perf(postgresql): replace correlated NOT EXISTS with set-based EXCEPT in prune_stale_cooccurrences (#2660)#2797
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… in prune_stale_cooccurrences The original Pass-3 correlated NOT EXISTS self-join evaluates per-row against unit_entities, hitting a 300s statement_timeout on large graphs (50K+ entities, 1M+ unit_entities). The set-based EXCEPT rewrite materializes the stale cooccurrence set once and deletes against it — same result, ~90x faster (~3.4s vs 300s for 5.7K stale rows). Closes vectorize-io#2660
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Summary
The original Pass-3
prune_stale_cooccurrencesuses a correlatedNOT EXISTSself-join onunit_entitiesthat evaluates per-row. On large graphs:unit_entitiesrowsentity_cooccurrencesrowsThis hits a 300s
statement_timeoutwith 0 rows pruned because Postgres can't complete the per-row evaluation in time.Changes
Replaced the correlated
NOT EXISTSwith a set-basedEXCEPT:cooccurrences EXCEPT valid_witness_pairsThis produces the identical result set (verified via bidirectional
EXCEPTand ordered digest match) while completing in ~3.4s vs >300s for the correlated form — ~90x faster.Verification
OLD EXCEPT NEW = 0,NEW EXCEPT OLD = 0Closes #2660