#36475: Optimize F-expression slice to MySQL column-prefix index
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Reporter: JaeHyuckSa | Owner: (none)
Type: | Status: closed
Cleanup/optimization |
Component: Database layer | Version: 5.1
(models, ORM) |
Severity: Normal | Resolution: needsinfo
Keywords: | 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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Changes (by Sarah Boyce):
* resolution: => needsinfo
* status: new => closed
Comment:
Unless I have misunderstood, which is very possible, I don't see how this
can be implemented without a new index class like `PrefixIndex` which was
suggested within #35777 and I see is what you have written for django-
mysql
Slicing an `F` expression of a `CharField` resolves to a `Substr`
expression. The MySQL syntax `col_name(length)` is (from what I can tell)
is index specific and so not we won't be able to override the sql for
MySQL within `Substr`. In the PR discussion you mentioned overriding
`_create_index_sql` but I can't envision what you are thinking. If you
have a draft PR to propose this I might be able to see what you mean?
Note that #16460 is almost a duplicate
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Ticket URL: <https://code.djangoproject.com/ticket/36475#comment:3>
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