perf(v_ahb_diff): replace NOT EXISTS with LEFT JOIN for better query performance#225
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perf(v_ahb_diff): replace NOT EXISTS with LEFT JOIN for better query performance#225
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…performance The v_ahb_diff view used NOT EXISTS subqueries to detect added and deleted rows. These correlated subqueries execute once per row, which can be slow especially when SQLite cannot optimize the subquery efficiently. This change replaces the two NOT EXISTS patterns with LEFT JOIN + IS NULL: - Added rows: LEFT JOIN old version, WHERE old.id_path IS NULL - Deleted rows: LEFT JOIN new version, WHERE new.id_path IS NULL LEFT JOIN allows SQLite to use index lookups directly during the join phase rather than running a separate subquery for each candidate row. This is a well-known SQL optimization pattern that typically performs better across database engines. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
hf-krechan
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Dec 16, 2025
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Pull request overview
This PR optimizes the v_ahb_diff view by replacing correlated NOT EXISTS subqueries with LEFT JOIN + IS NULL patterns for better query performance in SQLite. The view compares AHB versions to detect added, deleted, modified, and unchanged rows.
Key Changes:
- Replaced
NOT EXISTSwithLEFT JOINfor detecting added rows (rows in new version but not in old) - Replaced
NOT EXISTSwithLEFT JOINfor detecting deleted rows (rows in old version but not in new)
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…performance
The v_ahb_diff view used NOT EXISTS subqueries to detect added and deleted rows. These correlated subqueries execute once per row, which can be slow especially when SQLite cannot optimize the subquery efficiently.
This change replaces the two NOT EXISTS patterns with LEFT JOIN + IS NULL:
LEFT JOIN allows SQLite to use index lookups directly during the join phase rather than running a separate subquery for each candidate row. This is a well-known SQL optimization pattern that typically performs better across database engines.
🤖 Generated with Claude Code