#28273: Have a way to prevent adding columns with defaults in migrations
-------------------------------------+-------------------------------------
Reporter: Raphael Gaschignard | Owner: nobody
Type: | Status: new
Cleanup/optimization |
Component: Migrations | Version: 1.10
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Raphael Gaschignard):
Adding a default after the column was added does not seem to trigger a
backfill. Like you're saying, creating two migrations doesn't cause this
issue to appear (except when custom fields add a default, for example)
{{{
testing=# select * from t;
a | b
----+---
hi | 3
hi | 4
hi | 5
(3 rows)
testing=# alter table t add column c integer null;
ALTER TABLE
testing=# select * from t;
a | b | c
----+---+---
hi | 3 |
hi | 4 |
hi | 5 |
(3 rows)
testing=# alter table t alter COLUMN c set default 3;
ALTER TABLE
testing=# select * from t;
a | b | c
----+---+---
hi | 3 |
hi | 4 |
hi | 5 |
(3 rows)
testing=# alter table t add column d integer null default 10;
ALTER TABLE
testing=# select * from t;
a | b | c | d
----+---+---+----
hi | 3 | | 10
hi | 4 | | 10
hi | 5 | | 10
(3 rows)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/28273#comment:4>
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