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Teach bitmap heap scan to cope with absence of a DSA.

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If we have a plan that uses parallelism but are unable to execute it
using parallelism, for example due to a lack of available DSM
segments, then the EState's es_query_dsa will be NULL.  Parallel
bitmap heap scan needs to fall back to a non-parallel scan in such
cases.

Patch by me, reviewed by Dilip Kumar

Discussion: http://postgr.es/m/CAEepm=0kADK5inNf_KuemjX=HQ=PuTP0DykM--fO5jS5ePVFEA@mail.gmail.com
This commit is contained in:
Robert Haas 2017-11-28 11:39:16 -05:00
parent 7015bb3894
commit ec7629dfb9
1 changed files with 11 additions and 0 deletions
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11
src/backend/executor/nodeBitmapHeapscan.c
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@ -963,6 +963,11 @@ ExecBitmapHeapInitializeDSM(BitmapHeapScanState *node,
{
ParallelBitmapHeapState *pstate;
EState *estate = node->ss.ps.state;
dsa_area *dsa = node->ss.ps.state->es_query_dsa;
/* If there's no DSA, there are no workers; initialize nothing. */
if (dsa == NULL)
return;
pstate = shm_toc_allocate(pcxt->toc, node->pscan_len);
@ -995,6 +1000,10 @@ ExecBitmapHeapReInitializeDSM(BitmapHeapScanState *node,
ParallelBitmapHeapState *pstate = node->pstate;
dsa_area *dsa = node->ss.ps.state->es_query_dsa;
/* If there's no DSA, there are no workers; do nothing. */
if (dsa == NULL)
return;
pstate->state = BM_INITIAL;
if (DsaPointerIsValid(pstate->tbmiterator))
@ -1019,6 +1028,8 @@ ExecBitmapHeapInitializeWorker(BitmapHeapScanState *node, shm_toc *toc)
ParallelBitmapHeapState *pstate;
Snapshot snapshot;
Assert(node->ss.ps.state->es_query_dsa != NULL);
pstate = shm_toc_lookup(toc, node->ss.ps.plan->plan_node_id, false);
node->pstate = pstate;