#16187: Refactor lookup system
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Reporter: UloPe | Owner: akaariai
Type: | Status: assigned
Cleanup/optimization | Version: master
Component: Database layer | Resolution:
(models, ORM) | Triage Stage: Accepted
Severity: Normal | Needs documentation: 0
Keywords: | Patch needs improvement: 1
Has patch: 1 | UI/UX: 0
Needs tests: 0 |
Easy pickings: 0 |
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Comment (by akaariai):
Just take simple queries and see how they are built and executed by the
ORM.
Try to pick one area to concentrate at a time. For the lookup refactor
checking where clause entries generation and execution is naturally
important. The basic path for generating a clause is qs.filter() ->
_filter_or_exclude() -> query.add_q() -> query._add_q() ->
query.build_filter() -> query.setup_joins(). At execution time the
query.where clause is converted to SQL by WhereNode.as_sql() (and
WhereNode.make_atom() as part of that).
Try to ignore HAVING clause generation at start. If you wonder why
something is needed, change it and run queries tests - that test module
alone covers most of ORM features. The broken tests should tell you why
any particular part is needed.
--
Ticket URL: <https://code.djangoproject.com/ticket/16187#comment:31>
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