#36571: Deprecated usage of BINARY expr in MySQL lookups
-------------------------------------+-------------------------------------
Reporter: Simon Charette | Owner: (none)
Type: | Status: new
Cleanup/optimization |
Component: Database layer | Version: 5.2
(models, ORM) |
Severity: Normal | Resolution:
Keywords: mysql binary like | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Simon Charette):
> Would `CAST(... AS BINARY)` be enough here? This only casts the pattern
and not the column?
I think you're right, we'd need to cast both the left and right hand side
of the operator.
> That might lead to subtle differences depending on the column's
collation or affect index usage. Would `COLLATE ..._bin` be closer to the
old `LIKE BINARY`, since it applies a binary collation to the column and
the pattern?
The problem with that is that it requires knowing the right-hand-side's
collation at query execution time and append the `..._bin` suffix to it.
I guess we could use `rhs.output_field.db_collation` and default to
`utf8mb_bin` if missing but that could also subtly break as there could be
databases out there with collations that are not matching the Django model
representation of it and were working fine previously when using `LIKE
BINARY`.
This whole thing makes me wonder why they deprecated this option in the
first place as it seems quite handy.
--
Ticket URL: <https://code.djangoproject.com/ticket/36571#comment:2>
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