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Allow parallel custom and foreign scans.

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This patch doesn't put the new infrastructure to use anywhere, and
indeed it's not clear how it could ever be used for something like
postgres_fdw which has to send an SQL query and wait for a reply,
but there might be FDWs or custom scan providers that are CPU-bound,
so let's give them a way to join club parallel.

KaiGai Kohei, reviewed by me.
This commit is contained in:
Robert Haas
2016-02-03 12:46:18 -05:00
parent 25e44518c1
commit 69d34408e5
9 changed files with 263 additions and 1 deletions
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62
src/backend/executor/nodeForeignscan.c
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@ -282,3 +282,65 @@ ExecReScanForeignScan(ForeignScanState *node)
ExecScanReScan(&node->ss);
}
/* ----------------------------------------------------------------
* ExecForeignScanEstimate
*
* Informs size of the parallel coordination information, if any
* ----------------------------------------------------------------
*/
void
ExecForeignScanEstimate(ForeignScanState *node, ParallelContext *pcxt)
{
FdwRoutine *fdwroutine = node->fdwroutine;
if (fdwroutine->EstimateDSMForeignScan)
{
node->pscan_len = fdwroutine->EstimateDSMForeignScan(node, pcxt);
shm_toc_estimate_chunk(&pcxt->estimator, node->pscan_len);
shm_toc_estimate_keys(&pcxt->estimator, 1);
}
}
/* ----------------------------------------------------------------
* ExecForeignScanInitializeDSM
*
* Initialize the parallel coordination information
* ----------------------------------------------------------------
*/
void
ExecForeignScanInitializeDSM(ForeignScanState *node, ParallelContext *pcxt)
{
FdwRoutine *fdwroutine = node->fdwroutine;
if (fdwroutine->InitializeDSMForeignScan)
{
int plan_node_id = node->ss.ps.plan->plan_node_id;
void *coordinate;
coordinate = shm_toc_allocate(pcxt->toc, node->pscan_len);
fdwroutine->InitializeDSMForeignScan(node, pcxt, coordinate);
shm_toc_insert(pcxt->toc, plan_node_id, coordinate);
}
}
/* ----------------------------------------------------------------
* ExecForeignScanInitializeDSM
*
* Initialization according to the parallel coordination information
* ----------------------------------------------------------------
*/
void
ExecForeignScanInitializeWorker(ForeignScanState *node, shm_toc *toc)
{
FdwRoutine *fdwroutine = node->fdwroutine;
if (fdwroutine->InitializeWorkerForeignScan)
{
int plan_node_id = node->ss.ps.plan->plan_node_id;
void *coordinate;
coordinate = shm_toc_lookup(toc, plan_node_id);
fdwroutine->InitializeWorkerForeignScan(node, toc, coordinate);
}
}