How to log queries with large number of results

Question

I've been programming a website in Drupal for years now, and sometimes I notice things in the code where I'm querying for only one row, but I forget to use a LIMIT so the result set can get unnecessarily large.

While the best way to avoid this problem is to simply not forget this step for these types of queries, I am still human, so it's unrealistically optimistic for the long-term.

I'd like to reduce as much as possible the amount of data transferred between MySQL and PHP, and to do that I need to know which queries return large result sets so I can find them in the code and make the appropriate fixes.

I know there is a slow query log, but queries with large result sets are not necessarily slow.

Is there any easy way to do this using a Drupal hook or otherwise?

Answer 1

You can use devel module to show the queries being executed on the page.

After enabling the module, go to Administration > Configuration > Development > Devel Settings and make sure that Display query log is on. You should see the query log at the bottom of your pages.