Function ExecInitSubqueryScan

src/backend/executor/nodeSubqueryscan.c:98–161

---------------------------------------------------------------- * ExecInitSubqueryScan * ---------------------------------------------------------------- */

 * ----------------------------------------------------------------
 */
SubqueryScanState *
ExecInitSubqueryScan(SubqueryScan *node, EState *estate, int eflags)
{
	SubqueryScanState *subquerystate;

	/* check for unsupported flags */
	Assert(!(eflags & EXEC_FLAG_MARK));

	/* SubqueryScan should not have any "normal" children */
	Assert(outerPlan(node) == NULL);
	Assert(innerPlan(node) == NULL);

	/*
	 * create state structure
	 */
	subquerystate = makeNode(SubqueryScanState);
	subquerystate->ss.ps.plan = (Plan *) node;
	subquerystate->ss.ps.state = estate;
	subquerystate->ss.ps.ExecProcNode = ExecSubqueryScan;

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &subquerystate->ss.ps);

	/*
	 * initialize subquery
	 */
	subquerystate->subplan = ExecInitNode(node->subplan, estate, eflags);

	/*
	 * Initialize scan slot and type (needed by ExecAssignScanProjectionInfo)
	 */
	ExecInitScanTupleSlot(estate, &subquerystate->ss,
						  ExecGetResultType(subquerystate->subplan),
						  ExecGetResultSlotOps(subquerystate->subplan, NULL));

	/*
	 * The slot used as the scantuple isn't the slot above (outside of EPQ),
	 * but the one from the node below.
	 */
	subquerystate->ss.ps.scanopsset = true;
	subquerystate->ss.ps.scanops = ExecGetResultSlotOps(subquerystate->subplan,
														&subquerystate->ss.ps.scanopsfixed);
	subquerystate->ss.ps.resultopsset = true;
	subquerystate->ss.ps.resultops = subquerystate->ss.ps.scanops;
	subquerystate->ss.ps.resultopsfixed = subquerystate->ss.ps.scanopsfixed;

	/*
	 * Initialize result type and projection.
	 */
	ExecInitResultTypeTL(&subquerystate->ss.ps);
	ExecAssignScanProjectionInfo(&subquerystate->ss);

	/*
	 * initialize child expressions