalxmin = xmin = GetCurrentTransactionId();
+	globalxmin = xmin = GetTopTransactionId();
 
 	/*
 	 * If we are going to set MyProc->xmin then we'd better get exclusive

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.67 2004/08/01 17:32:16 tgl Exp $`
	`11`	`+ * $PostgreSQL: pgsql/src/backend/storage/ipc/sinval.c,v 1.68 2004/08/15 17:03:36 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -673,7 +673,7 @@ GetOldestXmin(bool allDbs)`
`673`	`673`	`TransactionId result;`
`674`	`674`	`int index;`
`675`	`675`
`676`		`- result = GetCurrentTransactionId();`
	`676`	`+ result = GetTopTransactionId();`
`677`	`677`
`678`	`678`	`LWLockAcquire(SInvalLock, LW_SHARED);`
`679`	`679`
`@@ -763,7 +763,7 @@ GetSnapshotData(Snapshot snapshot, bool serializable)`
`763`	`763`	`errmsg("out of memory")));`
`764`	`764`	`}`
`765`	`765`
`766`		`- globalxmin = xmin = GetCurrentTransactionId();`
	`766`	`+ globalxmin = xmin = GetTopTransactionId();`
`767`	`767`
`768`	`768`	`/*`
`769`	`769`	`* If we are going to set MyProc->xmin then we'd better get exclusive`