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Fix: disable parallel index build on QD and AO tables (#12) #15

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Merged
my-ship-it merged 1 commit into from
Jul 16, 2026
Merged

Fix: disable parallel index build on QD and AO tables (#12) #15

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10 changes: 10 additions & 0 deletions src/hnswbuild.c
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,7 @@
#include "access/xloginsert.h"
#include "catalog/index.h"
#include "catalog/pg_type_d.h"
#include "cdb/cdbvars.h"
#include "commands/progress.h"
#include "hnsw.h"
#include "miscadmin.h"
Expand Down Expand Up @@ -1037,6 +1038,15 @@ ComputeParallelWorkers(Relation heap, Relation index)
{
int parallel_workers;

/*
* Follow index_build(): parallel workers launched on the QD inherit
* QE-only interconnect state (ic_htab_size, numsegmentsFromQD) that is
* unset in a dispatcher backend, so disable parallelism on the QD and
* for AO tables just like the core btree build path does.
*/
if (Gp_role == GP_ROLE_DISPATCH || AMHandlerIsAO(heap->rd_amhandler))
return 0;

/* Make sure it's safe to use parallel workers */
parallel_workers = plan_create_index_workers(RelationGetRelid(heap), RelationGetRelid(index));
if (parallel_workers == 0)
Expand Down
10 changes: 8 additions & 2 deletions src/ivfbuild.c
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Expand Up @@ -934,8 +934,14 @@ AssignTuples(IvfflatBuildState * buildstate)

pgstat_progress_update_param(PROGRESS_CREATEIDX_SUBPHASE, PROGRESS_IVFFLAT_PHASE_ASSIGN);

/* Calculate parallel workers */
if (buildstate->heap != NULL)
/*
* Follow index_build(): parallel workers launched on the QD inherit
* QE-only interconnect state (ic_htab_size, numsegmentsFromQD) that is
* unset in a dispatcher backend, so disable parallelism on the QD and
* for AO tables just like the core btree build path does.
*/
if (buildstate->heap != NULL && Gp_role != GP_ROLE_DISPATCH &&
!AMHandlerIsAO(buildstate->heap->rd_amhandler))
parallel_workers = plan_create_index_workers(RelationGetRelid(buildstate->heap), RelationGetRelid(buildstate->index));

/* Attempt to launch parallel worker scan when required */
Expand Down
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