diff options
Diffstat (limited to 'src/backend')
| -rw-r--r-- | src/backend/access/transam/xact.c | 22 | ||||
| -rw-r--r-- | src/backend/utils/adt/xid.c | 8 |
2 files changed, 25 insertions, 5 deletions
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 7f412b10d75..1654a0e5c73 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -392,6 +392,28 @@ GetCurrentTransactionIdIfAny(void) /* + * GetStableLatestTransactionIdIfAny + * + * Get the latest XID once and then return same value for rest of transaction. + * Acts as a useful reference point for maintenance tasks. + */ +TransactionId +GetStableLatestTransactionId(void) +{ + static LocalTransactionId lxid = InvalidLocalTransactionId; + static TransactionId stablexid = InvalidTransactionId; + + if (lxid != MyProc->lxid || + !TransactionIdIsValid(stablexid)) + { + lxid = MyProc->lxid; + stablexid = ReadNewTransactionId(); + } + + return stablexid; +} + +/* * AssignTransactionId * * Assigns a new permanent XID to the given TransactionState. diff --git a/src/backend/utils/adt/xid.c b/src/backend/utils/adt/xid.c index eeda081ad18..da9da8a29b9 100644 --- a/src/backend/utils/adt/xid.c +++ b/src/backend/utils/adt/xid.c @@ -19,6 +19,7 @@ #include "access/transam.h" #include "access/xact.h" #include "libpq/pqformat.h" +#include "storage/proc.h" #include "utils/builtins.h" #define PG_GETARG_TRANSACTIONID(n) DatumGetTransactionId(PG_GETARG_DATUM(n)) @@ -87,16 +88,13 @@ xideq(PG_FUNCTION_ARGS) } /* - * xid_age - compute age of an XID (relative to current xact) + * xid_age - compute age of an XID (relative to latest stable xid) */ Datum xid_age(PG_FUNCTION_ARGS) { TransactionId xid = PG_GETARG_TRANSACTIONID(0); - TransactionId now = GetTopTransactionIdIfAny(); - - if (!TransactionIdIsValid(now)) - now = ReadNewTransactionId(); + TransactionId now = GetStableLatestTransactionId(); /* Permanent XIDs are always infinitely old */ if (!TransactionIdIsNormal(xid)) |