maria-discuss team mailing list archive

[MARK CALLAGHAN <mdcallag@xxxxxxxxx>]

On Sat, Jun 15, 2013 at 7:27 AM, Michael Widenius <monty@xxxxxxxxxxxx>wrote:

>
> MARK>
> http://bazaar.launchpad.net/~mysqlatfacebook/mysqlatfacebook/5.1/revision/3652
>
> MARK> Port tmp_table_max_file_size option from the Google patch to limit
> max size of
> MARK> on-disk temp tables.  This adds the my.cnf option and session
> variable
> MARK> "tmp_table_max_file_size" to limit the max size of an on-disk
> (MyISAM)
> MARK> temp table.
> MARK> The error ER_TMP_TABLE_MAX_FILE_SIZE_EXCEEDED is raised when the
> limit
> MARK> is exceeded.
>
> This code sets te same size for implicate and internal tmp tables.
>
> Mark, do you think we should have both variables availble?
> (It's similar amount of work to add two variables instead of one).


> I looked at the above patch (thanks for the link) and most of if looks
> good, but there is a few ways we can improve it when we apply it.
>

I am sure my patch can be improved. It changes code that I don't know much
about. I think it is better to use separate variables for implicit vs
explicit temp tables. But the behavior that is most needed is 1) better
behavior when the filesystem is full during temp table writes and 2) maybe
a global limit on the amount of disk space that can be used by temp tables.
Per-session limits might not prevent concurrent sessions from causing a
problem.

-- 
Mark Callaghan
mdcallag@xxxxxxxxx