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When reindexing individual indexes on pg_class it was possible to
either trigger an assertion failure:
TRAP: FailedAssertion("!(!ReindexIsProcessingIndex(((index)->rd_id)))
That's because reindex_index() called SetReindexProcessing() - which
enables an asserts ensuring no index insertions happen into the index
- before calling RelationSetNewRelfilenode(). That not correct for
indexes on pg_class, because RelationSetNewRelfilenode() updates the
relevant pg_class row, which needs to update the indexes.
The are two reasons this wasn't noticed earlier. Firstly the bug
doesn't trigger when reindexing all of pg_class, as reindex_relation
has code "hiding" all yet-to-be-reindexed indexes. Secondly, the bug
only triggers when the the update to pg_class doesn't turn out to be a
HOT update - otherwise there's no index insertion to trigger the
bug. Most of the time there's enough space, making this bug hard to
trigger.
To fix, move RelationSetNewRelfilenode() to before the
SetReindexProcessing() (and, together with some other code, to outside
of the PG_TRY()).
To make sure the error checking intended by SetReindexProcessing() is
more robust, modify CatalogIndexInsert() to check
ReindexIsProcessingIndex() even when the update is a HOT update.
Also add a few regression tests for REINDEXing of system catalogs.
The last two improvements would have prevented some of the issues
fixed in 5c1560606d
from being introduced in the first place.
Reported-By: Michael Paquier
Diagnosed-By: Tom Lane and Andres Freund
Author: Andres Freund
Reviewed-By: Tom Lane
Discussion: https://postgr.es/m/20190418011430.GA19133@paquier.xyz
Backpatch: 9.4-, the bug is present in all branches
108 lines
4.1 KiB
PL/PgSQL
108 lines
4.1 KiB
PL/PgSQL
-- predictability
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SET synchronous_commit = on;
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DROP TABLE IF EXISTS replication_example;
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-- Ensure there's tables with toast datums. To do so, we dynamically
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-- create a function returning a large textblob. We want tables of
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-- different kinds: mapped catalog table, unmapped catalog table,
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-- shared catalog table and usertable.
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CREATE FUNCTION exec(text) returns void language plpgsql volatile
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AS $f$
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BEGIN
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EXECUTE $1;
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END;
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$f$;
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CREATE ROLE justforcomments NOLOGIN;
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SELECT exec(
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format($outer$CREATE FUNCTION iamalongfunction() RETURNS TEXT IMMUTABLE LANGUAGE SQL AS $f$SELECT text %L$f$$outer$,
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(SELECT repeat(string_agg(to_char(g.i, 'FM0000'), ''), 50) FROM generate_series(1, 500) g(i))));
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SELECT exec(
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format($outer$COMMENT ON FUNCTION iamalongfunction() IS %L$outer$,
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iamalongfunction()));
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SELECT exec(
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format($outer$COMMENT ON ROLE JUSTFORCOMMENTS IS %L$outer$,
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iamalongfunction()));
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CREATE TABLE iamalargetable AS SELECT iamalongfunction() longfunctionoutput;
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-- verify toast usage
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SELECT pg_relation_size((SELECT reltoastrelid FROM pg_class WHERE oid = 'pg_proc'::regclass)) > 0;
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SELECT pg_relation_size((SELECT reltoastrelid FROM pg_class WHERE oid = 'pg_description'::regclass)) > 0;
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SELECT pg_relation_size((SELECT reltoastrelid FROM pg_class WHERE oid = 'pg_shdescription'::regclass)) > 0;
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SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
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CREATE TABLE replication_example(id SERIAL PRIMARY KEY, somedata int, text varchar(120));
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INSERT INTO replication_example(somedata) VALUES (1);
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SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
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BEGIN;
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INSERT INTO replication_example(somedata) VALUES (2);
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ALTER TABLE replication_example ADD COLUMN testcolumn1 int;
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INSERT INTO replication_example(somedata, testcolumn1) VALUES (3, 1);
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COMMIT;
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BEGIN;
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INSERT INTO replication_example(somedata) VALUES (3);
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ALTER TABLE replication_example ADD COLUMN testcolumn2 int;
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INSERT INTO replication_example(somedata, testcolumn1, testcolumn2) VALUES (4, 2, 1);
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COMMIT;
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VACUUM FULL pg_am;
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VACUUM FULL pg_amop;
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VACUUM FULL pg_proc;
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VACUUM FULL pg_opclass;
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VACUUM FULL pg_type;
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VACUUM FULL pg_index;
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VACUUM FULL pg_database;
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-- repeated rewrites that fail
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BEGIN;
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CLUSTER pg_class USING pg_class_oid_index;
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CLUSTER pg_class USING pg_class_oid_index;
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ROLLBACK;
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-- repeated rewrites that succeed
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BEGIN;
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CLUSTER pg_class USING pg_class_oid_index;
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CLUSTER pg_class USING pg_class_oid_index;
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CLUSTER pg_class USING pg_class_oid_index;
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COMMIT;
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-- repeated rewrites in different transactions
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VACUUM FULL pg_class;
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VACUUM FULL pg_class;
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-- reindexing of important relations / indexes
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REINDEX TABLE pg_class;
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REINDEX INDEX pg_class_oid_index;
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REINDEX INDEX pg_class_tblspc_relfilenode_index;
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INSERT INTO replication_example(somedata, testcolumn1) VALUES (5, 3);
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BEGIN;
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INSERT INTO replication_example(somedata, testcolumn1) VALUES (6, 4);
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ALTER TABLE replication_example ADD COLUMN testcolumn3 int;
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INSERT INTO replication_example(somedata, testcolumn1, testcolumn3) VALUES (7, 5, 1);
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COMMIT;
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-- make old files go away
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CHECKPOINT;
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SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
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-- trigger repeated rewrites of a system catalog with a toast table,
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-- that previously was buggy: 20180914021046.oi7dm4ra3ot2g2kt@alap3.anarazel.de
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VACUUM FULL pg_proc; VACUUM FULL pg_description; VACUUM FULL pg_shdescription; VACUUM FULL iamalargetable;
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INSERT INTO replication_example(somedata, testcolumn1, testcolumn3) VALUES (8, 6, 1);
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VACUUM FULL pg_proc; VACUUM FULL pg_description; VACUUM FULL pg_shdescription; VACUUM FULL iamalargetable;
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INSERT INTO replication_example(somedata, testcolumn1, testcolumn3) VALUES (9, 7, 1);
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SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
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SELECT pg_drop_replication_slot('regression_slot');
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DROP TABLE IF EXISTS replication_example;
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DROP FUNCTION iamalongfunction();
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DROP FUNCTION exec(text);
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DROP ROLE justforcomments;
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