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" <mdcallag@gmail.com> 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
<timour@montyprogram.com> wrote:
>>
>> Hi!
>>
>>>>>>> "MARK" == MARK CALLAGHAN<mdcallag@gmail.com>  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     : maria-developers@lists.launchpad.net
>> Unsubscribe : https://launchpad.net/~maria-developers
>> More help   : https://help.launchpad.net/ListHelp



--
Mark Callaghan
mdcallag@gmail.com

_______________________________________________
Mailing list: https://launchpad.net/~maria-developers
Post to     : maria-developers@lists.launchpad.net
Unsubscribe : https://launchpad.net/~maria-developers
More help   : https://help.launchpad.net/ListHelp