Function ExecInitShareInputScan

src/backend/executor/nodeShareInputScan.c:406–516

------------------------------------------------------------------ * ExecInitShareInputScan * ------------------------------------------------------------------ */

 * ------------------------------------------------------------------
 */
ShareInputScanState *
ExecInitShareInputScan(ShareInputScan *node, EState *estate, int eflags)
{
	ShareInputScanState *sisstate;
	Plan	   *outerPlan;
	PlanState  *childState;

	Assert(innerPlan(node) == NULL);

	/* create state data structure */
	sisstate = makeNode(ShareInputScanState);
	sisstate->ss.ps.plan = (Plan *) node;
	sisstate->ss.ps.state = estate;
	sisstate->ss.ps.ExecProcNode = ExecShareInputScan;

	sisstate->ts_state = NULL;
	sisstate->ts_pos = -1;

	/*
	 * init child node.
	 * if outerPlan is NULL, this is no-op (so that the ShareInput node will be
	 * only init-ed once).
	 */

	/*
	 * initialize child nodes
	 *
	 * Like a Material node, we shield the child node from the need to support
	 * BACKWARD, or MARK/RESTORE.
	 */
	eflags &= ~(EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK);

	outerPlan = outerPlan(node);
	childState = ExecInitNode(outerPlan, estate, eflags);
	outerPlanState(sisstate) = childState;

	Assert(node->scan.plan.qual == NULL);
	sisstate->ss.ps.qual = NULL;

	/* Misc initialization 
	 * 
	 * Create expression context 
	 */
	ExecAssignExprContext(estate, &sisstate->ss.ps);

	/* 
	 * Initialize result slot and type.
	 */
	ExecInitResultTupleSlotTL(&sisstate->ss.ps, &TTSOpsMinimalTuple);

	sisstate->ss.ps.ps_ProjInfo = NULL;

	/*
	 * When doing EXPLAIN only, we won't actually execute anything, so don't
	 * bother initializing the state. This isn't merely an optimization:
	 * closing a cross-slice ShareInputScan waits for the consumers to finish,
	 * but if we don't execute anything, it will hang forever.
	 *