Is there a way to get rows_examined in MySQL without the slow log?

Question

I\'m building some profile information for a home grown app. I\'d like the debug page to show the query sent along with how many rows were examined without assuming that slo

Answer 1

It's slightly better than it was in 2006. You can issue SHOW SESSION STATUS before and after and then look at each of the Handler_read_* counts in order to be able to tell the number of rows examined.

There's really no other way.. While the server protocol has a flag to say if a table scan occurred, it doesn't expose rows_examined. Even tools like MySQL's Query Analyzer have to work by running SHOW SESSION STATUS before/after (although I think it only runs SHOW SESSION STATUS after, since it remembers the previous values).

I know it's not related to your original question, but there are other expensive components to queries besides rows_examined. If you choose to do this via the slow log, you should check out this patch:

http://www.percona.com/docs/wiki/patches:microslow_innodb#changes_to_the_log_format

I can recommend looking for "Disk_tmp_table: Yes" and "Disk_filesort: Yes".