I ran this select from information_schema to get the count of a table with aprox... | Hacker News

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jakejake on June 5, 2012 | parent | context | favorite | on: Loading half a billion rows into MySQL

I ran this select from information_schema to get the count of a table with aprox 1.2 million rows. each time I run the query, though, the number returned is different. it seems to vary by about 200k either way. does anybody know why that would be happening?

kristjan on June 5, 2012 [–]

It's just an estimate for the query engine, not a true row count. But good enough for a progress bar.

From http://dev.mysql.com/doc/refman/5.0/en/tables-table.html:

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

fizx on June 6, 2012 | | [–]

If you run it a dozen times, it converges on the truth.

jakejake on June 5, 2012 | | [–]

aha, thanks

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