id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
24203	Optimisation: adding multiple fields to same model should attempt to run single ALTER TABLE statement	Peter Lauri	nobody	"Origin: https://groups.google.com/d/msg/django-users/DDekrNgXH2U/k1un-e8CbnMJ

When adding multiple fields to a Model the makemigrate and migrate does not attempt to create one ALTER TABLE statement, but rather one per field added. This can cause slow migrations of large tables.

I propose to optimise to attempt to merge multiple AddField to one single ALTER TABLE request when the migrate is run.

My real world case the db backend was MySQL, here is PG example of 2nd migration db output after adding two fields to one model.

{{{
  Applying play.0002_auto_20150122_1825...DEBUG ALTER TABLE ""play_play"" ADD COLUMN ""field2"" varchar(100) NULL; (params [])
DEBUG (0.000) ALTER TABLE ""play_play"" ADD COLUMN ""field2"" varchar(100) NULL; args=[]
DEBUG ALTER TABLE ""play_play"" ALTER COLUMN ""field2"" DROP DEFAULT; (params [])
DEBUG (0.000) ALTER TABLE ""play_play"" ALTER COLUMN ""field2"" DROP DEFAULT; args=[]
DEBUG ALTER TABLE ""play_play"" ADD COLUMN ""field3"" varchar(100) NULL; (params [])
DEBUG (0.000) ALTER TABLE ""play_play"" ADD COLUMN ""field3"" varchar(100) NULL; args=[]
DEBUG ALTER TABLE ""play_play"" ALTER COLUMN ""field3"" DROP DEFAULT; (params [])
DEBUG (0.000) ALTER TABLE ""play_play"" ALTER COLUMN ""field3"" DROP DEFAULT; args=[]
}}}"	Cleanup/optimization	new	Migrations	dev	Normal		migration	Markus Holtermann ambivalentno dharris+django@… emorley@… Phil Krylov Adam Johnson elonzh	Someday/Maybe	0	0	0	0	0	0