[dongwonmoon]

Summary

Implement the correlated EXISTS proposed in #4526 for PostgreSQL session activity queries.

The existing hasData expression checks event IDs against site/date-wide event_data. Depending on the data and query plan, opening a session profile can repeatedly scan a large materialized result. The correlated check lets PostgreSQL look up properties for each event using the existing website_event_id index.

Website/date predicates, returned fields, ordering, and the 500-row limit are unchanged. No new index or configuration is required. The ClickHouse implementation is unchanged.

Verification

• Compared all returned fields for 500 rows on synthetic PostgreSQL 15.19 data; the results matched.
• Ran a small source-derived SQL check covering date boundaries, NULL dates, other-site data, multiple sessions, missing qualifying properties, multiple properties, and performance-event exclusion.
• Build passed with SKIP_DB_CHECK=1 (database checks/migrations skipped).
• Three related unit tests passed; the changed file passes lint.
• Full lint fails on existing diagnostics: the unmodified and patched versions of the same dev revision produce identical diagnostics (6 errors, 13 warnings, 11 infos).

These are SQL-level checks using temporary tables, not a production or API performance benchmark. The diagnosis and proposed approach come from #4526; this change implements that approach with independent verification.

Source-derived SQL check · Measurement summary and limitations

Related: #4526

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[greptile-apps]

Greptile Summary

This PR optimizes PostgreSQL session activity queries by replacing a website/date-wide IN subquery with a correlated EXISTS lookup.

• Preserves the existing website and date constraints used to calculate hasData.
• Correlates each event directly through event_data.website_event_id.
• Leaves returned fields, ordering, row limits, and the ClickHouse implementation unchanged.

Confidence Score: 5/5

The PR appears safe to merge with no actionable correctness, security, or repository-rule issues identified.

The changed predicate preserves the prior filtering semantics while correlating through a non-null indexed foreign key, and no concrete regression remains.

Important Files Changed

Filename	Overview
src/queries/sql/sessions/getSessionActivity.ts	Rewrites the PostgreSQL hasData predicate as a semantically equivalent correlated lookup that can use the existing event ID index.

_{Reviews (1): Last reviewed commit: "Use correlated EXISTS for PostgreSQL ses..." | Re-trigger Greptile}