i came across a strange phenomenon, and i hope, that someone can explain this to me:

i have a some "static" tables (they change once per day).

mysql> select 'appObjectGroups' as tbl, count(*) as num from appObjectGroups

union select 'appObjectDependencies' as tbl, count(*) as num from appObjectDependencies

union select 'appObjectUrls' as tbl, count(*) as num from appObjectUrls

union select 'appObjectValues' as tbl, count(*) as num from appObjectValues

union select 'appObjects;' as tbl, count(*) as num from appObjects;

+-------------------------+------+

| tbl | num |

+-------------------------+------+

| appObjectGroups | 1149 |

| appObjectDependencies | 6885 |

| appObjectUrls | 1162 |

| appObjectValues | 3795 |

| appObjects; | 5409 |

+-------------------------+------+

5 rows in set (0.00 sec)

mysql> select table_name as tbl, table_rows as num from information_schema.tables where table_schema='mySchema' and table_name like 'app%';

+-------------------------+------+

| tbl | num |

+-------------------------+------+

| appObjectGroups | 1141 |

| appObjectDependencies | 6153 |

| appObjectUrls | 1141 |

| appObjectValues | 3584 |

| appObjects | 6061 |

+-------------------------+------+

5 rows in set (0.01 sec)

so how come that table_rows report something different than count(*)?

and more important to me: which one is correct? :-)

解决方案

Quoting from documentation:

For InnoDB tables, the row count is only a rough estimate used in SQL

optimization. (This is also true if the InnoDB table is partitioned.)