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Fix re-distributing previously distributed invalidation messages during logical decoding.

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Commit 4909b38af0 introduced logic to distribute invalidation messages
from catalog-modifying transactions to all concurrent in-progress
transactions. However, since each transaction distributes not only its
original invalidation messages but also previously distributed
messages to other transactions, this leads to an exponential increase
in allocation request size for invalidation messages, ultimately
causing memory allocation failure.

This commit fixes this issue by tracking distributed invalidation
messages separately per decoded transaction and not redistributing
these messages to other in-progress transactions. The maximum size of
distributed invalidation messages that one transaction can store is
limited to MAX_DISTR_INVAL_MSG_PER_TXN (8MB). Once the size of the
distributed invalidation messages exceeds this threshold, we
invalidate all caches in locations where distributed invalidation
messages need to be executed.

Back-patch to all supported versions where we introduced the fix by
commit 4909b38af0.

Note that this commit adds two new fields to ReorderBufferTXN to store
the distributed transactions. This change breaks ABI compatibility in
back branches, affecting third-party extensions that depend on the
size of the ReorderBufferTXN struct, though this scenario seems
unlikely.

Additionally, it adds a new flag to the txn_flags field of
ReorderBufferTXN to indicate distributed invalidation message
overflow. This should not affect existing implementations, as it is
unlikely that third-party extensions use unused bits in the txn_flags
field.

Bug: #18938 #18942
Author: vignesh C <vignesh21@gmail.com>
Reported-by: Duncan Sands <duncan.sands@deepbluecap.com>
Reported-by: John Hutchins <john.hutchins@wicourts.gov>
Reported-by: Laurence Parry <greenreaper@hotmail.com>
Reported-by: Max Madden <maxmmadden@gmail.com>
Reported-by: Braulio Fdo Gonzalez <brauliofg@gmail.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Discussion: https://postgr.es/m/680bdaf6-f7d1-4536-b580-05c2760c67c6@deepbluecap.com
Discussion: https://postgr.es/m/18942-0ab1e5ae156613ad@postgresql.org
Discussion: https://postgr.es/m/18938-57c9a1c463b68ce0@postgresql.org
Discussion: https://postgr.es/m/CAD1FGCT2sYrP_70RTuo56QTizyc+J3wJdtn2gtO3VttQFpdMZg@mail.gmail.com
Discussion: https://postgr.es/m/CANO2=B=2BT1hSYCE=nuuTnVTnjidMg0+-FfnRnqM6kd23qoygg@mail.gmail.com
Backpatch-through: 13
This commit is contained in:
Masahiko Sawada
2025-06-16 17:35:48 -07:00
parent dd3df0b850
commit 1230be12f0
5 changed files with 210 additions and 33 deletions
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23
contrib/test_decoding/expected/invalidation_distribution.out
View File

@ -1,4 +1,4 @@
Parsed test spec with 2 sessions
Parsed test spec with 3 sessions
starting permutation: s1_insert_tbl1 s1_begin s1_insert_tbl1 s2_alter_pub_add_tbl s1_commit s1_insert_tbl1 s2_get_binary_changes
step s1_insert_tbl1: INSERT INTO tbl1 (val1, val2) VALUES (1, 1);
@ -18,3 +18,24 @@ count
stop
(1 row)
starting permutation: s1_begin s1_insert_tbl1 s3_begin s3_insert_tbl1 s2_alter_pub_add_tbl s1_insert_tbl1 s1_commit s3_commit s2_get_binary_changes
step s1_begin: BEGIN;
step s1_insert_tbl1: INSERT INTO tbl1 (val1, val2) VALUES (1, 1);
step s3_begin: BEGIN;
step s3_insert_tbl1: INSERT INTO tbl1 (val1, val2) VALUES (2, 2);
step s2_alter_pub_add_tbl: ALTER PUBLICATION pub ADD TABLE tbl1;
step s1_insert_tbl1: INSERT INTO tbl1 (val1, val2) VALUES (1, 1);
step s1_commit: COMMIT;
step s3_commit: COMMIT;
step s2_get_binary_changes: SELECT count(data) FROM pg_logical_slot_get_binary_changes('isolation_slot', NULL, NULL, 'proto_version', '1', 'publication_names', 'pub') WHERE get_byte(data, 0) = 73;
count
-----
0
(1 row)
?column?
--------
stop
(1 row)

11
contrib/test_decoding/specs/invalidation_distribution.spec
View File

@ -28,5 +28,16 @@ setup { SET synchronous_commit=on; }
step "s2_alter_pub_add_tbl" { ALTER PUBLICATION pub ADD TABLE tbl1; }
step "s2_get_binary_changes" { SELECT count(data) FROM pg_logical_slot_get_binary_changes('isolation_slot', NULL, NULL, 'proto_version', '1', 'publication_names', 'pub') WHERE get_byte(data, 0) = 73; }
session "s3"
setup { SET synchronous_commit=on; }
step "s3_begin" { BEGIN; }
step "s3_insert_tbl1" { INSERT INTO tbl1 (val1, val2) VALUES (2, 2); }
step "s3_commit" { COMMIT; }
# Expect to get one insert change. LOGICAL_REP_MSG_INSERT = 'I'
permutation "s1_insert_tbl1" "s1_begin" "s1_insert_tbl1" "s2_alter_pub_add_tbl" "s1_commit" "s1_insert_tbl1" "s2_get_binary_changes"
# Expect to get no change because both s1's and s3's transactions
# use the snapshot from before adding the table tbl1 to the
# publication by "s2_alter_pub_add_tbl".
permutation "s1_begin" "s1_insert_tbl1" "s3_begin" "s3_insert_tbl1" "s2_alter_pub_add_tbl" "s1_insert_tbl1" "s1_commit" "s3_commit" "s2_get_binary_changes"