postgres.git / summary / log / commit / refs

commit    96b5033e117141eecf3782ee555f39b3006a732f
Author:   Alvaro Herrera <alvherre@alvh.no-ip.org>
Date:     Fri Sep 13 19:36:28 2019 +0000
First released in: 13.0, 9.4.25, 9.5.20, 9.6.16, 10.11, 11.6, 12.0

    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 151c3ef8825..eef2f886afe 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)


[parent: a0a40f611e9a]