Function ExecParallelInitializeDSM

src/backend/executor/execParallel.c:441–532

* Initialize the dynamic shared memory segment that will be used to control * parallel execution. */

 * parallel execution.
 */
static bool
ExecParallelInitializeDSM(PlanState *planstate,
						  ExecParallelInitializeDSMContext *d)
{
	if (planstate == NULL)
		return false;

	/* If instrumentation is enabled, initialize slot for this node. */
	if (d->instrumentation != NULL)
		d->instrumentation->plan_node_id[d->nnodes] =
			planstate->plan->plan_node_id;

	/* Count this node. */
	d->nnodes++;

	/*
	 * Call initializers for DSM-using plan nodes.
	 *
	 * Most plan nodes won't do anything here, but plan nodes that allocated
	 * DSM may need to initialize shared state in the DSM before parallel
	 * workers are launched.  They can allocate the space they previously
	 * estimated using shm_toc_allocate, and add the keys they previously
	 * estimated using shm_toc_insert, in each case targeting pcxt->toc.
	 */
	switch (nodeTag(planstate))
	{
		case T_SeqScanState:
			if (planstate->plan->parallel_aware)
				ExecSeqScanInitializeDSM((SeqScanState *) planstate,
										 d->pcxt);
			break;
		case T_IndexScanState:
			if (planstate->plan->parallel_aware)
				ExecIndexScanInitializeDSM((IndexScanState *) planstate,
										   d->pcxt);
			break;
		case T_IndexOnlyScanState:
			if (planstate->plan->parallel_aware)
				ExecIndexOnlyScanInitializeDSM((IndexOnlyScanState *) planstate,
											   d->pcxt);
			break;
		case T_ForeignScanState:
			if (planstate->plan->parallel_aware)
				ExecForeignScanInitializeDSM((ForeignScanState *) planstate,
											 d->pcxt);
			break;
		case T_AppendState:
			if (planstate->plan->parallel_aware)
				ExecAppendInitializeDSM((AppendState *) planstate,
										d->pcxt);
			break;
		case T_CustomScanState:
			if (planstate->plan->parallel_aware)
				ExecCustomScanInitializeDSM((CustomScanState *) planstate,
											d->pcxt);
			break;
		case T_BitmapHeapScanState:
			if (planstate->plan->parallel_aware)