Function EvalPlanQualBegin

src/backend/executor/execMain.c:3884–3937

* Initialize or reset an EvalPlanQual state tree */

 * Initialize or reset an EvalPlanQual state tree
 */
void
EvalPlanQualBegin(EPQState *epqstate)
{
	EState	   *parentestate = epqstate->parentestate;
	EState	   *recheckestate = epqstate->recheckestate;

	if (recheckestate == NULL)
	{
		/* First time through, so create a child EState */
		EvalPlanQualStart(epqstate, epqstate->plan);
	}
	else
	{
		/*
		 * We already have a suitable child EPQ tree, so just reset it.
		 */
		Index		rtsize = parentestate->es_range_table_size;
		PlanState  *rcplanstate = epqstate->recheckplanstate;

		MemSet(epqstate->relsubs_done, 0, rtsize * sizeof(bool));

		/* Recopy current values of parent parameters */
		if (parentestate->es_plannedstmt->paramExecTypes != NIL)
		{
			int			i;

			/*
			 * Force evaluation of any InitPlan outputs that could be needed
			 * by the subplan, just in case they got reset since
			 * EvalPlanQualStart (see comments therein).
			 */
			ExecSetParamPlanMulti(rcplanstate->plan->extParam,
								  GetPerTupleExprContext(parentestate), NULL);

			i = list_length(parentestate->es_plannedstmt->paramExecTypes);

			while (--i >= 0)
			{
				/* copy value if any, but not execPlan link */
				recheckestate->es_param_exec_vals[i].value =
					parentestate->es_param_exec_vals[i].value;
				recheckestate->es_param_exec_vals[i].isnull =
					parentestate->es_param_exec_vals[i].isnull;
			}
		}

		/*
		 * Mark child plan tree as needing rescan at all scan nodes.  The
		 * first ExecProcNode will take care of actually doing the rescan.
		 */
		rcplanstate->chgParam = bms_add_member(rcplanstate->chgParam,
											   epqstate->epqParam);
	}
}

/*
 * Start execution of an EvalPlanQual plan tree.