private SqlJoin GetLeftOuterWithUnreferencedSingletonOnLeft(SqlSource source)
{
SqlAlias alias = source as SqlAlias;
if (alias != null)
{
SqlSelect select = alias.Node as SqlSelect;
if (select != null &&
select.Where == null &&
select.Top == null &&
select.GroupBy.Count == 0 &&
select.OrderBy.Count == 0)
{
return(this.GetLeftOuterWithUnreferencedSingletonOnLeft(select.From));
}
}
SqlJoin join = source as SqlJoin;
if (join == null || join.JoinType != SqlJoinType.LeftOuter)
{
return(null);
}
if (!this.IsSingletonSelect(join.Left))
{
return(null);
}
HashSet <SqlAlias> p = SqlGatherProducedAliases.Gather(join.Left);
HashSet <SqlAlias> c = SqlGatherConsumedAliases.Gather(join.Right);
if (p.Overlaps(c))
{
return(null);
}
return(join);
}
internal override SqlSource VisitJoin(SqlJoin join)
{
if (join.JoinType == SqlJoinType.CrossApply)
{
// Look down the left side to see what table aliases are produced.
HashSet <SqlAlias> p = SqlGatherProducedAliases.Gather(join.Left);
// Look down the right side to see what table aliases are consumed.
HashSet <SqlAlias> c = SqlGatherConsumedAliases.Gather(join.Right);
// Look at each consumed alias and see if they are mentioned in produced.
if (p.Overlaps(c))
{
Annotations.Add(join, new CompatibilityAnnotation(Strings.SourceExpressionAnnotation(join.SourceExpression), _providerModesWithIncompatibilities));
// Can't reduce because this consumed alias is produced on the left.
return(base.VisitJoin(join));
}
// Can turn this into a CROSS JOIN
join.JoinType = SqlJoinType.Cross;
return(VisitJoin(join));
}
return(base.VisitJoin(join));
}
