This looks like a good alternative to the load shedding scripts that a lot of people run. On Dec 21, 2011 10:02 AM, "MARK CALLAGHAN" <[email protected]> wrote:
> A warning would be excellent. An error would be a problem. Returning > OK is probably not the best result when the examined limit is reached. > > On Wed, Dec 21, 2011 at 7:17 AM, Timour Katchaounov > <[email protected]> wrote: > >> > >> Hi! > >> > >>>>>>> "MARK" == MARK CALLAGHAN<[email protected]> writes: > >> > >> > >> MARK> I want a variant of the LIMIT clause that limits the number of > rows > >> MARK> examined during SELECT processing. This should return OK when the > >> MARK> limit is reached -- something like NESTED_LOOP_QUERY_LIMIT. While > >> MARK> LIMIT can be LIMIT x and LIMIT x,y. This only supports one > argument > >> -- > >> MARK> LIMIT_ROWS_EXAMINED x. Are you interested in implementing this > >> feature > >> MARK> for me? We will sponsor the work. The purpose of the feature is > to > >> MARK> prevent queries from taking too long when there isn't a great > index > >> MARK> and many rows might be filtered. > >> > >> I am a bit afraid of returning 'ok'. Would it not be better to return > >> an error? > >> > >> Another option would be to generate a warning so that the application > >> can know that they didn't get all rows. > > > > > > This is what I would prefer to do: > > - process the new LIMIT_ROWS_EXAMINED clause in the same way as LIMIT, > > just with a different condition to end query execution, > > - in addition produce a warning that not all rows were returned. > > > > Mark, does the above suit you? If you don't want to check for > > warnings, you can skip them, however users will have the option > > to detect that not all rows were returned. > > > > Timour > > > >> > >> We can do this and it should be relatively easy to do. > >> > >> Regards, > >> Monty > >> > >> _______________________________________________ > >> Mailing list: https://launchpad.net/~maria-developers > >> Post to : [email protected] > >> Unsubscribe : https://launchpad.net/~maria-developers > >> More help : https://help.launchpad.net/ListHelp > > > > -- > Mark Callaghan > [email protected] > > _______________________________________________ > Mailing list: https://launchpad.net/~maria-developers > Post to : [email protected] > Unsubscribe : https://launchpad.net/~maria-developers > More help : https://help.launchpad.net/ListHelp >
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