SQL 查询来查看 PostgreSQL的各连接数

用 SQL 查询来查看 PostgreSQL 的最大连接数和当前连接数。

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1. 查看最大连接数

SHOW max_connections;

或者

SELECT setting AS max_connections FROM pg_settings WHERE name = 'max_connections';

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2. 查看当前连接数

SELECT count(*) AS current_connections FROM pg_stat_activity;

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3. 一起查看

你可以把两个信息合并到一条 SQL：

SELECT (SELECT setting::int FROM pg_settings WHERE name = 'max_connections') AS max_connections,(SELECT count(*) FROM pg_stat_activity) AS current_connections;

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4. 查看每个数据库的连接数

SELECT datname, count(*) AS connections
FROM pg_stat_activity
GROUP BY datname
ORDER BY connections DESC;

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5. 查看每个用户的连接数

SELECT usename, count(*) AS connections
FROM pg_stat_activity
GROUP BY usename
ORDER BY connections DESC;

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