pgsql: Fix snapshot handling in logicalmsg_decode - Mailing list pgsql-committers

From Tomas Vondra
Subject pgsql: Fix snapshot handling in logicalmsg_decode
Date
Msg-id E1pUs4o-000A5x-JN@gemulon.postgresql.org
Whole thread Raw
List pgsql-committers
Fix snapshot handling in logicalmsg_decode

Whe decoding a transactional logical message, logicalmsg_decode called
SnapBuildGetOrBuildSnapshot. But we may not have a consistent snapshot
yet at that point. We don't actually need the snapshot in this case
(during replay we'll have the snapshot from the transaction), so in
practice this is harmless. But in assert-enabled build this crashes.

Fixed by requesting the snapshot only in non-transactional case, where
we are guaranteed to have SNAPBUILD_CONSISTENT.

Backpatch to 11. The issue exists since 9.6.

Backpatch-through: 11
Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/84d60912-6eab-9b84-5de3-41765a5449e8@enterprisedb.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/7fe1aa991b622feaabfac5ed9c918fe8a1d598c9

Modified Files
--------------
src/backend/replication/logical/decode.c        | 14 ++++++++++++--
src/backend/replication/logical/reorderbuffer.c | 10 ++++++++++
2 files changed, 22 insertions(+), 2 deletions(-)


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