diff options
Diffstat (limited to 'src/backend/storage/lmgr/predicate.c')
| -rw-r--r-- | src/backend/storage/lmgr/predicate.c | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c index ba93fb199d4..d24919f76b6 100644 --- a/src/backend/storage/lmgr/predicate.c +++ b/src/backend/storage/lmgr/predicate.c @@ -4037,13 +4037,16 @@ CheckForSerializableConflictOutNeeded(Relation relation, Snapshot snapshot) /* * CheckForSerializableConflictOut - * A table AM is reading a tuple that has been modified. After determining - * that it is visible to us, it should call this function with the top - * level xid of the writing transaction. + * A table AM is reading a tuple that has been modified. If it determines + * that the tuple version it is reading is not visible to us, it should + * pass in the top level xid of the transaction that created it. + * Otherwise, if it determines that it is visible to us but it has been + * deleted or there is a newer version available due to an update, it + * should pass in the top level xid of the modifying transaction. * - * This function will check for overlap with our own transaction. If the - * transactions overlap (i.e., they cannot see each other's writes), then we - * have a conflict out. + * This function will check for overlap with our own transaction. If the given + * xid is also serializable and the transactions overlap (i.e., they cannot see + * each other's writes), then we have a conflict out. */ void CheckForSerializableConflictOut(Relation relation, TransactionId xid, Snapshot snapshot) |