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already collected in the current transaction; this allows plpgsql functions to watch for stats updates even though they are confined to a single transaction. Use this instead of the previous kluge involving pg_stat_file() to wait for the stats collector to update in the stats regression test. Internally, decouple storage of stats snapshots from transaction boundaries; they'll now stick around until someone calls pgstat_clear_snapshot --- which xact.c still does at transaction end, to maintain the previous behavior. This makes the logic a lot cleaner, at the price of a couple dozen cycles per transaction exit.
78 lines
2.4 KiB
PL/PgSQL
78 lines
2.4 KiB
PL/PgSQL
--
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-- Test Statistics Collector
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--
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-- Must be run after tenk2 has been created (by create_table),
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-- populated (by create_misc) and indexed (by create_index).
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--
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-- conditio sine qua non
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SHOW stats_start_collector; -- must be on
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-- wait to let any prior tests finish dumping out stats;
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-- else our messages might get lost due to contention
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SELECT pg_sleep(2.0);
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-- save counters
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CREATE TEMP TABLE prevstats AS
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SELECT t.seq_scan, t.seq_tup_read, t.idx_scan, t.idx_tup_fetch,
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(b.heap_blks_read + b.heap_blks_hit) AS heap_blks,
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(b.idx_blks_read + b.idx_blks_hit) AS idx_blks
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FROM pg_catalog.pg_stat_user_tables AS t,
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pg_catalog.pg_statio_user_tables AS b
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WHERE t.relname='tenk2' AND b.relname='tenk2';
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-- function to wait for counters to advance
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create function wait_for_stats() returns void as $$
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declare
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start_time timestamptz := clock_timestamp();
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updated bool;
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begin
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-- we don't want to wait forever; loop will exit after 30 seconds
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for i in 1 .. 300 loop
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-- check to see if indexscan has been sensed
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SELECT (st.idx_scan >= pr.idx_scan + 1) INTO updated
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FROM pg_stat_user_tables AS st, pg_class AS cl, prevstats AS pr
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WHERE st.relname='tenk2' AND cl.relname='tenk2';
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exit when updated;
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-- wait a little
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perform pg_sleep(0.1);
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-- reset stats snapshot so we can test again
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perform pg_stat_clear_snapshot();
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end loop;
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-- report time waited in postmaster log (where it won't change test output)
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raise log 'wait_for_stats delayed % seconds',
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extract(epoch from clock_timestamp() - start_time);
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end
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$$ language plpgsql;
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-- enable statistics
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SET stats_block_level = on;
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SET stats_row_level = on;
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-- do a seqscan
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SELECT count(*) FROM tenk2;
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-- do an indexscan
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SELECT count(*) FROM tenk2 WHERE unique1 = 1;
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-- wait for stats collector to update
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SELECT wait_for_stats();
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-- check effects
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SELECT st.seq_scan >= pr.seq_scan + 1,
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st.seq_tup_read >= pr.seq_tup_read + cl.reltuples,
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st.idx_scan >= pr.idx_scan + 1,
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st.idx_tup_fetch >= pr.idx_tup_fetch + 1
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FROM pg_stat_user_tables AS st, pg_class AS cl, prevstats AS pr
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WHERE st.relname='tenk2' AND cl.relname='tenk2';
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SELECT st.heap_blks_read + st.heap_blks_hit >= pr.heap_blks + cl.relpages,
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st.idx_blks_read + st.idx_blks_hit >= pr.idx_blks + 1
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FROM pg_statio_user_tables AS st, pg_class AS cl, prevstats AS pr
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WHERE st.relname='tenk2' AND cl.relname='tenk2';
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-- End of Stats Test
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