Include OFFSET in physical optimizer group-trim limit pushdown#18600
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yashmayya merged 1 commit intoMay 28, 2026
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The group-trim rule pushed limit=fetch and dropped the offset, so paginated DISTINCT/GROUP BY queries on the physical optimizer (usePhysicalOptimizer=true) came back short. Push offset+fetch instead so the leaf/final aggregate keeps enough groups to cover the OFFSET window. The legacy path is unaffected since its sort-exchange-copy rule already folds the offset before the aggregate rule. Fixes apache#18592
yashmayya
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Additional details and impacted files@@ Coverage Diff @@
## master #18600 +/- ##
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- Coverage 64.31% 64.26% -0.05%
Complexity 1137 1137
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Files 3335 3335
Lines 205710 206046 +336
Branches 32085 32142 +57
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+ Hits 132295 132415 +120
- Misses 62774 62976 +202
- Partials 10641 10655 +14
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Jackie-Jiang
approved these changes
May 27, 2026
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On the physical optimizer path (
usePhysicalOptimizer=true), the group-trim rule pushedlimit = fetchinto the leaf/final aggregate and ignored the queryOFFSET. PaginatedDISTINCT/GROUP BYqueries that hit group trim then trimmed away rows the outerOFFSET ... FETCHwindow still needed and came back short — silently wrong results, no error. It now pushesoffset + fetch(clamped to avoid int overflow) so the leaf/final aggregate keeps enough groups.The default/legacy planner isn't affected: its sort-exchange-copy rule already folds the offset into the inner sort's fetch before the aggregate rule runs, so that rule sees
offset + fetchthere.PINOT_POST_RULES_V2has no sort-exchange rule, soPinotLogicalAggregateRulematches the raw outer sort and has to add the offset itself.Tests
PhysicalOptimizerPlans.json): no-aggregateDISTINCT ... LIMIT n OFFSET mand hinted aggregate, asserting leaf/finallimit=[offset+fetch].GroupByOptionsTest,usePhysicalOptimizer=true): paginated DISTINCT and hinted-aggregate paths return a full page. Verified it fails (0 rows) without the fix.Fixes #18592