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Rewrite get_user_purchases has_new_version subquery Replace double-nested correlated EXISTS/NOT EXISTS with two LATERAL COUNT joins (total versions with s3_key vs downloaded count). The old pattern scanned the versions table per-row per-purchase; the new pattern counts once per item. Improves library page query performance as users accumulate purchases.
Co-Authored-By
Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Author: Max J. <87768334+MaxJMath@users.noreply.github.com> · 2026-05-09 03:09 UTC
Commit: a81254d72b319def3d95817f526ff1c96b665e1a
Parent: fed8192
2 files changed, +12 insertions, -9 deletions
M server/docs/todo.md +1 -1
@@ -43,7 +43,7 @@
43 43 - [x] Fix XSS: escape `s.category` and `s.url` in search suggestions innerHTML (discover.html)
44 44 - [x] Fix XSS: replace inline `onsubmit` handler with `addEventListener` in collections.js
45 45 - [x] Fix a11y: convert `<span onclick>` save buttons to `<button>` with `aria-label` on discover cards
46 - - [ ] Performance: consider rewriting double-nested correlated subquery in `get_user_purchases` (has_new_version) to use LEFT JOIN or CTE
46 + - [x] Performance: rewrite `get_user_purchases` double-nested correlated subquery — replaced with LATERAL joins counting total versions vs downloaded versions
47 47 - [x] Remove unused import `spawn_email` in `stripe/checkout/cart.rs`
48 48 - [x] Remove dead code `update_app_sync_sub_tier` in `db/app_sync.rs`
49 49
M server/src/db/transactions.rs +11 -8
@@ -505,19 +505,22 @@
505 505 p.purchased_at,
506 506 (i.price_cents = 0) as is_free,
507 507 lk.key_code as license_key_code,
508 - EXISTS (
509 - SELECT 1 FROM versions v
510 - WHERE v.item_id = i.id AND v.s3_key IS NOT NULL
511 - AND NOT EXISTS (
512 - SELECT 1 FROM user_downloads ud
513 - WHERE ud.user_id = p.buyer_id AND ud.version_id = v.id
514 - )
515 - ) as has_new_version
508 + (vc.total_versions > 0 AND vc.total_versions > COALESCE(dc.downloaded_count, 0)) as has_new_version
516 509 FROM purchases p
517 510 JOIN items i ON p.item_id = i.id
518 511 JOIN projects proj ON i.project_id = proj.id
519 512 JOIN users u ON proj.user_id = u.id
520 513 LEFT JOIN license_keys lk ON lk.item_id = p.item_id AND lk.owner_id = p.buyer_id AND lk.revoked_at IS NULL
514 + LEFT JOIN LATERAL (
515 + SELECT COUNT(*) AS total_versions
516 + FROM versions v
517 + WHERE v.item_id = i.id AND v.s3_key IS NOT NULL
518 + ) vc ON true
519 + LEFT JOIN LATERAL (
520 + SELECT COUNT(*) AS downloaded_count
521 + FROM user_downloads ud
522 + WHERE ud.user_id = p.buyer_id AND ud.item_id = i.id
523 + ) dc ON true
521 524 WHERE p.buyer_id = $1
522 525 ORDER BY p.item_id, p.purchased_at DESC
523 526 ) deduped