Maybe it has a confusing name, but EMPTY_QUERIES should count the number of SELECT statements that return 0 rows. For me that has been a useful indicator for inefficient applications. On Fri, May 17, 2013 at 11:33 AM, Ian Gilfillan <launchpad@greenman.co.za>wrote:

I'm documenting the status variables at the moment, and have a question about Empty_queries vs Com_empty_queries.

Com_empty_queries is not incremented when an empty result is returned, and appears to be incremented only when an empty query is sent to the server, eg:

mysql --comments -e '-- sql comment'

Empty_queries appears to match the empty queries returned with SHOW USER_STATISTICS. It increments each time a query is performed that returns an empty result.

Currently the documentation on the user statistics page at https://kb.askmonty.org/en/**user-statistics/<https://kb.askmonty.org/en/user-statistics/>says that EMPTY_QUERIES (and therefore the Empty_queries status variable) is "The number of times this user's connections sent empty queries to the server", which would describe Com_empty_queries rather than Empty_queries, and would need to be corrected.

The documentation on https://kb.askmonty.org/en/**server-status-variables/<https://kb.askmonty.org/en/server-status-variables/>is what I've just written based on the above.

Have I understood this correctly, or is there something else to it?

thanks, ian

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