活动连接数和剩余连接数

Question

我想获得有关一段时间内连接峰值数量的统计信息。

我知道这种pg_stat_activity观点，就像select count(*) from pg_stat_activity，但我认为这种方法不是很聪明。

是否有其他视图或表格可以提供我需要的信息？

Answer 1

此 SQL 将帮助您

select max_conn,used,res_for_super,max_conn-used-res_for_super res_for_normal 
from 
  (select count(*) used from pg_stat_activity) t1,
  (select setting::int res_for_super from pg_settings where name=$$superuser_reserved_connections$$) t2,
  (select setting::int max_conn from pg_settings where name=$$max_connections$$) t3

结果：

max_conn | used | res_for_super | res_for_normal 
---------+------+---------------+----------------
  100    |    2 |             3 |             95
(1 row)

你可以把它放在shell中：

#!/bin/bash
for (( c=1; c<=3600; c++ ))
do
     gsql -U pgdba -W pgdba -p 6432 -c "sql" >> /home/pgdba/res_data.log
     sleep 1  # once per second
done

或者您可以将结果记录到表格中，然后执行

postgres=# copy restbl to '/home/pgdba/res.csv' csv header;

获取结果 csv 文件。