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This feature, building on previous commits, allows the write-ahead log stream to be decoded into a series of logical changes; that is, inserts, updates, and deletes and the transactions which contain them. It is capable of handling decoding even across changes to the schema of the effected tables. The output format is controlled by a so-called "output plugin"; an example is included. To make use of this in a real replication system, the output plugin will need to be modified to produce output in the format appropriate to that system, and to perform filtering. Currently, information can be extracted from the logical decoding system only via SQL; future commits will add the ability to stream changes via walsender. Andres Freund, with review and other contributions from many other people, including Álvaro Herrera, Abhijit Menon-Sen, Peter Gheogegan, Kevin Grittner, Robert Haas, Heikki Linnakangas, Fujii Masao, Abhijit Menon-Sen, Michael Paquier, Simon Riggs, Craig Ringer, and Steve Singer.
67 lines
2.1 KiB
Plaintext
67 lines
2.1 KiB
Plaintext
Parsed test spec with 3 sessions
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starting permutation: s0init s0start s1begin s1sharepgclass s2begin s2sharepgclass s0w s0start s2commit s1commit
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step s0init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
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?column?
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init
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step s0start: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', 'false');
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data
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step s1begin: BEGIN;
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step s1sharepgclass: SELECT count(*) > 1 FROM (SELECT * FROM pg_class FOR SHARE) s;
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?column?
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t
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step s2begin: BEGIN;
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step s2sharepgclass: SELECT count(*) > 1 FROM (SELECT * FROM pg_class FOR SHARE) s;
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?column?
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t
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step s0w: INSERT INTO do_write DEFAULT VALUES;
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step s0start: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', 'false');
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data
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BEGIN
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table public.do_write: INSERT: id[integer]:1
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COMMIT
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step s2commit: COMMIT;
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step s1commit: COMMIT;
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?column?
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stop
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starting permutation: s0init s0start s1begin s1keysharepgclass s2begin s2keysharepgclass s0alter s0w s0start s2commit s1commit
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step s0init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding');
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?column?
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init
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step s0start: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', 'false');
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data
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step s1begin: BEGIN;
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step s1keysharepgclass: SELECT count(*) > 1 FROM (SELECT * FROM pg_class FOR KEY SHARE) s;
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?column?
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t
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step s2begin: BEGIN;
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step s2keysharepgclass: SELECT count(*) > 1 FROM (SELECT * FROM pg_class FOR KEY SHARE) s;
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?column?
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t
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step s0alter: ALTER TABLE do_write ADD column ts timestamptz;
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step s0w: INSERT INTO do_write DEFAULT VALUES;
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step s0start: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', 'false');
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data
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BEGIN
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COMMIT
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BEGIN
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table public.do_write: INSERT: id[integer]:1 ts[timestamp with time zone]:null
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COMMIT
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step s2commit: COMMIT;
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step s1commit: COMMIT;
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?column?
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stop
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