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--
-- Test Statistics Collector
--
-- Must be run after tenk2 has been created (by create_table),
-- populated (by create_misc) and indexed (by create_index).
--
-- conditio sine qua non
SHOW stats_start_collector; -- must be on
stats_start_collector
-----------------------
on
(1 row)
-- save counters
CREATE TEMP TABLE prevstats AS
SELECT t.seq_scan, t.seq_tup_read, t.idx_scan, t.idx_tup_fetch,
(b.heap_blks_read + b.heap_blks_hit) AS heap_blks,
(b.idx_blks_read + b.idx_blks_hit) AS idx_blks
FROM pg_catalog.pg_stat_user_tables AS t,
pg_catalog.pg_statio_user_tables AS b
WHERE t.relname='tenk2' AND b.relname='tenk2';
-- enable statistics
SET stats_block_level = on;
SET stats_row_level = on;
-- helper function
CREATE FUNCTION sleep(interval) RETURNS integer AS '
DECLARE
endtime timestamp;
BEGIN
endtime := timeofday()::timestamp + $1;
WHILE timeofday()::timestamp < endtime LOOP
END LOOP;
RETURN 0;
END;
' LANGUAGE 'plpgsql';
-- do something
SELECT count(*) FROM tenk2;
count
-------
10000
(1 row)
SELECT count(*) FROM tenk2 WHERE unique1 = 1;
count
-------
1
(1 row)
-- let stats collector catch up
SELECT sleep('0:0:2'::interval);
sleep
-------
0
(1 row)
-- check effects
SELECT st.seq_scan >= pr.seq_scan + 1,
st.seq_tup_read >= pr.seq_tup_read + cl.reltuples,
st.idx_scan >= pr.idx_scan + 1,
st.idx_tup_fetch >= pr.idx_tup_fetch + 1
FROM pg_stat_user_tables AS st, pg_class AS cl, prevstats AS pr
WHERE st.relname='tenk2' AND cl.relname='tenk2';
?column? | ?column? | ?column? | ?column?
----------+----------+----------+----------
t | t | t | t
(1 row)
SELECT st.heap_blks_read + st.heap_blks_hit >= pr.heap_blks + cl.relpages,
st.idx_blks_read + st.idx_blks_hit >= pr.idx_blks + 1
FROM pg_statio_user_tables AS st, pg_class AS cl, prevstats AS pr
WHERE st.relname='tenk2' AND cl.relname='tenk2';
?column? | ?column?
----------+----------
t | t
(1 row)
-- clean up
DROP FUNCTION sleep(interval);
-- End of Stats Test
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