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This adds the statistics about total transactions count and total transaction data logically sent to the decoding output plugin from ReorderBuffer. Users can query the pg_stat_replication_slots view to check these stats. Suggested-by: Andres Freund Author: Vignesh C and Amit Kapila Reviewed-by: Sawada Masahiko, Amit Kapila Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de
92 lines
3.4 KiB
PL/PgSQL
92 lines
3.4 KiB
PL/PgSQL
-- predictability
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SET synchronous_commit = on;
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SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
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CREATE TABLE stats_test(data text);
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-- function to wait for counters to advance
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CREATE FUNCTION wait_for_decode_stats(check_reset bool, check_spill_txns bool) RETURNS void AS $$
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DECLARE
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start_time timestamptz := clock_timestamp();
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updated bool;
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BEGIN
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-- we don't want to wait forever; loop will exit after 30 seconds
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FOR i IN 1 .. 300 LOOP
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IF check_spill_txns THEN
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-- check to see if all updates have been reset/updated
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SELECT CASE WHEN check_reset THEN (spill_txns = 0)
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ELSE (spill_txns > 0)
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END
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INTO updated
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FROM pg_stat_replication_slots WHERE slot_name='regression_slot';
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ELSE
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-- check to see if all updates have been reset/updated
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SELECT CASE WHEN check_reset THEN (total_txns = 0)
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ELSE (total_txns > 0)
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END
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INTO updated
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FROM pg_stat_replication_slots WHERE slot_name='regression_slot';
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END IF;
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exit WHEN updated;
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-- wait a little
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perform pg_sleep_for('100 milliseconds');
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-- reset stats snapshot so we can test again
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perform pg_stat_clear_snapshot();
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END LOOP;
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-- report time waited in postmaster log (where it won't change test output)
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RAISE LOG 'wait_for_decode_stats delayed % seconds',
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extract(epoch from clock_timestamp() - start_time);
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END
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$$ LANGUAGE plpgsql;
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-- spilling the xact
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BEGIN;
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INSERT INTO stats_test SELECT 'serialize-topbig--1:'||g.i FROM generate_series(1, 5000) g(i);
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COMMIT;
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SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL, NULL, 'skip-empty-xacts', '1');
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-- Check stats, wait for the stats collector to update. We can't test the
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-- exact stats count as that can vary if any background transaction (say by
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-- autovacuum) happens in parallel to the main transaction.
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SELECT wait_for_decode_stats(false, true);
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SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots;
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-- reset the slot stats, and wait for stats collector to reset
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SELECT pg_stat_reset_replication_slot('regression_slot');
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SELECT wait_for_decode_stats(true, true);
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SELECT slot_name, spill_txns, spill_count, total_txns, total_bytes FROM pg_stat_replication_slots;
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-- decode and check stats again.
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SELECT count(*) FROM pg_logical_slot_peek_changes('regression_slot', NULL, NULL, 'skip-empty-xacts', '1');
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SELECT wait_for_decode_stats(false, true);
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SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots;
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SELECT pg_stat_reset_replication_slot('regression_slot');
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-- non-spilled xact
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INSERT INTO stats_test values(generate_series(1, 10));
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SELECT wait_for_decode_stats(false, false);
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SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots;
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-- Ensure stats can be repeatedly accessed using the same stats snapshot. See
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-- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
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BEGIN;
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SELECT slot_name FROM pg_stat_replication_slots;
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SELECT slot_name FROM pg_stat_replication_slots;
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COMMIT;
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DROP FUNCTION wait_for_decode_stats(bool, bool);
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DROP TABLE stats_test;
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SELECT pg_drop_replication_slot('regression_slot');
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