#35180: PostgreSQL pattern ops indexes are dropped when changing between
CharField
and TextField
-------------------------------------+-------------------------------------
Reporter: Robin Ray | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 5.0
(models, ORM) |
Severity: Normal | Resolution:
Keywords: index postgres | Triage Stage:
migration | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Robin Ray:
Old description:
> When converting an indexed CharField to a TextField (and vice versa) on
> PostgreSQL, Django drops the existing pattern ops `_like` index for the
> column but does not recreate it with the new pattern ops. When reversing
> the migration, Django does not recreate the initial `_like` index.
>
> I have been able to reproduce this behavior in Django 3.2 and 5.0.
>
> **Reproduction**
>
> 1. Given a model with a CharField that has `db_index=True` on a
> PostgreSQL database
> 2. Inspect the database indexes or migration SQL and see that the indexed
> CharField has two indexes, one of which ends in `_like` and uses
> `varchar_pattern_ops`
> 3. Change the CharField to a TextField and generate a migration
> 4. Run the migration or inspect the SQL with the `sqlmigrate` manage
> command
> 5. Inspect the database indexes or migration SQL and see that the indexed
> TextField does not have a `_like` index
> 6. Reverse the migration
> 7. Inspect the database indexes or migration SQL and see that the indexed
> CharField no longer has a `_like` index
>
> Here is an example project that demonstratest the issue:
> https://github.com/robin-ray/alter_text_index_repro
New description:
When converting an indexed CharField to a TextField (and vice versa) on
PostgreSQL, Django drops the existing pattern ops `_like` index for the
column but does not recreate it with the new pattern ops. When reversing
the migration, Django does not recreate the initial `_like` index.
I have been able to reproduce this behavior in Django 3.2 and 5.0.
**Reproduction**
1. Given a model with a CharField that has `db_index=True` on a PostgreSQL
database
2. Inspect the database indexes or migration SQL and see that the indexed
CharField has two indexes, one of which ends in `_like` and uses
`varchar_pattern_ops`
3. Change the CharField to a TextField and generate a migration
4. Run the migration or inspect the SQL with the `sqlmigrate` manage
command
5. Inspect the database indexes or migration SQL and see that the indexed
TextField does not have a `_like` index
6. Reverse the migration
7. Inspect the database indexes or migration SQL and see that the indexed
CharField no longer has a `_like` index
Here is an example project that demonstrates the issue: https://github.com
/robin-ray/alter_text_index_repro
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Ticket URL: <https://code.djangoproject.com/ticket/35180#comment:1>
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