Question

I have a webapp that lets you run querys from a DB using a simple textarea in a form. I have one problem:

I need to check the query memory consumption before it runs (so it won’t crash my server).

Is there a way using PHP or MySQL to do that?

For example, i have 3 tables:

News (idNews,created,idMedio,state)
NewsAreaMain (idNewsAreaMain,idNews,idAreaMain)
AreaMain (idAreaMain)

and someone tried the following query that actually crashed the server:

SELECT DISTINCT News.* 
FROM NewsAreaMain, News 
WHERE 
    (
        (
            NewsAreaMain.idNews=News.idNews 
            AND News.idNews IN 
                (
                    SELECT DISTINCT News.idNews 
                    FROM News, NewsAreaMain 
                    WHERE NewsAreaMain.idNews=News.idNews 
                    AND NewsAreaMain.idAreaMain="1"
                 )
        ) 
    AND idMedio="5" 
    OR ( idMedio="6" )
    )
AND News.state=1 
ORDER BY created DESC 
LIMIT 0, 20;

Answer 1

Not that I know of. If there were one, I’m sure all the shared hosting sites out there would use it and block queries that are too intensive rather than using such a dirty method as killing queries that run too long.

That would probably be your only option. Have a process that periodically checked the first entry in SHOW PROCESSLIST, and if “Time” is above a certain value (it’s in seconds, so 10 would probably be an ok, if tight, value. Anything above 60 is asking for trouble), kill it with KILL QUERY ##### (using the relevant ID number returned as part of SHOW PROCESSLIST).