sql - 获取 Postgres 数据库中每个表的行数

Question

获取数据库中所有表的行数的最有效方法是什么？

我正在使用 Postgres 数据库。

示例结果

table_name     row_count
------------   -------------
some_table     1,234
foobar         5,678
another_table  32
... 

Answer 1

如果你想要一个特定表的行数那么它就可以了

SELECT reltuples FROM pg_class WHERE oid = 'my_schema.my_table'::regclass;

reltuples is a column from pg_class table, it holds data about "number of rows >in the table. This is only an estimate used by the planner.

如果您想要一个包含所有表及其行数的列表，那么它就可以完成

SELECT
  pgClass.relname   AS tableName,
  pgClass.reltuples AS rowCount
FROM
  pg_class pgClass
INNER JOIN
  pg_namespace pgNamespace ON (pgNamespace.oid = pgClass.relnamespace)
WHERE
  pgNamespace.nspname NOT IN ('pg_catalog', 'information_schema') AND
  pgClass.relkind='r'

"Why is "SELECT count(*) FROM bigtable;" slow?" : count(*)