orca: fall back on replicated CTE only when consumed in 2+ slices#398
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orca: fall back on replicated CTE only when consumed in 2+ slices#398Alena0704 wants to merge 3 commits into
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Alena0704
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July 3, 2026 11:45
Only a replicated CTE consumed in 2+ different slices hangs, not any cross-slice consumer. Narrow the fallback check to that case.
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FHasCrossSliceReplicatedCTEConsumer modeled slice assignment on the ORCA CExpression tree, before DXL/Plan translation.
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…verage A cross-slice ShareInputScan only executes correctly when its producer and consumer gangs run on the same set of segments: the writer on each producing segment waits for an ack from a reader on that same segment (nodeShareInputScan.c). When the two slices cover different segment sets -- e.g. a DISTRIBUTED REPLICATED CTE materialized on all segments but consumed in a single-segment slice under a Gather 1:1 -- a writer waits for an ack that never arrives and the query hangs to statement_timeout. Detect this on the final plan, where per-slice segment coverage is actually known. apply_shareinput_xslice() already walks the plan with a motId stack; carry a parallel stack of each slice's coverage key (SINGLETON segindex, or "all segments", mirroring how FillSliceTable() sizes an ORCA plan's gangs). When a share is marked cross-slice, compare the producer's and consumer's coverage; if they differ (and the share is not a QD share, which pass 4 relocates onto the QD), set a hazard flag. optimize_query() then discards the ORCA plan and lets the Postgres planner plan the query.
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orca: fall back on replicated CTE only when consumed in 2+ slices
Only a replicated CTE consumed in 2+ different slices hangs, not any
cross-slice consumer. Narrow the fallback check to that case