Opened 11 years ago

Closed 7 years ago

#8769 closed Cleanup/optimization (fixed)

Slightly over-aggressive join promotion in SQL for ordering

Reported by: Malcolm Tredinnick Owned by: Malcolm Tredinnick
Component: Database layer (models, ORM) Version: master
Severity: Normal Keywords:
Cc: Triage Stage: Accepted
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no


Right now, we promote any table join used in the ordering portion to an outer join if it potentially contains NULL values (the corresponding Django field has null=True). There are some cases where this is unnecessary. If we already used that join in the filter statements and didn't make it an outer join at that point, it's because we are already filtering out the null values, so an inner join still won't lose any results in the ordering.

Thus, we should only promote joins for ordering if we needed to add that join for the ordering (this means self.alias_refcount[...] == 1, or something else that's easily detectable).

Noting this so I don't forget. Don't want to introduce new bugs at the moment and it's a bit of an edge case, so it can wait until post-1.0.

Change History (5)

comment:1 Changed 11 years ago by Malcolm Tredinnick

Status: newassigned
Triage Stage: UnreviewedAccepted

comment:2 Changed 8 years ago by Luke Plant

Severity: Normal
Type: Cleanup/optimization

comment:3 Changed 7 years ago by Aymeric Augustin

UI/UX: unset

Change UI/UX from NULL to False.

comment:4 Changed 7 years ago by Aymeric Augustin

Easy pickings: unset

Change Easy pickings from NULL to False.

comment:5 Changed 7 years ago by Anssi Kääriäinen

Resolution: fixed
Status: assignedclosed

This one seems to be fixed in: 8c72aa237918e31a525022f72b22cac75451af86

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