#29692: Incorrect removal of order_by clause created as multiline RawSQL
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Reporter: Marcin Nowak | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.11
(models, ORM) |
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
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Comment (by Marcin Nowak):
> Is there a reason you can't use ​conditional expressions
No, but I didn't knew about the issue, and writing raw sqls is sometimes
faster (not in this case ;)
I'm really happy having possibility to mix raw sqls with object queries.
Next time I'll use expressions, for sure.
> Allowing the ordering optimization stuff to handle arbitrary RawSQL may
be difficult.
Personally I'd like to skip RawSQL clauses in the block which is
responsible for finding duplicates. If someone is using raw sqls, he knows
the best what he is doing, IMO. And it is quite strange if Django removes
silently part of your SQL. This is very confusing. And please note that
printing a `Query` instance was generating incomplete sql, but while
checking `Query.order_by` manually, the return value was containing all
clauses. I thought that just printing is affected, but our QA dept told me
the truth ;)
I know there is no effective way to compare similarity of two raw clauses.
This may be hard for expression objects, too, but you have a possibility
to implement some `__eq__` magic (instead of comparation of generated
sqls). Unfortunately I don't know why duplicates detection was
implemented, so it's hard to tell how to improve this part.
--
Ticket URL: <https://code.djangoproject.com/ticket/29692#comment:2>
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