1.查找執行較慢的sql：
select* from pg_stat_statements；
2.根據操作系統的pid查找回話：
select d.query from pg_stat_activity d where pid=18707;
3.查詢慢sql：
SELECT query,calls,total_time,(total_time / calls) AS average,ROWS,
100.0 * shared_blks_hit / NULLIF (shared_blks_hit + shared_blks_read,0) AS hit_percent
FROM pg_stat_statements ORDER BY average DESC LIMIT 10;
4.重置pg_stat_statements表：
select pg_stat_statements_reset();
5.後續不斷更新。。。。。。。。。。