Commitb06679e

committed

Ensure age() returns a stable value rather than the latest value

1 parent3652d72 commitb06679eCopy full SHA for b06679e

File tree

+26

-5

lines changed

+26

-5

lines changed

Lines changed: 22 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -391,6 +391,28 @@ GetCurrentTransactionIdIfAny(void)`
`391`	`391`	`}`
`392`	`392`
`393`	`393`
	`394`	`+/*`
	`395`	`+ *GetStableLatestTransactionIdIfAny`
	`396`	`+ *`
	`397`	`+ * Get the latest XID once and then return same value for rest of transaction.`
	`398`	`+ * Acts as a useful reference point for maintenance tasks.`
	`399`	`+ */`
	`400`	`+TransactionId`
	`401`	`+GetStableLatestTransactionId(void)`
	`402`	`+{`
	`403`	`+staticLocalTransactionIdlxid=InvalidLocalTransactionId;`
	`404`	`+staticTransactionIdstablexid=InvalidTransactionId;`
	`405`	`+`
	`406`	`+if (lxid!=MyProc->lxid\|\|`
	`407`	`+!TransactionIdIsValid(stablexid))`
	`408`	`+{`
	`409`	`+lxid=MyProc->lxid;`
	`410`	`+stablexid=ReadNewTransactionId();`
	`411`	`+}`
	`412`	`+`
	`413`	`+returnstablexid;`
	`414`	`+}`
	`415`	`+`
`394`	`416`	`/*`
`395`	`417`	`* AssignTransactionId`
`396`	`418`	`*`

Lines changed: 3 additions & 5 deletions

Original file line number	Diff line number	Diff line change
`@@ -19,6 +19,7 @@`
`19`	`19`	`#include"access/transam.h"`
`20`	`20`	`#include"access/xact.h"`
`21`	`21`	`#include"libpq/pqformat.h"`
	`22`	`+#include"storage/proc.h"`
`22`	`23`	`#include"utils/builtins.h"`
`23`	`24`
`24`	`25`	`#definePG_GETARG_TRANSACTIONID(n)DatumGetTransactionId(PG_GETARG_DATUM(n))`
`@@ -87,16 +88,13 @@ xideq(PG_FUNCTION_ARGS)`
`87`	`88`	`}`
`88`	`89`
`89`	`90`	`/*`
`90`		`- *xid_age- compute age of an XID (relative tocurrent xact)`
	`91`	`+ *xid_age- compute age of an XID (relative tolatest stable xid)`
`91`	`92`	`*/`
`92`	`93`	`Datum`
`93`	`94`	`xid_age(PG_FUNCTION_ARGS)`
`94`	`95`	`{`
`95`	`96`	`TransactionIdxid=PG_GETARG_TRANSACTIONID(0);`
`96`		`-TransactionIdnow=GetTopTransactionIdIfAny();`
`97`		`-`
`98`		`-if (!TransactionIdIsValid(now))`
`99`		`-now=ReadNewTransactionId();`
	`97`	`+TransactionIdnow=GetStableLatestTransactionId();`
`100`	`98`
`101`	`99`	`/* Permanent XIDs are always infinitely old */`
`102`	`100`	`if (!TransactionIdIsNormal(xid))`

Lines changed: 1 addition & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -209,6 +209,7 @@ extern TransactionId GetTopTransactionId(void);`
`209`	`209`	`externTransactionIdGetTopTransactionIdIfAny(void);`
`210`	`210`	`externTransactionIdGetCurrentTransactionId(void);`
`211`	`211`	`externTransactionIdGetCurrentTransactionIdIfAny(void);`
	`212`	`+externTransactionIdGetStableLatestTransactionId(void);`
`212`	`213`	`externSubTransactionIdGetCurrentSubTransactionId(void);`
`213`	`214`	`externCommandIdGetCurrentCommandId(boolused);`
`214`	`215`	`externTimestampTzGetCurrentTransactionStartTimestamp(void);`

Comments

(0)