-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 01/12/2009, at 10:15 AM, whoismario wrote: > The DBMS is MySQL. I don't know if it has a good optimizer or not, > but it's probably the DBMS of choice for many DM users.
Unfortunately true. Its optimiser technology is worse than what the commercial DBMSs abandoned in 1985, and Oracle will ensure that it never gets close to threatening the enterprise products. Clifford Heath. > > On Nov 30, 5:53 pm, Clifford Heath <[email protected]> wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> On 01/12/2009, at 9:43 AM, whoismario wrote: >> >>> I'd like back up Gary's concern on this. >>> A finder through association query on my server (using 0.9.11) does >>> not include the GROUP BY clause and takes less than half a second >>> while on my development machine (using 0.10.1) the same query takes >>> over 10 seconds. >> >> I'd bet you're missing a required index. And a DBMS with a proper >> optimiser. >> >> Is recruiters.team_id indexed? It needs to be. >> >> Clifford Heath. >> >> >> >>> Is it possible to remove the GROUP BY clause? >> >>> Thanks, >>> Jon >> >>> On Nov 3, 2:36 pm, Gary Yngve <[email protected]> wrote: >>>> A Recruiter belongs to a Team. >> >>>> Suppose I do >> >>>> Recruiter.first(:team_id => 'foo') >> >>>> That generates a simple query: >>>> ~ (0.002456) SELECT `id`, `created_at`, `updated_at`, ... `team_id` >>>> FROM `recruiters` WHERE `team_id` = 'foo' ORDER BY `id` LIMIT 1 >> >>>> Now suppose I do: >>>> Recruiter.first('team.id' => 'foo') >> >>>> That generates: >>>> ~ (0.008210) SELECT `recruiters`.`id`, `recruiters`.`created_at`, >>>> `recruiters`.`updated_at`, ... `recruiters`.`team_id` FROM >>>> `recruiters` INNER JOIN `teams` ON `recruiters`.`team_id` = >>>> `teams`.`id` WHERE `teams`.`id` = '554'GROUPBY `recruiters`.`id`, >>>> `recruiters`.`created_at`, `recruiters`.`updated_at`, ... >>>> `recruiters`.`team_id` ORDER BY `recruiters`.`id` LIMIT 1 >> >>>> What I don't understand is why doesn't the second query just do: >> >>>> ~ (0.008210) SELECT `recruiters`.`id`, `recruiters`.`created_at`, >>>> `recruiters`.`updated_at`, ... `recruiters`.`team_id` FROM >>>> `recruiters` INNER JOIN `teams` ON `recruiters`.`team_id` = >>>> `teams`.`id` WHERE `teams`.`id` = '554' ORDER BY `recruiters`.`id` >>>> LIMIT 1 >> >>>> ? >> >>>> For that matter, are there any underlying efficiency concerns in >>>> the >>>> DB regarding the superfluous group_by? >> >>>> Thanks, >>>> Gary >> >>> -- >> >>> You received this message because you are subscribed to the Google >>> Groups "DataMapper" group. >>> To post to this group, send email to [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected] >>> . >>> For more options, visit this group >>> athttp://groups.google.com/group/datamapper?hl=en >>> . >> >> -----BEGIN PGP SIGNATURE----- >> Version: GnuPG v1.4.9 (Darwin) >> >> iEYEARECAAYFAksUTNYACgkQROuaL1tmAEZqmgCeMH27oWFflIg6upsAtpJ+HJ5t >> fiQAn1Oi2LSPYE2d66x+7U6aa0yCn7I3 >> =krCm >> -----END PGP SIGNATURE----- > > -- > > You received this message because you are subscribed to the Google > Groups "DataMapper" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected] > . > For more options, visit this group at > http://groups.google.com/group/datamapper?hl=en > . > > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (Darwin) iEYEARECAAYFAksUVfYACgkQROuaL1tmAEaE3wCbBfzrV8+0GtFrFAcQigZR1xX0 xxQAn0Pa8ppT/cIjXS/VpattXTDrqrgs =7T0W -----END PGP SIGNATURE----- -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
