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Handle heap rewrites even better in logical decoding

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Logical decoding should not publish anything about tables created as
part of a heap rewrite during DDL.  Those tables don't exist externally,
so consumers of logical decoding cannot do anything sensible with that
information.  In ab28feae2b, we worked
around this for built-in logical replication, but that was hack.

This is a more proper fix: We mark such transient heaps using the new
field pg_class.relwrite, linking to the original relation OID.  By
default, we ignore them in logical decoding before they get to the
output plugin.  Optionally, a plugin can register their interest in
getting such changes, if they handle DDL specially, in which case the
new field will help them get information about the actual table.

Reviewed-by: Craig Ringer <craig@2ndquadrant.com>
This commit is contained in:
Peter Eisentraut
2018-03-21 09:13:24 -04:00
parent be8a7a6866
commit 325f2ec555
20 changed files with 113 additions and 103 deletions
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5
contrib/test_decoding/sql/ddl.sql
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@ -67,7 +67,7 @@ INSERT INTO replication_example(somedata, somenum) VALUES (4, 1);
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
ALTER TABLE replication_example ALTER COLUMN somenum TYPE int4 USING (somenum::int4);
-- throw away changes, they contain oids
-- check that this doesn't produce any changes from the heap rewrite
SELECT count(data) FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
INSERT INTO replication_example(somedata, somenum) VALUES (5, 1);
@ -93,12 +93,11 @@ COMMIT;
/* display results */
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
-- hide changes bc of oid visible in full table rewrites
CREATE TABLE tr_unique(id2 serial unique NOT NULL, data int);
INSERT INTO tr_unique(data) VALUES(10);
ALTER TABLE tr_unique RENAME TO tr_pkey;
ALTER TABLE tr_pkey ADD COLUMN id serial primary key;
SELECT count(data) FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1', 'include-rewrites', '1');
INSERT INTO tr_pkey(data) VALUES(1);
--show deletion with primary key