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
23505	unique constraint tracking lost after DropColumn + AddColumn in postgres	Andrew Fink	nobody	"Reproduce:
1. Create model with a multi-column uniqueness constraint in postgres
2. Drop a column in the uniqueness constraint, then readd it with a different type.
e.g:
{{{#!python
foo = models.IntegerField()
# to
foo = models.CharField(max_length=255)
}}}
3. Attempt to modify the uniqueness constraint and run the subsequent migration. It fails with 'ValueError: Found wrong number (0) of constraints for <tablename>' 

This is likely due to django not tracking postgres automatically dropping the uniqueness constraint when a column is deleted/added.
See 'Description -> DROP COLUMN':
http://www.postgresql.org/docs/9.1/static/sql-altertable.html
"	Bug	closed	Migrations	1.7	Normal	needsinfo	unique_together		Unreviewed	0	0	0	0	0	0