public override CGroupMember Apply(CGroupMember expr)
{
LogicJoin a_bc = expr.logic_ as LogicJoin;
LogicNode a = (a_bc.l_() as LogicMemoRef).Deref <LogicNode>();
LogicJoin bc = (a_bc.r_() as LogicMemoRef).Deref <LogicJoin>();
Expr bcfilter = bc.filter_;
var ab = new LogicJoin(a_bc.l_(), bc.l_());
var c = bc.r_();
var ab_c = new LogicJoin(ab, c);
Debug.Assert(!a.LeftReferencesRight(bc));
if (ab.LeftReferencesRight(c))
{
return(expr);
}
// pull up all join filters and re-push them back
Expr allfilters = bcfilter;
if (a_bc.filter_ != null)
{
allfilters = allfilters.AddAndFilter(a_bc.filter_);
}
if (allfilters != null)
{
var andlist = allfilters.FilterToAndList();
andlist.RemoveAll(e => ab_c.PushJoinFilter(e));
if (andlist.Count > 0)
{
ab_c.filter_ = andlist.AndListToExpr();
}
}
// Ideally if there is no cross join in the given plan but cross join
// in the new plan, we shall return the original plan. However, stop
// exploration now will prevent generating other promising plans. So
// we have to return the new plan.
//
if (expr.QueryOption().optimize_.memo_disable_crossjoin_)
{
if (a_bc.filter_ != null && bcfilter != null)
{
if (ab_c.filter_ is null || ab.filter_ is null)
{
return(expr);
}
}
}
return(new CGroupMember(ab_c, expr.group_));
}