On 10/26/07, The Fearow fearow00@hotmail.com wrote:
Can we limit the amount of CPU/processing a query could take? If not, that would be a very useful MySQL function. We could then run those queries but expect them to take a lot longer.
It doesn't work that way, AFAIK. Using InnoDB, you would have to maintain a transaction for as long as the query runs. Many queries run simultaneously at low priority for a long time would therefore probably take a lot longer than if they were run quickly a few at a time, due to transactional overhead. InnoDB has to keep separate consistent copies for each query, more or less, which I suppose must involve copy-on-write -- needless to say, that slows down every write considerably if you have many transactions open. (In MyISAM, of course, it would be even worse: you would take out a read lock and prevent changes altogether.)