Function cdbpathlocus_get_distkey_exprs

src/backend/cdb/cdbpathlocus.c:564–607

* cdbpathlocus_get_distkey_exprs * * Returns a List with one Expr for each distkey column. Each item either is * in the given targetlist, or has no Var nodes that are not in the targetlist; * and uses only rels in the given set of relids. Returns NIL if the * distkey cannot be expressed in terms of the given relids and targetlist. */

 * distkey cannot be expressed in terms of the given relids and targetlist.
 */
void
cdbpathlocus_get_distkey_exprs(CdbPathLocus locus,
							   Bitmapset *relids,
							   List *targetlist,
							   List **exprs_p,
							   List **opfamilies_p)
{
	List	   *result_exprs = NIL;
	List	   *result_opfamilies = NIL;
	ListCell   *distkeycell;

	Assert(cdbpathlocus_is_valid(locus));

	*exprs_p = NIL;
	*opfamilies_p = NIL;

	if (CdbPathLocus_IsHashed(locus) || CdbPathLocus_IsHashedOJ(locus) || CdbPathLocus_IsHashedWorkers(locus))
	{
		foreach(distkeycell, locus.distkey)
		{
			DistributionKey *distkey = (DistributionKey *) lfirst(distkeycell);
			ListCell   *ec_cell;
			Expr	   *item = NULL;

			foreach(ec_cell, distkey->dk_eclasses)
			{
				EquivalenceClass *dk_eclass = (EquivalenceClass *) lfirst(ec_cell);

				item = cdbpullup_findEclassInTargetList(dk_eclass, targetlist,
														distkey->dk_opfamily, NULL);

				if (item)
					break;
			}
			if (!item)
				return;

			result_exprs = lappend(result_exprs, item);
			result_opfamilies = lappend_oid(result_opfamilies, distkey->dk_opfamily);
		}
		*exprs_p = result_exprs;
		*opfamilies_p = result_opfamilies;
	}
}								/* cdbpathlocus_get_distkey_exprs */


/*