diff options
Diffstat (limited to 'src/backend/utils/adt/xid.c')
| -rw-r--r-- | src/backend/utils/adt/xid.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/src/backend/utils/adt/xid.c b/src/backend/utils/adt/xid.c index 2051709fdef..14c4a645523 100644 --- a/src/backend/utils/adt/xid.c +++ b/src/backend/utils/adt/xid.c @@ -147,6 +147,32 @@ xidComparator(const void *arg1, const void *arg2) return 0; } +/* + * xidLogicalComparator + * qsort comparison function for XIDs + * + * This is used to compare only XIDs from the same epoch (e.g. for backends + * running at the same time). So there must be only normal XIDs, so there's + * no issue with triangle inequality. + */ +int +xidLogicalComparator(const void *arg1, const void *arg2) +{ + TransactionId xid1 = *(const TransactionId *) arg1; + TransactionId xid2 = *(const TransactionId *) arg2; + + Assert(TransactionIdIsNormal(xid1)); + Assert(TransactionIdIsNormal(xid2)); + + if (TransactionIdPrecedes(xid1, xid2)) + return -1; + + if (TransactionIdPrecedes(xid2, xid1)) + return 1; + + return 0; +} + /***************************************************************************** * COMMAND IDENTIFIER ROUTINES * *****************************************************************************/ |