在 MySQL 中获取表的行数？
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Getting row count for a table in MySQL?
提问by Quassnoi
Can anyone tell me which is he better appraoch in MySQL whin it comes to finding the row count of a table: is it better to do
任何人都可以告诉我在查找表的行数时，他在 MySQL 中哪个更好的方法：这样做更好吗？
SELECT COUNT(*) FROM TABLE_NAME
or to look up the row count in the table TABLEin the INFORMATION_SCHEMA?
或查找表TABLE中的行数INFORMATION_SCHEMA？
This would be a frequent operation for calculating pagination counts for pages?
这将是计算页面分页计数的频繁操作？
I should add that tables will only have a few thousand rows at most.
我应该补充一点，表最多只有几千行。
Thanks
谢谢
Martin O'Shea.
马丁·奥谢。
回答by Quassnoi
In MyISAM, this query:
在MyISAM，这个查询：
SELECT COUNT(*)
FROM TABLE_NAME
is instant, since it's kept in the table metadata, so it's almost free to issue this query and it will always get the correct result.
是即时的，因为它保存在表元数据中，所以几乎可以自由地发出这个查询并且它总是会得到正确的结果。
In InnoDB, this query will count rows one-by-one which could take some time.
在 中InnoDB，此查询将一一计算行数，这可能需要一些时间。
So if you don't need exact value of COUNT(*), you may query INFORMATION_SCHEMA.
因此，如果您不需要 的确切值COUNT(*)，您可以查询INFORMATION_SCHEMA。
回答by Jason Shah
I'd also consider using SQL_CALC_FOUND_ROWSand SELECT FOUND_ROWS()if you find COUNT(*)too slow.
我还考虑使用SQL_CALC_FOUND_ROWS和SELECT FOUND_ROWS()如果你发现COUNT(*)太慢。
