postgresql查询慢的排查脚本

以下是一个简化的PostgreSQL查询慢排查脚本示例：

-- 查询最消耗CPU时间的查询
SELECT pid, usename, datname, query, state, query_start, now() - query_start AS duration,
       round(cpu_time / 1000.0) AS cpu_sec,
       round(memory_usage / 1024.0) AS memory_mb
FROM pg_stat_activity
WHERE state = 'active' AND query NOT ILIKE '%pg_stat_activity%'
ORDER BY cpu_time DESC
LIMIT 5;
 
-- 查询最长运行时间的查询
SELECT pid, usename, datname, query, state, query_start, now() - query_start AS duration,
       round(cpu_time / 1000.0) AS cpu_sec,
       round(memory_usage / 1024.0) AS memory_mb
FROM pg_stat_activity
WHERE state = 'active' AND query NOT ILIKE '%pg_stat_activity%'
ORDER BY duration DESC
LIMIT 5;
 
-- 查询正在等待锁的查询
SELECT pid, usename, datname, query, state, query_start, now() - query_start AS duration,
       waiting, waiting_reason
FROM pg_stat_activity
WHERE waiting = 't' AND query NOT ILIKE '%pg_stat_activity%'
ORDER BY query_start DESC
LIMIT 5;
 
-- 查询最消耗磁盘I/O的查询
-- 需要使用pg_stat_statements扩展来获取更详细的信息
SELECT * FROM pg_stat_statements ORDER BY blk_read_time DESC LIMIT 5;

这个脚本提供了几个关键的查询，用于检测PostgreSQL中可能导致查询变慢的几个关键因素：活跃查询中最消耗CPU时间的、最长运行时间的查询、正在等待锁的查询以及最消耗磁盘I/O的查询。这些查询可以帮助数据库管理员快速定位和解决性能问题。