From ab798a087d99ea8d7d0df4c296fee5787cf5394e Mon Sep 17 00:00:00 2001 From: Arseny Sher Date: Wed, 23 Oct 2019 15:56:46 +0300 Subject: [PATCH 2/2] Stop demanding that top xact must be seen before subxact in decoding. Manifested as ERROR: subtransaction logged without previous top-level txn record , this check forbids legit behaviours like - First xl_xact_assignment record is beyond reading, i.e. earlier restart_lsn. - After restart_lsn there is some change of a subxact. - After that, there is second xl_xact_assignment (for another subxact) revealing relationship between top and first subxact. Such transaction won't be streamed anyway because we hadn't seen it in full; confirmed_flush_lsn must be past all these records. Saying for sure whether xact of some record encountered after snapshot was deserialized can be streamed or not requires to know nextXid (first not yet running xid) as of this snapshot's lsn -- all xids < nextXid possibly hadn't been seen in full and are not subject to decoding. However, generally we don't know nextXid which is taken from xl_running_xacts; in particular snapshot can be serizalized/deserialized at XLOG_END_OF_RECOVERY. Changing that for the sake of the check in question is not worthwhile, so just throw it out instead of trying to relax. --- src/backend/replication/logical/reorderbuffer.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c index 8ce28ad629..6faba6077e 100644 --- a/src/backend/replication/logical/reorderbuffer.c +++ b/src/backend/replication/logical/reorderbuffer.c @@ -778,9 +778,6 @@ ReorderBufferAssignChild(ReorderBuffer *rb, TransactionId xid, txn = ReorderBufferTXNByXid(rb, xid, true, &new_top, lsn, true); subtxn = ReorderBufferTXNByXid(rb, subxid, true, &new_sub, lsn, false); - if (new_top && !new_sub) - elog(ERROR, "subtransaction logged without previous top-level txn record"); - if (!new_sub) { if (subtxn->is_known_as_subxact) -- 2.11.0