Generate separate queries instead of OR filters
#1035
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For the case where we were deleting models with files in chunk, the actual `DELETE` query would be chained to the existing input queryset. That way, the resulting query would have `WHERE original_filter AND id IN (original_filter...)`. Now only the `IN` part should remain. Also adds a bunch of tracing annotations to better see each phase, in particular these file deletions.
In todays episode of "the DB is slow for unexplainable reasons", we found out that querying `compare_commitcomparison` by **both** `base_commit_id` **OR** `compare_commit_id` is horribly slow. It is using a `Seq Scan` in that case for reasons unknown. Splitting that `OR` filter up into two separate queries makes the DB use the appropriate indices, and the queries become instant. We can do this as the `OR` filter pretty much takes the union of both queries, which is equivalent of running both queries separately. God only knows why, but here we are.
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giovanni-guidini
approved these changes
Jan 28, 2025
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In todays episode of "the DB is slow for unexplainable reasons", we found out that querying
compare_commitcomparisonby bothbase_commit_idORcompare_commit_idis horribly slow. It is using aSeq Scanin that case for reasons unknown.Splitting that
ORfilter up into two separate queries makes the DB use the appropriate indices, and the queries become instant. We can do this as theORfilter pretty much takes the union of both queries, which is equivalent of running both queries separately.God only knows why, but here we are.