Function ExecInitUnique

src/backend/executor/nodeUnique.c:115–160

---------------------------------------------------------------- * ExecInitUnique * * This initializes the unique node state structures and * the node's subplan. * ---------------------------------------------------------------- */

 * ----------------------------------------------------------------
 */
UniqueState *
ExecInitUnique(Unique *node, EState *estate, int eflags)
{
	UniqueState *uniquestate;

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

	/*
	 * create state structure
	 */
	uniquestate = makeNode(UniqueState);
	uniquestate->ps.plan = (Plan *) node;
	uniquestate->ps.state = estate;
	uniquestate->ps.ExecProcNode = ExecUnique;

	/*
	 * create expression context
	 */
	ExecAssignExprContext(estate, &uniquestate->ps);

	/*
	 * then initialize outer plan
	 */
	outerPlanState(uniquestate) = ExecInitNode(outerPlan(node), estate, eflags);

	/*
	 * Initialize result slot and type. Unique nodes do no projections, so
	 * initialize projection info for this node appropriately.
	 */
	ExecInitResultTupleSlotTL(&uniquestate->ps, &TTSOpsMinimalTuple);
	uniquestate->ps.ps_ProjInfo = NULL;

	/*
	 * Precompute fmgr lookup data for inner loop
	 */
	uniquestate->eqfunction =
		execTuplesMatchPrepare(ExecGetResultType(outerPlanState(uniquestate)),
							   node->numCols,
							   node->uniqColIdx,
							   node->uniqOperators,
							   node->uniqCollations,
							   &uniquestate->ps);

	return uniquestate;
}

/* ----------------------------------------------------------------
 *		ExecEndUnique