public override ExpressionNode VisitBinaryExpression(BinaryExpression expression)
{
if (expression.Op == BinaryOperator.LogicalAnd)
{
return(base.VisitBinaryExpression(expression));
}
else if (expression.Op == BinaryOperator.Equal)
{
RowBufferEntry[] leftRowBufferEntries = AstUtil.GetRowBufferEntryReferences(expression.Left);
RowBufferEntry[] rightRowBufferEntries = AstUtil.GetRowBufferEntryReferences(expression.Right);
if (leftRowBufferEntries.Length == 1 && rightRowBufferEntries.Length == 1)
{
RowBufferEntry leftRowBufferEntry = leftRowBufferEntries[0];
RowBufferEntry rightRowBufferEntry = rightRowBufferEntries[0];
bool leftIsOuter = IsOuterReference(leftRowBufferEntry);
bool rightIsOuter = IsOuterReference(rightRowBufferEntry);
if (leftRowBufferEntry != rightRowBufferEntry && leftIsOuter ^ rightIsOuter)
{
// Both expressions depend on extactly one row buffer entry but
// they are not refering to the same row buffer entry and
// only one is an outer reference.
SpoolExpression spoolExpression = new SpoolExpression();
if (leftIsOuter)
{
spoolExpression.IndexExpression = expression.Right;
spoolExpression.ProbeExpression = expression.Left;
}
else
{
spoolExpression.IndexExpression = expression.Left;
spoolExpression.ProbeExpression = expression.Right;
}
_spoolExpressions.Add(spoolExpression);
return(LiteralExpression.FromBoolean(true));
}
}
}
return(expression);
}
public override AlgebraNode VisitFilterAlgebraNode(FilterAlgebraNode node)
{
node.Input = VisitAlgebraNode(node.Input);
ExpressionNode originalPredicate = (ExpressionNode)node.Predicate.Clone();
SpoolExpressionExtractor spoolExpressionExtractor = new SpoolExpressionExtractor(_outerReferences);
// HACK: This hack ensures that TRUE literals introduced by SpoolExpressionExtractor are removed.
node.Predicate = AstUtil.CombineConditions(LogicalOperator.And, spoolExpressionExtractor.VisitExpression(node.Predicate));
SpoolExpression[] spoolExpressions = spoolExpressionExtractor.GetSpoolExpressions();
// Now we must check that the remaining filter incl. input to the filter don't reference any other
// outer reference.
bool remainingFilterHasDependenciesToOuterReferences = CheckIfNodeHasDependenciesToOuterReferences(node);
if (remainingFilterHasDependenciesToOuterReferences)
{
// OK; we cannot insert a spool operation here. Undo the expression replacement.
node.Predicate = originalPredicate;
}
else if (spoolExpressions.Length > 0)
{
SpoolExpression spoolExpression = spoolExpressions[0];
AlgebraNode currentInput;
if (node.Predicate is ConstantExpression)
{
currentInput = node.Input;
}
else
{
currentInput = node;
}
RowBufferEntry indexEntry;
RowBufferEntryExpression indexExpressionAsRowBufferEntryExpression = spoolExpression.IndexExpression as RowBufferEntryExpression;
if (indexExpressionAsRowBufferEntryExpression != null)
{
indexEntry = indexExpressionAsRowBufferEntryExpression.RowBufferEntry;
}
else
{
indexEntry = new RowBufferEntry(spoolExpression.IndexExpression.ExpressionType);
ComputedValueDefinition definedValue = new ComputedValueDefinition();
definedValue.Target = indexEntry;
definedValue.Expression = spoolExpression.IndexExpression;
ComputeScalarAlgebraNode computeScalarAlgebraNode = new ComputeScalarAlgebraNode();
computeScalarAlgebraNode.Input = currentInput;
computeScalarAlgebraNode.DefinedValues = new ComputedValueDefinition[] { definedValue };
currentInput = computeScalarAlgebraNode;
}
IndexSpoolAlgebraNode indexSpoolAlgebraNode = new IndexSpoolAlgebraNode();
indexSpoolAlgebraNode.Input = currentInput;
indexSpoolAlgebraNode.IndexEntry = indexEntry;
indexSpoolAlgebraNode.ProbeExpression = spoolExpression.ProbeExpression;
return(indexSpoolAlgebraNode);
}
return(node);
}
public override ExpressionNode VisitBinaryExpression(BinaryExpression expression)
{
if (expression.Op == BinaryOperator.LogicalAnd)
{
return base.VisitBinaryExpression(expression);
}
else if (expression.Op == BinaryOperator.Equal)
{
RowBufferEntry[] leftRowBufferEntries = AstUtil.GetRowBufferEntryReferences(expression.Left);
RowBufferEntry[] rightRowBufferEntries = AstUtil.GetRowBufferEntryReferences(expression.Right);
if (leftRowBufferEntries.Length == 1 && rightRowBufferEntries.Length == 1)
{
RowBufferEntry leftRowBufferEntry = leftRowBufferEntries[0];
RowBufferEntry rightRowBufferEntry = rightRowBufferEntries[0];
bool leftIsOuter = IsOuterReference(leftRowBufferEntry);
bool rightIsOuter = IsOuterReference(rightRowBufferEntry);
if (leftRowBufferEntry != rightRowBufferEntry && leftIsOuter ^ rightIsOuter)
{
// Both expressions depend on extactly one row buffer entry but
// they are not refering to the same row buffer entry and
// only one is an outer reference.
SpoolExpression spoolExpression = new SpoolExpression();
if (leftIsOuter)
{
spoolExpression.IndexExpression = expression.Right;
spoolExpression.ProbeExpression = expression.Left;
}
else
{
spoolExpression.IndexExpression = expression.Left;
spoolExpression.ProbeExpression = expression.Right;
}
_spoolExpressions.Add(spoolExpression);
return LiteralExpression.FromBoolean(true);
}
}
}
return expression;
}
