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);
}
private void AddNeededRowBufferEntryReferences(ExpressionNode expression)
{
RowBufferEntry[] rowBufferEntries = AstUtil.GetRowBufferEntryReferences(expression);
foreach (RowBufferEntry rowBufferEntry in rowBufferEntries)
{
AddNeededRowBufferEntry(rowBufferEntry);
}
}
private static bool AndPartHasOuterReference(ExpressionNode andPart, RowBufferEntry[] definedValues)
{
RowBufferEntry[] rowBufferEntries = AstUtil.GetRowBufferEntryReferences(andPart);
foreach (RowBufferEntry rowBufferEntry in rowBufferEntries)
{
if (!ArrayHelpers.Contains(definedValues, rowBufferEntry))
{
return(true);
}
}
return(false);
}
private static ExpressionNode[] GetAndPartsApplicableToJoin(IDictionary <RowBufferEntry, ColumnValueDefinition> introducedColumns, JoinOrder joinOrder, int joinIndex, ICollection <ExpressionNode> andParts, bool removeApplicableAndParts)
{
List <RowBufferEntry> columnsInJoin = new List <RowBufferEntry>();
for (int i = 0; i <= joinIndex; i++)
{
foreach (ColumnRefBinding columnRefBinding in joinOrder.Joins[i].TableRefBinding.ColumnRefs)
{
columnsInJoin.Add(columnRefBinding.ValueDefinition.Target);
}
}
List <ExpressionNode> applicableAndParts = new List <ExpressionNode>();
foreach (ExpressionNode andPart in andParts)
{
RowBufferEntry[] rowBufferEntries = AstUtil.GetRowBufferEntryReferences(andPart);
bool allDependenciesInJoin = true;
foreach (RowBufferEntry entry in rowBufferEntries)
{
if (!columnsInJoin.Contains(entry))
{
// Row buffer entry not available in the join the current position.
// It could be an outer reference. Check if the row buffer entry
// is in the set of introduced row buffer entries.
if (introducedColumns.ContainsKey(entry))
{
allDependenciesInJoin = false;
break;
}
}
}
if (allDependenciesInJoin)
{
applicableAndParts.Add(andPart);
}
}
if (removeApplicableAndParts)
{
foreach (ExpressionNode andPart in applicableAndParts)
{
andParts.Remove(andPart);
}
}
return(applicableAndParts.ToArray());
}
private bool CheckIfNodeHasDependenciesToOuterReferences(AlgebraNode node)
{
foreach (RowBufferEntry rowBufferEntryReference in AstUtil.GetRowBufferEntryReferences(node))
{
foreach (RowBufferEntry[] outerReferences in _outerReferences)
{
if (ArrayHelpers.Contains(outerReferences, rowBufferEntryReference))
{
return(true);
}
}
}
return(false);
}
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];
if (leftRowBufferEntry != rightRowBufferEntry)
{
// Both expressions depend on extactly one row buffer entry but
// they are not refering to the same row buffer entry.
bool leftDependsOnLeft = ArrayHelpers.Contains(_leftDefinedEntries, leftRowBufferEntry);
bool rightDependsOnRight = ArrayHelpers.Contains(_rightDefinedEntries, rightRowBufferEntry);
bool leftDependsOnRight = ArrayHelpers.Contains(_rightDefinedEntries, leftRowBufferEntry);
bool rightDependsOnLeft = ArrayHelpers.Contains(_leftDefinedEntries, rightRowBufferEntry);
if (leftDependsOnRight && rightDependsOnLeft)
{
ExpressionNode oldLeft = expression.Left;
expression.Left = expression.Right;
expression.Right = oldLeft;
leftDependsOnLeft = true;
rightDependsOnRight = true;
}
if (leftDependsOnLeft && rightDependsOnRight)
{
_equalPredicates.Add(expression);
return(LiteralExpression.FromBoolean(true));
}
}
}
}
return(expression);
}
private AlgebraNode PushOverValueDefininingUnary(IEnumerable <ValueDefinition> definedValues, FilterAlgebraNode node)
{
UnaryAlgebraNode inputNode = (UnaryAlgebraNode)node.Input;
List <ExpressionNode> nonDependingAndParts = new List <ExpressionNode>();
List <ExpressionNode> dependingAndParts = new List <ExpressionNode>();
foreach (ExpressionNode andPart in AstUtil.SplitCondition(LogicalOperator.And, node.Predicate))
{
RowBufferEntry[] rowBufferEntries = AstUtil.GetRowBufferEntryReferences(andPart);
bool dependsOnDefinedValue = false;
foreach (ValueDefinition definedValue in definedValues)
{
if (ArrayHelpers.Contains(rowBufferEntries, definedValue.Target))
{
dependsOnDefinedValue = true;
break;
}
}
if (dependsOnDefinedValue)
{
dependingAndParts.Add(andPart);
}
else
{
nonDependingAndParts.Add(andPart);
}
}
if (nonDependingAndParts.Count > 0)
{
node.Predicate = AstUtil.CombineConditions(LogicalOperator.And, dependingAndParts);
inputNode.Input = GetFilterFromAndParts(nonDependingAndParts, inputNode.Input);
if (node.Predicate == null)
{
node.Input = inputNode.Input;
inputNode.Input = VisitAlgebraNode(node);
return(inputNode);
}
}
node.Input = VisitAlgebraNode(node.Input);
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);
}
private static TableRefBinding[] GetTableReferences(IDictionary <RowBufferEntry, ColumnRefBinding> rowBufferColumnDictionary, ExpressionNode expression)
{
List <TableRefBinding> result = new List <TableRefBinding>();
RowBufferEntry[] rowBufferEntries = AstUtil.GetRowBufferEntryReferences(expression);
foreach (RowBufferEntry rowBufferEntry in rowBufferEntries)
{
ColumnRefBinding columnRefBinding;
if (rowBufferColumnDictionary.TryGetValue(rowBufferEntry, out columnRefBinding))
{
if (!result.Contains(columnRefBinding.TableRefBinding))
{
result.Add(columnRefBinding.TableRefBinding);
}
}
}
return(result.ToArray());
}
public override AlgebraNode VisitFilterAlgebraNode(FilterAlgebraNode node)
{
// Check for null rejecting conditions.
foreach (ExpressionNode andPart in AstUtil.SplitCondition(LogicalOperator.And, node.Predicate))
{
RowBufferEntry[] rowBufferEntries = AstUtil.GetRowBufferEntryReferences(andPart);
foreach (RowBufferEntry rowBufferEntry in rowBufferEntries)
{
if (AstUtil.ExpressionYieldsNullOrFalseIfRowBufferEntryNull(andPart, rowBufferEntry))
{
AddNullRejectedTable(rowBufferEntry);
}
}
}
return(base.VisitFilterAlgebraNode(node));
}
private static ExpressionNode ExtractConditionsApplicableToTable(IDictionary <RowBufferEntry, ColumnValueDefinition> introducedColumns, IList <ExpressionNode> conditionList, TableRefBinding tableRefBinding)
{
List <ExpressionNode> applicableConditionList = new List <ExpressionNode>();
for (int i = conditionList.Count - 1; i >= 0; i--)
{
ExpressionNode condition = conditionList[i];
RowBufferEntry[] rowBufferEntries = AstUtil.GetRowBufferEntryReferences(condition);
bool dependentOnOtherTable = false;
foreach (RowBufferEntry rowBufferEntry in rowBufferEntries)
{
ColumnValueDefinition columnValueDefinition;
if (introducedColumns.TryGetValue(rowBufferEntry, out columnValueDefinition))
{
if (columnValueDefinition.ColumnRefBinding.TableRefBinding != tableRefBinding)
{
dependentOnOtherTable = true;
break;
}
}
}
if (!dependentOnOtherTable)
{
conditionList.RemoveAt(i);
applicableConditionList.Add(condition);
}
}
if (applicableConditionList.Count == 0)
{
return(null);
}
ExpressionNode[] applicableConditions = applicableConditionList.ToArray();
return(AstUtil.CombineConditions(LogicalOperator.And, applicableConditions));
}
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);
}
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);
}