Ken, I think the main issue here is described in the InnoDB docs: "You should note that it does not make sense to increase the index sample size, then run ANALYZE TABLE and decrease sample size to attempt to obtain better statistics. This is because the statistics are not persistent. They are automatically recalculated at various times other than on execution of ANALYZE TABLE. Sooner or later the “better” statistics calculated by ANALYZE running with a high value of innodb_stats_sample_pages will be wiped away."
"Although it is not possible to specify the sample size on a per-table basis, smaller tables generally would require fewer index samples than larger tables require. If your database has many large tables, you may want to consider using a higher value for innodb_stats_sample_pages than if you have mostly smaller tables." So we have control over how hard InnoDB tries when it does try but we don't have any control over when it decides or how it decides to try (though as of 1.0.2 we can disable it for interactive users--does Drizzle even differentiate between them?). That can lead to some uneasy situations when you've had to increase the variable significantly (very large table) but you don't want that sampling to occur Jeremy On Fri, Jul 31, 2009 at 12:55 AM, [email protected] < [email protected]> wrote: > There us in the InnoDB Plugin a parameter to control the number of index > dives, and a bug fix for 64-bit machines regarding sampling. > > Chech the doc on InnoDB.com. > > Ken > Sent from my iPhone > > > On Jul 31, 2009, at 1:46 AM, dormando <[email protected]> wrote: > > I tend to issue this about once a week against production... Usually if >> something flips around more than once we push out a USE INDEX hint and >> bury it though. >> >> If there's any way to improve the sampling, or optionally disable it, >> that'd be a big help. Systems like TheSchwartz tend to go from empty to >> full in a weird way and back again often, which break the query plan >> almost consistently. >> >> -Dormando >> >> On Thu, 30 Jul 2009, Brian Aker wrote: >> >> Hi! >>> >>> What experiences have people had with ANALYZE TABLE? Tinkering around >>> with it >>> I am wondering if anyone ever uses this with Innodb with any >>> satisfaction. >>> >>> Cheers, >>> -Brian >>> >>> >>> _______________________________________________ >>> Mailing list: https://launchpad.net/~drizzle-discuss >>> Post to : [email protected] >>> Unsubscribe : https://launchpad.net/~drizzle-discuss >>> More help : https://help.launchpad.net/ListHelp >>> >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~drizzle-discuss >> Post to : [email protected] >> Unsubscribe : https://launchpad.net/~drizzle-discuss >> More help : https://help.launchpad.net/ListHelp >> > > _______________________________________________ > Mailing list: https://launchpad.net/~drizzle-discuss > Post to : [email protected] > Unsubscribe : https://launchpad.net/~drizzle-discuss > More help : https://help.launchpad.net/ListHelp >
_______________________________________________ Mailing list: https://launchpad.net/~drizzle-discuss Post to : [email protected] Unsubscribe : https://launchpad.net/~drizzle-discuss More help : https://help.launchpad.net/ListHelp
