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fix: compact FIRST_VALUE scalars during merge - #26743
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shehabgamin wants to merge 2 commits into
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shehabgamin wants to merge 2 commits into
shehabgamin wants to merge 2 commits into
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shehabgamin
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FIRST_VALUE scalars during merge
kumarUjjawal
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Oct 25, 2026
kumarUjjawal
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Thank you @shehabgamin
Looks good 👍
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Thanks @shehabgamin and @kumarUjjawal Is there any way we can get a .slt / sql end user API repro for this? |
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The reproducer in #26744 (comment) is probably a good start |
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Which issue does this PR close?
Closes #26744.
Rationale for this change
DISTINCT ONqueries carrying nested payloads can fail with a memory reservation error during aggregate spill/replay because mergedFIRST_VALUEstates retain backing buffers from larger arrays.What changes are included in this PR?
Call
self.first.compact()after extracting the selected scalar inTrivialFirstValueAccumulator::merge_batch, matching the existing behavior inupdate_batch.What is the testing strategy for this PR?
Locally validated against unpatched and patched DataFusion 55.2.0. An accumulator regression check confirms that merging a list state preserves its value and reports the same memory size as updating it directly; it fails before the fix and passes afterward.
The spill workload described in #26744 fails before the fix and returns all 8,192 rows with correct nested payloads afterward, while still exercising spilling.
Are there any user-facing changes?
No.