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author | Andres Freund <andres@anarazel.de> | 2018-10-10 13:53:03 -0700 |
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committer | Andres Freund <andres@anarazel.de> | 2018-10-10 13:53:03 -0700 |
commit | 0a0c25594243eb5b5d25a1e7716e0ab993b5dab9 (patch) | |
tree | d1253b91f941b879adff744e771c458b4c585802 /contrib | |
parent | fd66ca083d460c2f759f99fb77b1fca7e1f3d682 (diff) | |
download | postgresql-0a0c25594243eb5b5d25a1e7716e0ab993b5dab9.tar.gz |
Fix logical decoding error when system table w/ toast is repeatedly rewritten.
Repeatedly rewriting a mapped catalog table with VACUUM FULL or
CLUSTER could cause logical decoding to fail with:
ERROR, "could not map filenode \"%s\" to relation OID"
To trigger the problem the rewritten catalog had to have live tuples
with toasted columns.
The problem was triggered as during catalog table rewrites the
heap_insert() check that prevents logical decoding information to be
emitted for system catalogs, failed to treat the new heap's toast table
as a system catalog (because the new heap is not recognized as a
catalog table via RelationIsLogicallyLogged()). The relmapper, in
contrast to the normal catalog contents, does not contain historical
information. After a single rewrite of a mapped table the new relation
is known to the relmapper, but if the table is rewritten twice before
logical decoding occurs, the relfilenode cannot be mapped to a
relation anymore. Which then leads us to error out. This only
happens for toast tables, because the main table contents aren't
re-inserted with heap_insert().
The fix is simple, add a new heap_insert() flag that prevents logical
decoding information from being emitted, and accept during decoding
that there might not be tuple data for toast tables.
Unfortunately that does not fix pre-existing logical decoding
errors. Doing so would require not throwing an error when a filenode
cannot be mapped to a relation during decoding, and that seems too
likely to hide bugs. If it's crucial to fix decoding for an existing
slot, temporarily changing the ERROR in ReorderBufferCommit() to a
WARNING appears to be the best fix.
Author: Andres Freund
Discussion: https://postgr.es/m/20180914021046.oi7dm4ra3ot2g2kt@alap3.anarazel.de
Backpatch: 9.4-, where logical decoding was introduced
Diffstat (limited to 'contrib')
-rw-r--r-- | contrib/test_decoding/expected/rewrite.out | 75 | ||||
-rw-r--r-- | contrib/test_decoding/sql/rewrite.sql | 42 |
2 files changed, 116 insertions, 1 deletions
diff --git a/contrib/test_decoding/expected/rewrite.out b/contrib/test_decoding/expected/rewrite.out index 4dcd489543..3bf2afa931 100644 --- a/contrib/test_decoding/expected/rewrite.out +++ b/contrib/test_decoding/expected/rewrite.out @@ -1,6 +1,61 @@ -- predictability SET synchronous_commit = on; DROP TABLE IF EXISTS replication_example; +-- Ensure there's tables with toast datums. To do so, we dynamically +-- create a function returning a large textblob. We want tables of +-- different kinds: mapped catalog table, unmapped catalog table, +-- shared catalog table and usertable. +CREATE FUNCTION exec(text) returns void language plpgsql volatile + AS $f$ + BEGIN + EXECUTE $1; + END; +$f$; +CREATE ROLE justforcomments NOLOGIN; +SELECT exec( + format($outer$CREATE FUNCTION iamalongfunction() RETURNS TEXT IMMUTABLE LANGUAGE SQL AS $f$SELECT text %L$f$$outer$, + (SELECT repeat(string_agg(to_char(g.i, 'FM0000'), ''), 50) FROM generate_series(1, 500) g(i)))); + exec +------ + +(1 row) + +SELECT exec( + format($outer$COMMENT ON FUNCTION iamalongfunction() IS %L$outer$, + iamalongfunction())); + exec +------ + +(1 row) + +SELECT exec( + format($outer$COMMENT ON ROLE JUSTFORCOMMENTS IS %L$outer$, + iamalongfunction())); + exec +------ + +(1 row) + +CREATE TABLE iamalargetable AS SELECT iamalongfunction() longfunctionoutput; +-- verify toast usage +SELECT pg_relation_size((SELECT reltoastrelid FROM pg_class WHERE oid = 'pg_proc'::regclass)) > 0; + ?column? +---------- + t +(1 row) + +SELECT pg_relation_size((SELECT reltoastrelid FROM pg_class WHERE oid = 'pg_description'::regclass)) > 0; + ?column? +---------- + t +(1 row) + +SELECT pg_relation_size((SELECT reltoastrelid FROM pg_class WHERE oid = 'pg_shdescription'::regclass)) > 0; + ?column? +---------- + t +(1 row) + SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding'); ?column? ---------- @@ -76,6 +131,23 @@ SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'inc COMMIT (15 rows) +-- trigger repeated rewrites of a system catalog with a toast table, +-- that previously was buggy: 20180914021046.oi7dm4ra3ot2g2kt@alap3.anarazel.de +VACUUM FULL pg_proc; VACUUM FULL pg_description; VACUUM FULL pg_shdescription; VACUUM FULL iamalargetable; +INSERT INTO replication_example(somedata, testcolumn1, testcolumn3) VALUES (8, 6, 1); +VACUUM FULL pg_proc; VACUUM FULL pg_description; VACUUM FULL pg_shdescription; VACUUM FULL iamalargetable; +INSERT INTO replication_example(somedata, testcolumn1, testcolumn3) VALUES (9, 7, 1); +SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1'); + data +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + BEGIN + table public.replication_example: INSERT: id[integer]:9 somedata[integer]:8 text[character varying]:null testcolumn1[integer]:6 testcolumn2[integer]:null testcolumn3[integer]:1 + COMMIT + BEGIN + table public.replication_example: INSERT: id[integer]:10 somedata[integer]:9 text[character varying]:null testcolumn1[integer]:7 testcolumn2[integer]:null testcolumn3[integer]:1 + COMMIT +(6 rows) + SELECT pg_drop_replication_slot('regression_slot'); pg_drop_replication_slot -------------------------- @@ -83,3 +155,6 @@ SELECT pg_drop_replication_slot('regression_slot'); (1 row) DROP TABLE IF EXISTS replication_example; +DROP FUNCTION iamalongfunction(); +DROP FUNCTION exec(text); +DROP ROLE justforcomments; diff --git a/contrib/test_decoding/sql/rewrite.sql b/contrib/test_decoding/sql/rewrite.sql index 8a7329423d..4271b82bea 100644 --- a/contrib/test_decoding/sql/rewrite.sql +++ b/contrib/test_decoding/sql/rewrite.sql @@ -3,6 +3,35 @@ SET synchronous_commit = on; DROP TABLE IF EXISTS replication_example; +-- Ensure there's tables with toast datums. To do so, we dynamically +-- create a function returning a large textblob. We want tables of +-- different kinds: mapped catalog table, unmapped catalog table, +-- shared catalog table and usertable. +CREATE FUNCTION exec(text) returns void language plpgsql volatile + AS $f$ + BEGIN + EXECUTE $1; + END; +$f$; +CREATE ROLE justforcomments NOLOGIN; + +SELECT exec( + format($outer$CREATE FUNCTION iamalongfunction() RETURNS TEXT IMMUTABLE LANGUAGE SQL AS $f$SELECT text %L$f$$outer$, + (SELECT repeat(string_agg(to_char(g.i, 'FM0000'), ''), 50) FROM generate_series(1, 500) g(i)))); +SELECT exec( + format($outer$COMMENT ON FUNCTION iamalongfunction() IS %L$outer$, + iamalongfunction())); +SELECT exec( + format($outer$COMMENT ON ROLE JUSTFORCOMMENTS IS %L$outer$, + iamalongfunction())); +CREATE TABLE iamalargetable AS SELECT iamalongfunction() longfunctionoutput; + +-- verify toast usage +SELECT pg_relation_size((SELECT reltoastrelid FROM pg_class WHERE oid = 'pg_proc'::regclass)) > 0; +SELECT pg_relation_size((SELECT reltoastrelid FROM pg_class WHERE oid = 'pg_description'::regclass)) > 0; +SELECT pg_relation_size((SELECT reltoastrelid FROM pg_class WHERE oid = 'pg_shdescription'::regclass)) > 0; + + SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding'); CREATE TABLE replication_example(id SERIAL PRIMARY KEY, somedata int, text varchar(120)); INSERT INTO replication_example(somedata) VALUES (1); @@ -57,6 +86,17 @@ COMMIT; CHECKPOINT; SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1'); -SELECT pg_drop_replication_slot('regression_slot'); +-- trigger repeated rewrites of a system catalog with a toast table, +-- that previously was buggy: 20180914021046.oi7dm4ra3ot2g2kt@alap3.anarazel.de +VACUUM FULL pg_proc; VACUUM FULL pg_description; VACUUM FULL pg_shdescription; VACUUM FULL iamalargetable; +INSERT INTO replication_example(somedata, testcolumn1, testcolumn3) VALUES (8, 6, 1); +VACUUM FULL pg_proc; VACUUM FULL pg_description; VACUUM FULL pg_shdescription; VACUUM FULL iamalargetable; +INSERT INTO replication_example(somedata, testcolumn1, testcolumn3) VALUES (9, 7, 1); +SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1'); + +SELECT pg_drop_replication_slot('regression_slot'); DROP TABLE IF EXISTS replication_example; +DROP FUNCTION iamalongfunction(); +DROP FUNCTION exec(text); +DROP ROLE justforcomments; |