From bac2fae05c7737530a6fe8276cd27d210d25c6ac Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Fri, 13 Sep 2019 16:36:28 -0300 Subject: [PATCH] logical decoding: process ASSIGNMENT during snapshot build Most WAL records are ignored in early SnapBuild snapshot build phases. But it's critical to process some of them, so that later messages have the correct transaction state after the snapshot is completely built; in particular, XLOG_XACT_ASSIGNMENT messages are critical in order for sub-transactions to be correctly assigned to their parent transactions, or at least one assert misbehaves, as reported by Ildar Musin. Diagnosed-by: Masahiko Sawada Author: Masahiko Sawada Discussion: https://postgr.es/m/CAONYFtOv+Er1p3WAuwUsy1zsCFrSYvpHLhapC_fMD-zNaRWxYg@mail.gmail.com --- src/backend/replication/logical/decode.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c index 5315d93af0..c53e7e2279 100644 --- a/src/backend/replication/logical/decode.c +++ b/src/backend/replication/logical/decode.c @@ -217,12 +217,15 @@ DecodeXactOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf) uint8 info = XLogRecGetInfo(r) & XLOG_XACT_OPMASK; /* - * No point in doing anything yet, data could not be decoded anyway. It's - * ok not to call ReorderBufferProcessXid() in that case, except in the - * assignment case there'll not be any later records with the same xid; - * and in the assignment case we'll not decode those xacts. + * If the snapshot isn't yet fully built, we cannot decode anything, so + * bail out. + * + * However, it's critical to process XLOG_XACT_ASSIGNMENT records even + * when the snapshot is being built: it is possible to get later records + * that require subxids to be properly assigned. */ - if (SnapBuildCurrentState(builder) < SNAPBUILD_FULL_SNAPSHOT) + if (SnapBuildCurrentState(builder) < SNAPBUILD_FULL_SNAPSHOT && + info != XLOG_XACT_ASSIGNMENT) return; switch (info)