diff options
Diffstat (limited to 'src/backend/utils/time')
| -rw-r--r-- | src/backend/utils/time/snapmgr.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ef9fc15ac36..d07ca1b0b24 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -957,6 +957,36 @@ xmin_cmp(const pairingheap_node *a, const pairingheap_node *b, void *arg) } /* + * Get current RecentGlobalXmin value, as a FullTransactionId. + */ +FullTransactionId +GetFullRecentGlobalXmin(void) +{ + FullTransactionId nextxid_full; + uint32 nextxid_epoch; + TransactionId nextxid_xid; + uint32 epoch; + + Assert(TransactionIdIsNormal(RecentGlobalXmin)); + + /* + * Compute the epoch from the next XID's epoch. This relies on the fact + * that RecentGlobalXmin must be within the 2 billion XID horizon from the + * next XID. + */ + nextxid_full = ReadNextFullTransactionId(); + nextxid_epoch = EpochFromFullTransactionId(nextxid_full); + nextxid_xid = XidFromFullTransactionId(nextxid_full); + + if (RecentGlobalXmin > nextxid_xid) + epoch = nextxid_epoch - 1; + else + epoch = nextxid_epoch; + + return FullTransactionIdFromEpochAndXid(epoch, RecentGlobalXmin); +} + +/* * SnapshotResetXmin * * If there are no more snapshots, we can reset our PGXACT->xmin to InvalidXid. |