fix: LazyMemoryExec should produce independent streams per execute()#21565
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viirya wants to merge 1 commit intoapache:mainfrom
Open
fix: LazyMemoryExec should produce independent streams per execute()#21565viirya wants to merge 1 commit intoapache:mainfrom
viirya wants to merge 1 commit intoapache:mainfrom
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LazyMemoryExec::execute() was sharing the same generator instance (via Arc::clone) across multiple calls, causing streams to share mutable state. This meant a second call to execute(0) would continue from where the first call left off, instead of starting from the beginning. Fix by calling reset_state() on the generator to create a fresh instance for each execute() call, matching the expected ExecutionPlan semantics that each execute() produces an independent stream. Co-authored-by: Isaac
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Which issue does this PR close?
Rationale for this change
LazyMemoryExec::execute() shares the same generator instance across multiple calls via Arc::clone, so a second call to execute(0) continues from where the first left off instead of starting from the beginning. This is inconsistent with how other ExecutionPlan implementations behave, where each execute() call produces an independent stream. This was discovered while writing e2e tests for NestedLoopJoinExec memory-limited execution (#21448), where the OOM fallback path re-executes the left child plan and got incomplete results.
What changes are included in this PR?
LazyMemoryExec::execute() was sharing the same generator instance (via Arc::clone) across multiple calls, causing streams to share mutable state. This meant a second call to execute(0) would continue from where the first call left off, instead of starting from the beginning.
Fix by calling reset_state() on the generator to create a fresh instance for each execute() call, matching the expected ExecutionPlan semantics that each execute() produces an independent stream.
Are these changes tested?
Unit test
Are there any user-facing changes?
No