mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-18 13:43:24 +02:00
7259736a6e
Instead of serializing the transaction to disk after reaching the logical_decoding_work_mem limit in memory, we consume the changes we have in memory and invoke stream API methods added by commit45fdc9738b. However, sometimes if we have incomplete toast or speculative insert we spill to the disk because we can't generate the complete tuple and stream. And, as soon as we get the complete tuple we stream the transaction including the serialized changes. We can do this incremental processing thanks to having assignments (associating subxact with toplevel xacts) in WAL right away, and thanks to logging the invalidation messages at each command end. These features are added by commits0bead9af48andc55040ccd0respectively. Now that we can stream in-progress transactions, the concurrent aborts may cause failures when the output plugin consults catalogs (both system and user-defined). We handle such failures by returning ERRCODE_TRANSACTION_ROLLBACK sqlerrcode from system table scan APIs to the backend or WALSender decoding a specific uncommitted transaction. The decoding logic on the receipt of such a sqlerrcode aborts the decoding of the current transaction and continue with the decoding of other transactions. We have ReorderBufferTXN pointer in each ReorderBufferChange by which we know which xact it belongs to. The output plugin can use this to decide which changes to discard in case of stream_abort_cb (e.g. when a subxact gets discarded). We also provide a new option via SQL APIs to fetch the changes being streamed. Author: Dilip Kumar, Tomas Vondra, Amit Kapila, Nikhil Sontakke Reviewed-by: Amit Kapila, Kuntal Ghosh, Ajin Cherian Tested-by: Neha Sharma, Mahendra Singh Thalor and Ajin Cherian Discussion: https://postgr.es/m/688b0b7f-2f6c-d827-c27b-216a8e3ea700@2ndquadrant.com
31 lines
1.3 KiB
PL/PgSQL
31 lines
1.3 KiB
PL/PgSQL
SET synchronous_commit = on;
|
|
SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
|
|
|
|
CREATE TABLE stream_test(data text);
|
|
|
|
-- consume DDL
|
|
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
|
|
|
|
-- streaming test with sub-transaction
|
|
BEGIN;
|
|
savepoint s1;
|
|
SELECT 'msg5' FROM pg_logical_emit_message(true, 'test', repeat('a', 50));
|
|
INSERT INTO stream_test SELECT repeat('a', 2000) || g.i FROM generate_series(1, 35) g(i);
|
|
TRUNCATE table stream_test;
|
|
rollback to s1;
|
|
INSERT INTO stream_test SELECT repeat('a', 10) || g.i FROM generate_series(1, 20) g(i);
|
|
COMMIT;
|
|
|
|
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'include-xids', '0', 'stream-changes', '1');
|
|
|
|
-- streaming test for toast changes
|
|
ALTER TABLE stream_test ALTER COLUMN data set storage external;
|
|
-- consume DDL
|
|
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');
|
|
|
|
INSERT INTO stream_test SELECT repeat('a', 6000) || g.i FROM generate_series(1, 10) g(i);
|
|
SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL,NULL, 'include-xids', '0', 'stream-changes', '1');
|
|
|
|
DROP TABLE stream_test;
|
|
SELECT pg_drop_replication_slot('regression_slot');
|