diff options
Diffstat (limited to 'src/backend/access/transam/multixact.c')
| -rw-r--r-- | src/backend/access/transam/multixact.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c index ca702eec817..20814702e6d 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -434,11 +434,14 @@ MultiXactIdExpand(MultiXactId multi, TransactionId xid, MultiXactStatus status) * Determine which of the members of the MultiXactId are still of * interest. This is any running transaction, and also any transaction * that grabbed something stronger than just a lock and was committed. (An - * update that aborted is of no interest here.) + * update that aborted is of no interest here; and having more than one + * update Xid in a multixact would cause errors elsewhere.) * - * (Removing dead members is just an optimization, but a useful one. Note - * we have the same race condition here as above: j could be 0 at the end - * of the loop.) + * Removing dead members is not just an optimization: freezing of tuples + * whose Xmax are multis depends on this behavior. + * + * Note we have the same race condition here as above: j could be 0 at the + * end of the loop. */ newMembers = (MultiXactMember *) palloc(sizeof(MultiXactMember) * (nmembers + 1)); @@ -1052,7 +1055,8 @@ GetMultiXactIdMembers(MultiXactId multi, MultiXactMember **members, debug_elog3(DEBUG2, "GetMembers: asked for %u", multi); - Assert(MultiXactIdIsValid(multi)); + if (!MultiXactIdIsValid(multi)) + return -1; /* See if the MultiXactId is in the local cache */ length = mXactCacheGetById(multi, members); |