Function ExecInitProjectSet

src/backend/executor/nodeProjectSet.c:219–312

---------------------------------------------------------------- * ExecInitProjectSet * * Creates the run-time state information for the ProjectSet node * produced by the planner and initializes outer relations * (child nodes). * ---------------------------------------------------------------- */

 * ----------------------------------------------------------------
 */
ProjectSetState *
ExecInitProjectSet(ProjectSet *node, EState *estate, int eflags)
{
	ProjectSetState *state;
	ListCell   *lc;
	int			off;

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

	/*
	 * create state structure
	 */
	state = makeNode(ProjectSetState);
	state->ps.plan = (Plan *) node;
	state->ps.state = estate;
	state->ps.ExecProcNode = ExecProjectSet;

	state->pending_srf_tuples = false;

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

	/*
	 * initialize child nodes
	 */
	outerPlanState(state) = ExecInitNode(outerPlan(node), estate, eflags);

	/*
	 * we don't use inner plan
	 */
	Assert(innerPlan(node) == NULL);

	/*
	 * tuple table and result type initialization
	 */
	ExecInitResultTupleSlotTL(&state->ps, &TTSOpsVirtual);

	/* Create workspace for per-tlist-entry expr state & SRF-is-done state */
	state->nelems = list_length(node->plan.targetlist);
	state->elems = (Node **)
		palloc(sizeof(Node *) * state->nelems);
	state->elemdone = (ExprDoneCond *)
		palloc(sizeof(ExprDoneCond) * state->nelems);

	/*
	 * Build expressions to evaluate targetlist.  We can't use
	 * ExecBuildProjectionInfo here, since that doesn't deal with SRFs.
	 * Instead compile each expression separately, using
	 * ExecInitFunctionResultSet where applicable.
	 */
	off = 0;
	foreach(lc, node->plan.targetlist)
	{