Well, this should be enough to get number of all records in current database:
SELECT SUM(TABLE_ROWS) FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA = DATABASE();
Surprisingly, I’m getting different numbers each time I execute above statement! First I thought there is a problem with my database. But it’s same for sample db provided by MySQL developers.
Executing above statement on the sakila multiple times results in this values:
46362
48104
45170
47060
48139
What I’m doing wrong? Is this a bug?
This is an InnoDB thing – you can instead count(id) on the table, but it’s slow.
Because it’s slow, InnoDB takes a random sample of rows, measures the sizes, then divides the total size to determine approx how many rows there are.