bool pushdownFilter(LogicNode plan, Expr filter, bool pushJoinFilter)
{
// don't push down special expressions
if (filter.VisitEachExists(x => x is MarkerExpr))
{
return(false);
}
switch (filter.TableRefCount())
{
case 0:
// say ?b.b1 = ?a.a1
return(plan.VisitEachExists(n =>
{
if (n is LogicScanTable nodeGet)
{
return nodeGet.AddFilter(filter);
}
return false;
}));
case 1:
return(plan.VisitEachExists(n =>
{
if (n is LogicScanTable nodeGet &&
filter.EqualTableRef(nodeGet.tabref_))
{
return nodeGet.AddFilter(filter);
}
return false;
}));
default:
if (pushJoinFilter)
{
return(plan.PushJoinFilter(filter));
}
return(false);
}
}
