private AlgebraNode PushOverJoin(ComputeScalarAlgebraNode node)
{
JoinAlgebraNode joinAlgebraNode = (JoinAlgebraNode)node.Input;
RowBufferEntry[] leftDefinedValues = AstUtil.GetDefinedValueEntries(joinAlgebraNode.Left);
RowBufferEntry[] rightDefinedValues = AstUtil.GetDefinedValueEntries(joinAlgebraNode.Right);
List <ComputedValueDefinition> remainingValueDefinitions = new List <ComputedValueDefinition>();
List <ComputedValueDefinition> leftPushedValueDefinitions = new List <ComputedValueDefinition>();
List <ComputedValueDefinition> rightPushedValueDefinitions = new List <ComputedValueDefinition>();
bool canPushToLeftSide = joinAlgebraNode.Op != JoinAlgebraNode.JoinOperator.RightOuterJoin &&
joinAlgebraNode.Op != JoinAlgebraNode.JoinOperator.FullOuterJoin;
bool canPushToRightSide = joinAlgebraNode.Op != JoinAlgebraNode.JoinOperator.LeftOuterJoin &&
joinAlgebraNode.Op != JoinAlgebraNode.JoinOperator.FullOuterJoin;
foreach (ComputedValueDefinition valueDefinition in node.DefinedValues)
{
RowBufferEntry[] referencedValues = AstUtil.GetRowBufferEntryReferences(valueDefinition.Expression);
bool referencesProbeColumn = ArrayHelpers.Contains(referencedValues, joinAlgebraNode.ProbeBufferEntry);
if (!referencesProbeColumn && canPushToLeftSide && AstUtil.DoesNotReference(referencedValues, rightDefinedValues))
{
leftPushedValueDefinitions.Add(valueDefinition);
}
else if (!referencesProbeColumn && canPushToRightSide && AstUtil.DoesNotReference(referencedValues, leftDefinedValues))
{
rightPushedValueDefinitions.Add(valueDefinition);
}
else
{
remainingValueDefinitions.Add(valueDefinition);
}
}
if (leftPushedValueDefinitions.Count > 0)
{
ComputeScalarAlgebraNode computeScalarAlgebraNode = new ComputeScalarAlgebraNode();
computeScalarAlgebraNode.DefinedValues = leftPushedValueDefinitions.ToArray();
computeScalarAlgebraNode.Input = joinAlgebraNode.Left;
joinAlgebraNode.Left = VisitAlgebraNode(computeScalarAlgebraNode);
}
if (rightPushedValueDefinitions.Count > 0)
{
ComputeScalarAlgebraNode computeScalarAlgebraNode = new ComputeScalarAlgebraNode();
computeScalarAlgebraNode.DefinedValues = rightPushedValueDefinitions.ToArray();
computeScalarAlgebraNode.Input = joinAlgebraNode.Right;
joinAlgebraNode.Right = VisitAlgebraNode(computeScalarAlgebraNode);
}
if (remainingValueDefinitions.Count == 0)
{
return(joinAlgebraNode);
}
node.DefinedValues = remainingValueDefinitions.ToArray();
return(node);
}
public override AlgebraNode VisitJoinAlgebraNode(JoinAlgebraNode node)
{
// Get declared tables of left and right
RowBufferEntry[] leftDefinedValues = AstUtil.GetDefinedValueEntries(node.Left);
RowBufferEntry[] rightDefinedValues = AstUtil.GetDefinedValueEntries(node.Right);
// Analyze AND-parts of Condition
if (node.Predicate != null)
{
List <ExpressionNode> leftAndParts = new List <ExpressionNode>();
List <ExpressionNode> rightAndParts = new List <ExpressionNode>();
List <ExpressionNode> remainingAndParts = new List <ExpressionNode>();
foreach (ExpressionNode andPart in AstUtil.SplitCondition(LogicalOperator.And, node.Predicate))
{
// Check if we can push this AND-part down.
if (AstUtil.AllowsLeftPushDown(node.Op) && AstUtil.ExpressionDoesNotReference(andPart, rightDefinedValues))
{
leftAndParts.Add(andPart);
}
else if (AstUtil.AllowsRightPushDown(node.Op) && AstUtil.ExpressionDoesNotReference(andPart, leftDefinedValues))
{
rightAndParts.Add(andPart);
}
else
{
remainingAndParts.Add(andPart);
}
}
if (leftAndParts.Count > 0)
{
node.Left = GetFilterFromAndParts(leftAndParts, node.Left);
}
if (rightAndParts.Count > 0)
{
node.Right = GetFilterFromAndParts(rightAndParts, node.Right);
}
node.Predicate = AstUtil.CombineConditions(LogicalOperator.And, remainingAndParts);
}
// Visit children
node.Left = VisitAlgebraNode(node.Left);
node.Right = VisitAlgebraNode(node.Right);
return(node);
}
public override AlgebraNode VisitJoinAlgebraNode(JoinAlgebraNode node)
{
// Get declared tables of left and right
RowBufferEntry[] leftDefinedValues = AstUtil.GetDefinedValueEntries(node.Left);
RowBufferEntry[] rightDefinedValues = AstUtil.GetDefinedValueEntries(node.Right);
// Replace outer joins by left-/right-/inner joins
if (node.Op == JoinAlgebraNode.JoinOperator.RightOuterJoin ||
node.Op == JoinAlgebraNode.JoinOperator.FullOuterJoin)
{
if (IsAnyNullRejected(leftDefinedValues))
{
if (node.Op == JoinAlgebraNode.JoinOperator.RightOuterJoin)
{
node.Op = JoinAlgebraNode.JoinOperator.InnerJoin;
}
else
{
node.Op = JoinAlgebraNode.JoinOperator.LeftOuterJoin;
}
}
}
if (node.Op == JoinAlgebraNode.JoinOperator.LeftOuterJoin ||
node.Op == JoinAlgebraNode.JoinOperator.FullOuterJoin)
{
if (IsAnyNullRejected(rightDefinedValues))
{
if (node.Op == JoinAlgebraNode.JoinOperator.LeftOuterJoin)
{
node.Op = JoinAlgebraNode.JoinOperator.InnerJoin;
}
else
{
node.Op = JoinAlgebraNode.JoinOperator.RightOuterJoin;
}
}
}
// After converting an outer join to an inner one we can
// sometimes eliminate the whole join.
if (node.Op == JoinAlgebraNode.JoinOperator.InnerJoin)
{
// TODO: There is a problem. If the constant scan defines values this does not work. Acutally,
// this is currently no problem as the only way to create such a plan is using derived
// tables and in this phase the child will be a ResultNode.
if (node.Left is ConstantScanAlgebraNode)
{
return(VisitAlgebraNode(WrapWithFilter(node.Right, node.Predicate)));
}
if (node.Right is ConstantScanAlgebraNode)
{
return(VisitAlgebraNode(WrapWithFilter(node.Left, node.Predicate)));
}
}
// Analyze AND-parts of Condition
if (node.Predicate == null)
{
// TODO: This does not work as the children are not yet rearranged.
if (node.Op == JoinAlgebraNode.JoinOperator.LeftOuterJoin ||
node.Op == JoinAlgebraNode.JoinOperator.RightOuterJoin)
{
bool hasOuterReferences = AstUtil.GetOuterReferences(node).Length == 0;
if (!hasOuterReferences)
{
if (node.Op == JoinAlgebraNode.JoinOperator.LeftOuterJoin && AstUtil.WillProduceAtLeastOneRow(node.Right) ||
node.Op == JoinAlgebraNode.JoinOperator.RightOuterJoin && AstUtil.WillProduceAtLeastOneRow(node.Left))
{
node.Op = JoinAlgebraNode.JoinOperator.InnerJoin;
return(VisitAlgebraNode(node));
}
}
}
}
else
{
foreach (ExpressionNode andPart in AstUtil.SplitCondition(LogicalOperator.And, node.Predicate))
{
if (node.Op != JoinAlgebraNode.JoinOperator.FullOuterJoin)
{
// Check if we can derive from this AND-part that a table it depends on
// is null-rejected.
RowBufferEntry[] rowBufferEntries = AstUtil.GetRowBufferEntryReferences(andPart);
foreach (RowBufferEntry rowBufferEntry in rowBufferEntries)
{
if (AstUtil.ExpressionYieldsNullOrFalseIfRowBufferEntryNull(andPart, rowBufferEntry))
{
if (ArrayHelpers.Contains(leftDefinedValues, rowBufferEntry) &&
node.Op != JoinAlgebraNode.JoinOperator.LeftOuterJoin)
{
AddNullRejectedTable(rowBufferEntry);
}
else if (ArrayHelpers.Contains(rightDefinedValues, rowBufferEntry) &&
node.Op != JoinAlgebraNode.JoinOperator.RightOuterJoin)
{
AddNullRejectedTable(rowBufferEntry);
}
}
}
}
}
}
// Visit children
node.Left = VisitAlgebraNode(node.Left);
node.Right = VisitAlgebraNode(node.Right);
return(node);
}
public override AlgebraNode VisitJoinAlgebraNode(JoinAlgebraNode node)
{
node.Left = VisitAlgebraNode(node.Left);
node.Right = VisitAlgebraNode(node.Right);
// Get defined values of left and right
RowBufferEntry[] leftDefinedValues = AstUtil.GetDefinedValueEntries(node.Left);
RowBufferEntry[] rightDefinedValues = AstUtil.GetDefinedValueEntries(node.Right);
List <ExpressionNode> andPartsWithinJoin = new List <ExpressionNode>();
// Try to pull up AND-parts that contain outer references from a left sided filter and combine
// them with the join predicate.
//
// NOTE: This is only possible if the join is not a LEFT OUTER or FULL OUTER JOIN since this
// operation would change the join's semantic.
if (node.Op != JoinAlgebraNode.JoinOperator.LeftOuterJoin &&
node.Op != JoinAlgebraNode.JoinOperator.FullOuterJoin)
{
FilterAlgebraNode leftAsFilter = node.Left as FilterAlgebraNode;
if (leftAsFilter != null)
{
List <ExpressionNode> remainingAndParts = new List <ExpressionNode>();
foreach (ExpressionNode andPart in AstUtil.SplitCondition(LogicalOperator.And, leftAsFilter.Predicate))
{
if (AndPartHasOuterReference(andPart, leftDefinedValues))
{
andPartsWithinJoin.Add(andPart);
}
else
{
remainingAndParts.Add(andPart);
}
}
leftAsFilter.Predicate = AstUtil.CombineConditions(LogicalOperator.And, remainingAndParts);
if (leftAsFilter.Predicate == null)
{
node.Left = leftAsFilter.Input;
}
}
}
// Try to pull up AND-parts that contain outer references from a right sided filter and combine
// them with the join predicate.
//
// NOTE: This is only possible if the join is not a RIGHT OUTER or FULL OUTER JOIN since this
// operation would change the join's semantic.
if (node.Op != JoinAlgebraNode.JoinOperator.RightOuterJoin &&
node.Op != JoinAlgebraNode.JoinOperator.FullOuterJoin)
{
FilterAlgebraNode rightAsFilter = node.Right as FilterAlgebraNode;
if (rightAsFilter != null)
{
List <ExpressionNode> remainingAndParts = new List <ExpressionNode>();
foreach (ExpressionNode andPart in AstUtil.SplitCondition(LogicalOperator.And, rightAsFilter.Predicate))
{
if (AndPartHasOuterReference(andPart, rightDefinedValues))
{
andPartsWithinJoin.Add(andPart);
}
else
{
remainingAndParts.Add(andPart);
}
}
rightAsFilter.Predicate = AstUtil.CombineConditions(LogicalOperator.And, remainingAndParts);
if (rightAsFilter.Predicate == null)
{
node.Right = rightAsFilter.Input;
}
}
}
// If we found any AND-parts that could be pulled up, merge them with the join predicate.
if (andPartsWithinJoin.Count > 0)
{
node.Predicate = AstUtil.CombineConditions(LogicalOperator.And, node.Predicate, AstUtil.CombineConditions(LogicalOperator.And, andPartsWithinJoin));
}
// Now we try to extract AND-parts that contain outer references from the join predicate itself.
//
// NOTE: This is only possible if the node is not an OUTER JOIN. If the node is a SEMI JOIN the
// operation is only legal if the AND-part does not reference any columns from the side that is
// is used as filter criteria (i.e. for LSJ this is the right side, for RSJ this is the left
// side).
if (node.Op != JoinAlgebraNode.JoinOperator.LeftOuterJoin &&
node.Op != JoinAlgebraNode.JoinOperator.RightOuterJoin &&
node.Op != JoinAlgebraNode.JoinOperator.FullOuterJoin &&
node.Predicate != null)
{
List <ExpressionNode> andPartsAboveJoin = new List <ExpressionNode>();
List <ExpressionNode> remainingAndParts = new List <ExpressionNode>();
foreach (ExpressionNode andPart in AstUtil.SplitCondition(LogicalOperator.And, node.Predicate))
{
if (AndPartHasOuterReference(andPart, leftDefinedValues, rightDefinedValues) &&
SemiJoinDoesNotDependOn(node.Op, andPart, leftDefinedValues, rightDefinedValues))
{
andPartsAboveJoin.Add(andPart);
}
else
{
remainingAndParts.Add(andPart);
}
}
node.Predicate = AstUtil.CombineConditions(LogicalOperator.And, remainingAndParts);
if (andPartsAboveJoin.Count > 0)
{
FilterAlgebraNode filterAlgebraNode = new FilterAlgebraNode();
filterAlgebraNode.Predicate = AstUtil.CombineConditions(LogicalOperator.And, andPartsAboveJoin);
filterAlgebraNode.Input = node;
return(filterAlgebraNode);
}
}
return(node);
}
private AlgebraNode PushOverJoin(FilterAlgebraNode node)
{
JoinAlgebraNode inputNode = (JoinAlgebraNode)node.Input;
// Get declared tables of left and right
RowBufferEntry[] leftDefinedValues = AstUtil.GetDefinedValueEntries(inputNode.Left);
RowBufferEntry[] rightDefinedValues = AstUtil.GetDefinedValueEntries(inputNode.Right);
// Obviously, we cannot merge the filter with the join if the join is an outer join
// (since it would change the join's semantics).
//
// Another less obvious restriction is that we cannot merge a filter with the join if
// the join has a passthru predicate. In case the passthru predicte evaluates to true
// the filter would not be applied. However, we are allowed to push the filter the over
// join.
bool canMerge = inputNode.Op != JoinAlgebraNode.JoinOperator.FullOuterJoin &&
inputNode.Op != JoinAlgebraNode.JoinOperator.LeftOuterJoin &&
inputNode.Op != JoinAlgebraNode.JoinOperator.RightOuterJoin &&
inputNode.PassthruPredicate == null;
if (canMerge)
{
// We can merge the filter with the condition of the join.
//
// However, we have to make sure that the predicate does not reference the probe column.
// Since not having a probe column is the most common case, we don't always split the
// predicate into conjuncts.
if (inputNode.ProbeBufferEntry == null || !ArrayHelpers.Contains(AstUtil.GetRowBufferEntryReferences(node.Predicate), inputNode.ProbeBufferEntry))
{
// Either there is no probe column defined or the filter does not reference it. That means
// no splitting necessary, we can just merge the whole predicate with the join predicate.
inputNode.Predicate = AstUtil.CombineConditions(LogicalOperator.And, inputNode.Predicate, node.Predicate);
return(VisitAlgebraNode(inputNode));
}
else
{
// Unfortunately, the filter references the probe column. Now let's check whether we can merge
// conjuncts of the predicate.
List <ExpressionNode> remainingAndParts = new List <ExpressionNode>();
List <ExpressionNode> mergableAndParts = new List <ExpressionNode>();
foreach (ExpressionNode andPart in AstUtil.SplitCondition(LogicalOperator.And, node.Predicate))
{
bool andPartReferencesProbeColumn = ArrayHelpers.Contains(AstUtil.GetRowBufferEntryReferences(andPart), inputNode.ProbeBufferEntry);
if (andPartReferencesProbeColumn)
{
remainingAndParts.Add(andPart);
}
else
{
mergableAndParts.Add(andPart);
}
}
if (mergableAndParts.Count > 0)
{
ExpressionNode combinedMergableAndParts = AstUtil.CombineConditions(LogicalOperator.And, mergableAndParts.ToArray());
inputNode.Predicate = AstUtil.CombineConditions(LogicalOperator.And, inputNode.Predicate, combinedMergableAndParts);
node.Predicate = AstUtil.CombineConditions(LogicalOperator.And, remainingAndParts);
if (node.Predicate == null)
{
return(VisitAlgebraNode(inputNode));
}
}
}
}
else
{
// The condition cannot be merged. Now we try to push AND-parts over the join.
List <ExpressionNode> leftAndParts = new List <ExpressionNode>();
List <ExpressionNode> rightAndParts = new List <ExpressionNode>();
List <ExpressionNode> remainingAndParts = new List <ExpressionNode>();
foreach (ExpressionNode andPart in AstUtil.SplitCondition(LogicalOperator.And, node.Predicate))
{
bool andPartReferencesProbeColumn = inputNode.ProbeBufferEntry != null &&
ArrayHelpers.Contains(AstUtil.GetRowBufferEntryReferences(andPart), inputNode.ProbeBufferEntry);
if (!andPartReferencesProbeColumn && AstUtil.AllowsLeftPushOver(inputNode.Op) && AstUtil.ExpressionDoesNotReference(andPart, rightDefinedValues))
{
// The AND-part depends only on the LHS and the join is inner/left.
// So we are allowed to push this AND-part down.
leftAndParts.Add(andPart);
}
else if (!andPartReferencesProbeColumn && AstUtil.AllowsRightPushOver(inputNode.Op) && AstUtil.ExpressionDoesNotReference(andPart, leftDefinedValues))
{
// The AND-part depends only on the RHS and the join is inner/right.
// So we are allowed to push this AND-part down.
rightAndParts.Add(andPart);
}
else
{
remainingAndParts.Add(andPart);
}
}
if (leftAndParts.Count > 0)
{
inputNode.Left = GetFilterFromAndParts(leftAndParts, inputNode.Left);
}
if (rightAndParts.Count > 0)
{
inputNode.Right = GetFilterFromAndParts(rightAndParts, inputNode.Right);
}
node.Predicate = AstUtil.CombineConditions(LogicalOperator.And, remainingAndParts);
if (node.Predicate == null)
{
return(VisitAlgebraNode(inputNode));
}
}
node.Input = VisitAlgebraNode(node.Input);
return(node);
}
public override AlgebraNode VisitJoinAlgebraNode(JoinAlgebraNode node)
{
node.Left = VisitAlgebraNode(node.Left);
node.Right = VisitAlgebraNode(node.Right);
if (node.Predicate != null &&
(node.OuterReferences == null || node.OuterReferences.Length == 0) &&
(
node.Op == JoinAlgebraNode.JoinOperator.InnerJoin ||
node.Op == JoinAlgebraNode.JoinOperator.LeftOuterJoin ||
node.Op == JoinAlgebraNode.JoinOperator.RightOuterJoin ||
node.Op == JoinAlgebraNode.JoinOperator.FullOuterJoin)
)
{
RowBufferEntry[] leftDefinedEntries = AstUtil.GetDefinedValueEntries(node.Left);
RowBufferEntry[] rightDefinedEntries = AstUtil.GetDefinedValueEntries(node.Right);
EqualPredicatesExtractor equalPredicatesExtractor = new EqualPredicatesExtractor(leftDefinedEntries, rightDefinedEntries);
ExpressionNode probeResidual = equalPredicatesExtractor.VisitExpression(node.Predicate);
BinaryExpression[] equalPredicates = equalPredicatesExtractor.GetEqualPredicates();
if (equalPredicates.Length > 0)
{
BinaryExpression equalPredicate = equalPredicates[0];
ExpressionBuilder expressionBuilder = new ExpressionBuilder();
expressionBuilder.Push(probeResidual);
if (equalPredicates.Length > 1)
{
for (int i = 1; i < equalPredicates.Length; i++)
{
expressionBuilder.Push(equalPredicates[i]);
}
expressionBuilder.PushNAry(LogicalOperator.And);
}
probeResidual = expressionBuilder.Pop();
if (probeResidual is ConstantExpression)
{
probeResidual = null;
}
AlgebraNode leftInput = node.Left;
AlgebraNode rightInput = node.Right;
if (node.Op == JoinAlgebraNode.JoinOperator.LeftOuterJoin)
{
node.Op = JoinAlgebraNode.JoinOperator.RightOuterJoin;
leftInput = node.Right;
rightInput = node.Left;
ExpressionNode oldLeft = equalPredicate.Left;
equalPredicate.Left = equalPredicate.Right;
equalPredicate.Right = oldLeft;
}
RowBufferEntry leftEntry;
RowBufferEntryExpression leftAsRowBufferEntryExpression = equalPredicate.Left as RowBufferEntryExpression;
if (leftAsRowBufferEntryExpression != null)
{
leftEntry = leftAsRowBufferEntryExpression.RowBufferEntry;
}
else
{
leftEntry = new RowBufferEntry(equalPredicate.Left.ExpressionType);
ComputedValueDefinition definedValue = new ComputedValueDefinition();
definedValue.Target = leftEntry;
definedValue.Expression = equalPredicate.Left;
ComputeScalarAlgebraNode computeScalarAlgebraNode = new ComputeScalarAlgebraNode();
computeScalarAlgebraNode.Input = leftInput;
computeScalarAlgebraNode.DefinedValues = new ComputedValueDefinition[] { definedValue };
leftInput = computeScalarAlgebraNode;
}
RowBufferEntry rightEntry;
RowBufferEntryExpression rightAsRowBufferEntryExpression = equalPredicate.Right as RowBufferEntryExpression;
if (rightAsRowBufferEntryExpression != null)
{
rightEntry = rightAsRowBufferEntryExpression.RowBufferEntry;
}
else
{
rightEntry = new RowBufferEntry(equalPredicate.Right.ExpressionType);
ComputedValueDefinition definedValue = new ComputedValueDefinition();
definedValue.Target = rightEntry;
definedValue.Expression = equalPredicate.Right;
ComputeScalarAlgebraNode computeScalarAlgebraNode = new ComputeScalarAlgebraNode();
computeScalarAlgebraNode.Input = rightInput;
computeScalarAlgebraNode.DefinedValues = new ComputedValueDefinition[] { definedValue };
rightInput = computeScalarAlgebraNode;
}
HashMatchAlgebraNode hashMatchAlgebraNode = new HashMatchAlgebraNode();
hashMatchAlgebraNode.Op = node.Op;
hashMatchAlgebraNode.Left = leftInput;
hashMatchAlgebraNode.Right = rightInput;
hashMatchAlgebraNode.BuildKeyEntry = leftEntry;
hashMatchAlgebraNode.ProbeEntry = rightEntry;
hashMatchAlgebraNode.ProbeResidual = probeResidual;
return(hashMatchAlgebraNode);
}
}
return(node);
}
