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Let a paged numeric range stop at the page instead of sorting every match - #2920
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Three apps sync with the same query: a numeric range on one attribute,
ordered by it, 500 rows at a time with a cursor:
{:prices {:$ {:where {:and [{:modified {:$gt a}} {:modified {:$lte b}}]}
:order {:modified "asc"} :first 500 :after cursor}}}
Each page scans every row above the lower bound, looks each one up twice
more, sorts them all, and keeps 500. In prod that was one statement at
14.6% of all shared buffer hits.
The filters, the order, and the cursor all read the same single-valued
attribute, so t0, t1 and t2 are the same triple. For apps enabled in the
new scoped-query-plans flag (plan numeric-range-page):
- the first scan also gets the upper bound
- the page and the previous-page check order by the first scan's
columns, so the planner keeps the index order and the limit stops the
scan early
- for a required attribute, the page also bounds the first scan with the
cursor value
- the child join reuses the page's entity ids, as it already does for
one other app
Read-only in prod with real parameters, inside one repeatable-read
snapshot: 223,024 buffer hits and 197 ms before, 14,141 hits after. The
500 page rows are identical and in the same order, has-next and
has-previous match, and the 3,000 child triples match as a multiset.
disable-scoped-query-plans and disable-pg-hints turn it off.
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Included review availability: Your plan provides up to 10 included reviews per hour; 8 remain after this review. 📝 WalkthroughWalkthroughThe change adds feature-gated numeric range pagination planning. Matching queries receive specialized scans, ordering, cursor handling, and previous-page behavior. Tests cover activation, compiled SQL, unsupported shapes, and duplicate-free pagination results. ChangesNumeric range pagination
Priority: ➖ Normal Estimated code review effort: 4 (Complex) | ~45 minutes Change: Feature Sequence Diagram(s)sequenceDiagram
participant QueryCompiler
participant scoped_query_plans
participant PostgreSQL
QueryCompiler->>scoped_query_plans: compile an enabled numeric range page query
scoped_query_plans->>scoped_query_plans: apply bounds, ordering, and cursor handling
scoped_query_plans-->>QueryCompiler: return the modified plan
QueryCompiler->>PostgreSQL: execute the compiled SQL
Merge Risk: ⚪ Minimal · up to This change adds an optional, flag-gated fast path for a specific numeric-range pagination shape, with two independent kill switches and a fallback to the existing, already-correct query path whenever the specialized shape or deeper validation does not match. Investigation of the flag combination and of the child-result-reuse logic did not surface a scenario that returns incorrect or incomplete data, so the change appears safe to merge with normal monitoring of the new fast path's behavior in production. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
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Inline comments:
In `@server/src/instant/db/scoped_query_plans.clj`:
- Around line 366-385: Update apply-plan so numeric-range-page runs as a
fallback after the app-specific case branch, including when a matching planner
returns nil. Wrap the case result in or, make the case default nil, and invoke
numeric-range-page as the fallback while preserving the existing pg-hints guard
and app-specific planner behavior.
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server/src/instant/db/scoped_query_plans.cljserver/src/instant/flags.cljserver/test/instant/db/numeric_range_page_plan_test.clj
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Prod results, 2026-09-17. Deployed 17:41 UTC and enabled through
No query errors for these apps in the hour after enabling. |
1 participant
After the write-side fixes, reads are about 90% of the database's non-IO time. The single largest statement is a sync query that three apps share (a15fca0e, f5d067f2, 26f1cf25): a numeric range on one attribute, ordered by that attribute, 500 rows per page with a cursor.
{:prices {:$ {:where {:and [{:modified {:$gt a}} {:modified {:$lte b}}]} :order {:modified "asc"} :first 500 :after cursor}}}Each page scans every row above the lower bound, looks each row up twice more (
t1,t2), sorts all of them, and keeps 500. Over 8.6 hours on 2026-09-17 that one statement was 14.6% of all shared buffer hits and 6.6% of non-IO execution time, at 1.5 calls per second.The filters, the order, and the cursor all read the same single-valued attribute, so
t0,t1andt2are the same triple. For apps enabled in a newscoped-query-plansflag (plan namenumeric-range-page), the plan:numeric-rangeplan does for one apptriples_number_type_idxorder and the limit stops the scan early (incremental sort on the entity id for ties)m-0is shared with the previous-page check, so its definition does not get the cursor bound.reuse-bound-child-entities?already does for one other appRead-only in prod with real parameters, both queries inside one repeatable-read snapshot:
The 500 page rows are identical and in the same order,
has-nextandhas-previousmatch, and the 3,000 child triples match as a multiset (their order changes, the same as the existing child-entity reuse).Flag shape, same as
scoped-write-plans:{"a15fca0e-3517-40ba-b286-774ae9a46c22": {"numeric-range-page": true}}disable-scoped-query-plansanddisable-pg-hintsturn it off. The plan only applies when the scans, CTE layout, predicates and attribute (cardinality one, checked number) match; anything else keeps the normal SQL.Validation: the new
numeric-range-page-plan-testchecks the rewritten CTEs, the gates, nearby shapes that must not change, and pages through real Postgres data with ties across page boundaries, empty and inverted ranges, comparing every page and its page info with the plan on and off. It passes together with the existing scoped plan tests (37 tests, 369 assertions) andinstaql-testplusdatalog-test(72 tests, 593 assertions). CI clj-kondo config is clean.🤖 Generated with Claude Code