Hi, During performance tests it was mentioned that pgbench common results are being different from what pg_stat_statements provides.
PostgreSQL version 9.5.3, centos 7.2. First run after pg_stat_extension created and first pgbench run. *pgbench *-c 30 -T 300 -U postgres -P 10 -r -v > statement latencies in milliseconds: >> >> 0.003431 \set nbranches 1 * :scale >> >> 0.001046 \set ntellers 10 * :scale >> >> 0.000891 \set naccounts 100000 * :scale >> >> 0.001356 \setrandom aid 1 :naccounts >> >> 0.000938 \setrandom bid 1 :nbranches >> >> 0.000879 \setrandom tid 1 :ntellers >> >> 0.000974 \setrandom delta -5000 5000 >> >> 0.102258 BEGIN; >> >> 0.228744 UPDATE pgbench_accounts SET abalance = abalance + >>> :delta WHERE aid = :aid; >> >> 0.156087 SELECT abalance FROM pgbench_accounts WHERE aid = >>> :aid; >> >> 17.715645 UPDATE pgbench_tellers SET tbalance = tbalance + >>> :delta WHERE tid = :tid; >> >> 6.222220 UPDATE pgbench_branches SET bbalance = bbalance + >>> :delta WHERE bid = :bid; >> >> 0.294592 INSERT INTO pgbench_history (tid, bid, aid, >>> delta, mtime) VALUES (:tid, :bid, :aid, :delta, CURRENT_TIMESTAMP); >> >> 0.502843 END; >> >> *pg_stat_statements * Example 1 > query | UPDATE pgbench_accounts SET abalance = abalance + ? >>> WHERE aid = ?; >> >> calls | 118804 >> >> total_time | 5944.19700000145 >> >> min_time | 0.017 >> >> max_time | 146.501 >> >> mean_time | 0.0500336436483624 >> >> stddev_time | 0.860838186600729 >> >> rows | 118804 >> >> Example 2 > query | INSERT INTO pgbench_history (tid, bid, aid, delta, >> mtime) VALUES (?, ?, ?, ?, CURRENT_TIMESTAMP); > > calls | 118804 > > total_time | 16533.2040000006 > > min_time | 0.075 > > max_time | 1.583 > > mean_time | 0.139163698191979 > > stddev_time | 0.0342061695940176 > > rows | 118804 > > Could anybody explain why results are different? Where is an inaccuracy - in pg_stat_statements or pgbench? Thanks in advance.
