Function execTuplesMatchPrepare

src/backend/executor/execGrouping.c:60–85

* execTuplesMatchPrepare * Build expression that can be evaluated using ExecQual(), returning * whether an ExprContext's inner/outer tuples are NOT DISTINCT */

 *		whether an ExprContext's inner/outer tuples are NOT DISTINCT
 */
ExprState *
execTuplesMatchPrepare(TupleDesc desc,
					   int numCols,
					   const AttrNumber *keyColIdx,
					   const Oid *eqOperators,
					   const Oid *collations,
					   PlanState *parent)
{
	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
	int			i;
	ExprState  *expr;

	if (numCols == 0)
		return NULL;

	/* lookup equality functions */
	for (i = 0; i < numCols; i++)
		eqFunctions[i] = get_opcode(eqOperators[i]);

	/* build actual expression */
	expr = ExecBuildGroupingEqual(desc, desc, NULL, NULL,
								  numCols, keyColIdx, eqFunctions, collations,
								  parent);

	return expr;
}

/*
 * execTuplesHashPrepare