protected override BoundRelation RewriteGroupByAndAggregationRelation(BoundGroupByAndAggregationRelation node)
{
var aggregates = RemoveUnusedSlots(node.Aggregates, a => a.Output);
node = node.Update(node.Input, node.Groups, aggregates);
_recorder.Record(node.Aggregates);
_recorder.Record(node.Groups);
return(base.RewriteGroupByAndAggregationRelation(node));
}
private BoundRelation PushOverGroupByAndAggregation(BoundFilterRelation node, BoundGroupByAndAggregationRelation input)
{
// TODO: This may not be that easy.
//
// For example this condition can be pushed:
//
// GroupCol = Value
//
// while this can't:
//
// GroupCol = Value OR Func(const) = const
//
// Formally, a predicate can be pushed over an aggregate if and only if all disjuncts of the predicate's
// CNF do reference at least one grouping column.
BoundExpression remainder = null;
BoundExpression pushed = null;
foreach (var conjunction in Expression.SplitConjunctions(node.Condition))
{
if (conjunction.DependsOnAny(input.GetDefinedValues()))
{
remainder = Expression.And(remainder, conjunction);
}
else
{
pushed = Expression.And(pushed, conjunction);
}
}
var newInputInput = pushed == null
? input.Input
: new BoundFilterRelation(input.Input, pushed);
var newInput = RewriteRelation(input.Update(newInputInput, input.Groups, input.Aggregates));
var newNode = remainder == null
? newInput
: new BoundFilterRelation(newInput, remainder);
return(newNode);
}
