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rake db:migrate queries the schema_migrations table many times (unnecessarily?)
Reported by Jeremy Weiskotten | August 25th, 2008 @ 04:59 PM | in 2.x
Here's the log when running "rake db:migrate" when there are 4 migrations in the db/migrate folder (all have already been run).
SQL (0.008272) SELECT version FROM schema_migrations
SQL (0.000360) SELECT version FROM schema_migrations
SQL (0.000286) SELECT version FROM schema_migrations
SQL (0.000271) SELECT version FROM schema_migrations
Migrating to CreateSessions (20080812190111)
SQL (0.000289) SELECT version FROM schema_migrations
Migrating to CreateUsers (20080812190627)
SQL (0.000256) SELECT version FROM schema_migrations
Migrating to AddDefaultUser (20080812205823)
SQL (0.000256) SELECT version FROM schema_migrations
Migrating to AddUsersAdmin (20080813112503)
SQL (0.000266) SELECT version FROM schema_migrations
SQL (0.000309) SELECT version FROM schema_migrations
It appears to be fetching the list of versions once per migration file found in db/migrate, and then some.
This isn't too bad with only a handful of migrations, but older, larger projects with hundreds of migrations can take a while to run, even if you're up to date. The db:migrate task could be smarter and only fetch the versions once at start.
Comments and changes to this ticket
-
Tarmo Tänav August 26th, 2008 @ 03:00 AM
- Tag set to “activerecord, migrations”
Please test the attached patch
-
Repository August 26th, 2008 @ 06:04 AM
- State changed from “new” to “resolved”
- Tag changed from “activerecord, migrations” to “activerecord, migrations, patch”
(from [3d2ac918b987ef0cff34f6a7fdd20926b7a9e5d9]) Cache migrated versions list in Migrator and use it to fetch the latest migrated version name [#845 state:resolved]
Also optimized Migrator#current_version class method to fetch only the latest version number and not all of them.
With this change no matter how many migrations there are the schema_migrations table is only SELECTed from once.
Signed-off-by: Jeremy Kemper jeremy@bitsweat.net http://github.com/rails/rails/co...
-
Repository August 26th, 2008 @ 06:04 AM
(from [7d2b72f3ae6f92e61d131349c4580be0d1dd12ca]) Cache migrated versions list in Migrator and use it to fetch the latest migrated version name [#845 state:resolved]
Also optimized Migrator#current_version class method to fetch only the latest version number and not all of them.
With this change no matter how many migrations there are the schema_migrations table is only SELECTed from once.
Signed-off-by: Jeremy Kemper jeremy@bitsweat.net http://github.com/rails/rails/co...
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Jeremy Weiskotten
Tarmo Tänav
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845
rake db:migrate queries the schema_migrations table many times (unnecessarily?)
(from [3d2ac918b987ef0cff34f6a7fdd20926b7a9e5d9]) Cache m...
-
845
rake db:migrate queries the schema_migrations table many times (unnecessarily?)
(from [7d2b72f3ae6f92e61d131349c4580be0d1dd12ca]) Cache m...