Function ExecSeqScanInitializeDSM

src/backend/executor/nodeSeqscan.c:328–359

---------------------------------------------------------------- * ExecSeqScanInitializeDSM * * Set up a parallel heap scan descriptor. * ---------------------------------------------------------------- */

 * ----------------------------------------------------------------
 */
void
ExecSeqScanInitializeDSM(SeqScanState *node,
						 ParallelContext *pcxt)
{
	EState	   *estate = node->ss.ps.state;
	ParallelTableScanDesc pscan;
	TableScanDesc scandesc;

	pscan = shm_toc_allocate(pcxt->toc, node->pscan_len);

	Assert(pscan);

	table_parallelscan_initialize(node->ss.ss_currentRelation,
								  pscan,
								  estate->es_snapshot);
	shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, pscan);
	if (node->ss.ss_currentRelation->rd_tableam->scan_begin_extractcolumns)
	{
		/* try parallel mode for AOCO extract columns */
		scandesc = table_beginscan_es(node->ss.ss_currentRelation,
									  estate->es_snapshot,
									  0, NULL,
									  pscan,
									  &node->ss.ps);
	}
	else
	{
		/* normal parallel mode */
		scandesc = table_beginscan_parallel(node->ss.ss_currentRelation, pscan);
	}
	node->ss.ss_currentScanDesc = scandesc;
}

/* ----------------------------------------------------------------
 *		ExecSeqScanReInitializeDSM