From 741f9d741e6dd9bc9174e4f522fc65b87b8d5ee3 Mon Sep 17 00:00:00 2001 From: Masahiko Sawada Date: Fri, 11 Sep 2026 10:20:46 -0700 Subject: [PATCH] Fix heap_update() ignoring TABLE_UPDATE_NO_LOGICAL for TOAST tuples. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Previously, heap_update() honored TABLE_UPDATE_NO_LOGICAL for the main tuple but passed a hardcoded 0 to the tuple toaster, so the tuples it wrote to the TOAST relation were logged for decoding anyway. That was harmless until commit 28d534e2ae0a gave updates the flag; the insert path has propagated its own ever since suppression was introduced for heap rewrites. REPACK (CONCURRENTLY), the only user of the flag, relies on it to keep the changes it applies to the transient heap out of the logical stream. Logical decoding therefore reassembled the TOAST value and then dereferenced a new tuple that the suppressed record doesn't carry, crashing the backend. This is reachable only if an output plugin asks for the changes made by heap rewrites. In core that is just test_decoding with include-rewrites. Fix this by passing HEAP_INSERT_NO_LOGICAL down to the tuple toaster when TABLE_UPDATE_NO_LOGICAL is set. Backpatch to v19, where REPACK (CONCURRENTLY) was introduced. Reported-by: Thom Brown Author: Antonin Houska Reviewed-by: Masahiko Sawada Reviewed-by: Zhijie Hou (Fujitsu) Reviewed-by: Álvaro Herrera Discussion: https://postgr.es/m/CAA-aLv7L_-dOuHXjLh0Di66dExdOb=uTOzR=jtrqCmV0Wxyd2Q@mail.gmail.com Backpatch-through: 19 --- src/backend/access/heap/heapam.c | 8 ++- src/test/modules/injection_points/Makefile | 3 + .../expected/repack_decode.out | 36 +++++++++++ src/test/modules/injection_points/meson.build | 1 + .../injection_points/specs/repack_decode.spec | 60 +++++++++++++++++++ 5 files changed, 106 insertions(+), 2 deletions(-) create mode 100644 src/test/modules/injection_points/expected/repack_decode.out create mode 100644 src/test/modules/injection_points/specs/repack_decode.spec diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 3514028f427..abba5dfd0e7 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -3961,8 +3961,12 @@ l2: */ if (need_toast) { - /* Note we always use WAL and FSM during updates */ - heaptup = heap_toast_insert_or_update(relation, newtup, &oldtup, 0); + /* + * If logical decoding is not needed, suppress it for the TOAST + * tuples too. We never skip the FSM here. + */ + heaptup = heap_toast_insert_or_update(relation, newtup, &oldtup, + walLogical ? 0 : HEAP_INSERT_NO_LOGICAL); newtupsize = MAXALIGN(heaptup->t_len); } else diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile index a03dae5771c..408a35c3c21 100644 --- a/src/test/modules/injection_points/Makefile +++ b/src/test/modules/injection_points/Makefile @@ -9,6 +9,8 @@ EXTENSION = injection_points DATA = injection_points--1.0.sql PGFILEDESC = "injection_points - facility for injection points" +EXTRA_INSTALL = contrib/test_decoding + REGRESS = injection_points hashagg reindex_conc vacuum REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress @@ -16,6 +18,7 @@ ISOLATION = basic \ inplace \ reindex_concurrently_deferred \ repack \ + repack_decode \ repack_temporal \ repack_temporal_multirange \ repack_toast \ diff --git a/src/test/modules/injection_points/expected/repack_decode.out b/src/test/modules/injection_points/expected/repack_decode.out new file mode 100644 index 00000000000..0de24241bfb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_decode.out @@ -0,0 +1,36 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_wait_before_lock s2_changes s2_wakeup_before_lock s1_decode +injection_points_attach +----------------------- + +(1 row) + +step s1_wait_before_lock: + REPACK (CONCURRENTLY) repack_toast; + +step s2_changes: + UPDATE repack_toast SET t = gen_external() WHERE i=1; + +step s2_wakeup_before_lock: + SELECT injection_points_wakeup('repack-concurrently-before-lock'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s1_wait_before_lock: <... completed> +step s1_decode: + SELECT count(*) FROM pg_logical_slot_peek_changes('s', NULL, NULL, 'include-rewrites', '1'); + +count +----- + 9 +(1 row) + +pg_drop_replication_slot +------------------------ + +(1 row) + diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build index 3365a28d11c..a7b40e084f6 100644 --- a/src/test/modules/injection_points/meson.build +++ b/src/test/modules/injection_points/meson.build @@ -47,6 +47,7 @@ tests += { 'inplace', 'reindex_concurrently_deferred', 'repack', + 'repack_decode', 'repack_temporal', 'repack_temporal_multirange', 'repack_toast', diff --git a/src/test/modules/injection_points/specs/repack_decode.spec b/src/test/modules/injection_points/specs/repack_decode.spec new file mode 100644 index 00000000000..89b4cbcc77e --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_decode.spec @@ -0,0 +1,60 @@ +setup +{ + CREATE EXTENSION injection_points; + + BEGIN; + -- Generate a string of random characters that is not likely to be + -- compressed, but is big enough to be stored externally. + CREATE FUNCTION gen_external() + RETURNS text + LANGUAGE sql as $$ + SELECT string_agg(chr(65 + trunc(25 * random())::int), '') + FROM generate_series(1, 2048) s(x); + $$; + COMMIT; + + SELECT pg_create_logical_replication_slot('s', 'test_decoding'); + + CREATE TABLE repack_toast(i int PRIMARY KEY, t text); + INSERT INTO repack_toast(i, t) VALUES (1, gen_external()); +} + +teardown +{ + DROP TABLE repack_toast; + DROP EXTENSION injection_points; + DROP FUNCTION gen_external(); + SELECT pg_drop_replication_slot('s'); +} + +session s1 +setup +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('repack-concurrently-before-lock', 'wait'); +} +# Perform the initial load and wait for s2 to do some data changes. +step s1_wait_before_lock +{ + REPACK (CONCURRENTLY) repack_toast; +} +step s1_decode +{ + SELECT count(*) FROM pg_logical_slot_peek_changes('s', NULL, NULL, 'include-rewrites', '1'); +} + +session s2 +step s2_changes +{ + UPDATE repack_toast SET t = gen_external() WHERE i=1; +} +step s2_wakeup_before_lock +{ + SELECT injection_points_wakeup('repack-concurrently-before-lock'); +} + +permutation + s1_wait_before_lock + s2_changes + s2_wakeup_before_lock + s1_decode