protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
// A <IJ> (B <J> C) --> (A <IJ> B) <J> C
if (node.JoinType != BoundJoinType.Inner)
{
return(base.RewriteJoinRelation(node));
}
var rightSide = node.Right as BoundJoinRelation;
if (rightSide == null || rightSide.Probe != null || rightSide.PassthruPredicate != null)
{
return(base.RewriteJoinRelation(node));
}
var leftSideLeft = RewriteRelation(node.Left);
var leftSideRight = rightSide.Left;
var left = new BoundJoinRelation(node.JoinType, leftSideLeft, leftSideRight, null, null, null);
var right = rightSide.Right;
var condition = Expression.And(node.Condition, rightSide.Condition);
var result = new BoundJoinRelation(rightSide.JoinType, left, right, condition, null, null);
return(RewriteRelation(result));
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
node = (BoundJoinRelation)base.RewriteJoinRelation(node);
var needsRewriting = NeedsRewriting(node);
if (!needsRewriting)
{
return(node);
}
var node1 = (BoundJoinRelation)Instatiator.Instantiate(node);
var node2 = (BoundJoinRelation)Instatiator.Instantiate(node);
var leftOuterJoin = node1.Update(BoundJoinType.LeftOuter, node1.Left, node1.Right, node1.Condition, null, null);
var leftAntiSemiJoin = node1.Update(BoundJoinType.LeftAntiSemi, node2.Right, node2.Left, node2.Condition, null, null);
var computedValueSlots = node.Left.GetOutputValues().Select(v => v.Duplicate()).ToImmutableArray();
var computedValues = computedValueSlots.Select(v => new BoundComputedValue(Expression.Null(), v));
var compute = new BoundComputeRelation(leftAntiSemiJoin, computedValues);
var project = new BoundProjectRelation(compute, computedValueSlots.Concat(leftAntiSemiJoin.GetOutputValues()));
var concatValueSlots = node.GetOutputValues().ToImmutableArray();
var firstOutputs = leftOuterJoin.GetOutputValues().ToImmutableArray();
var secondOutputs = project.GetOutputValues().ToImmutableArray();
var unifiedValues = new BoundUnifiedValue[concatValueSlots.Length];
for (var i = 0; i < unifiedValues.Length; i++)
{
unifiedValues[i] = new BoundUnifiedValue(concatValueSlots[i], new[] { firstOutputs[i], secondOutputs[i] });
}
return(new BoundConcatenationRelation(new BoundRelation[] { leftOuterJoin, project }, unifiedValues));
}
private static BoundRelation RewriteDisjunctions(BoundExpression condition)
{
var scalarPredicates = new List <BoundExpression>();
var relationalPredicates = new List <BoundRelation>();
foreach (var disjunction in Expression.SplitDisjunctions(condition))
{
BoundExistsSubselect exists;
bool isNegated;
if (TryGetExistsSubselect(disjunction, out exists, out isNegated))
{
if (!isNegated)
{
relationalPredicates.Add(exists.Relation);
}
else
{
var constantRelation = new BoundConstantRelation();
var predicate = new BoundJoinRelation(BoundJoinType.LeftAntiSemi, constantRelation, exists.Relation, null, null, null);
relationalPredicates.Add(predicate);
}
}
else if (Expression.IsConjunction(disjunction))
{
var constantRelation = new BoundConstantRelation();
var output = RewriteConjunctions(constantRelation, disjunction);
if (output == null)
{
scalarPredicates.Add(disjunction);
}
else
{
var predicate = new BoundJoinRelation(BoundJoinType.LeftSemi, constantRelation, output, null, null, null);
relationalPredicates.Add(predicate);
}
}
else
{
scalarPredicates.Add(disjunction);
}
}
if (relationalPredicates.Count == 0)
{
return(null);
}
if (scalarPredicates.Count > 0)
{
var constantRelation = new BoundConstantRelation();
var predicate = Expression.Or(scalarPredicates);
var filter = new BoundFilterRelation(constantRelation, predicate);
relationalPredicates.Insert(0, filter);
}
return(new BoundConcatenationRelation(relationalPredicates, Enumerable.Empty <BoundUnifiedValue>()));
}
private static BoundRelation RewriteConjunctions(BoundRelation input, BoundExpression condition)
{
var current = input;
var scalarPredicates = new List <BoundExpression>();
var conjunctions = Expression.SplitConjunctions(condition);
foreach (var conjunction in conjunctions)
{
BoundExistsSubselect exists;
bool isNegated;
if (TryGetExistsSubselect(conjunction, out exists, out isNegated))
{
var joinType = isNegated
? BoundJoinType.LeftAntiSemi
: BoundJoinType.LeftSemi;
current = new BoundJoinRelation(joinType, current, exists.Relation, null, null, null);
}
else if (Expression.IsDisjunction(conjunction))
{
var relation = RewriteDisjunctions(conjunction);
if (relation != null)
{
current = new BoundJoinRelation(BoundJoinType.LeftSemi, current, relation, null, null, null);
}
else
{
scalarPredicates.Add(conjunction);
}
}
else
{
scalarPredicates.Add(conjunction);
}
}
// If we haven't done anything, simply return null to indicate to our
// caller that the condition only contained scalars.
if (current == input)
{
return(null);
}
// If we have no scalar predicates left, it means the condition only
// contained EXISTs queries, so we can return the current node.
if (scalarPredicates.Count == 0)
{
return(current);
}
// Othwerwise We add a filter for the scalars.
var predicate = Expression.And(scalarPredicates);
return(new BoundFilterRelation(current, predicate));
}
public static IEnumerable <ValueSlot> GetOuterReferences(BoundJoinRelation node)
{
var valueSlotDependencyFinder = new ValueSlotDependencyFinder();
valueSlotDependencyFinder.VisitRelation(node.Right);
var usedValueSlots = valueSlotDependencyFinder.ValueSlots;
return(node.Left.GetDefinedValues().Where(usedValueSlots.Contains));
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
if (node.JoinType == BoundJoinType.RightOuter)
{
var newLeft = node.Right;
var newRight = node.Left;
node = node.Update(BoundJoinType.LeftOuter, newLeft, newRight, node.Condition, node.Probe, node.PassthruPredicate);
}
return(base.RewriteJoinRelation(node));
}
private static ShowPlanNode BuildJoin(BoundJoinRelation node)
{
var outerReferences = GetOuterReferences(node);
var probe = node.Probe == null ? string.Empty : $", ProbeColumn := {node.Probe}";
var passthru = node.PassthruPredicate == null ? string.Empty : $", Passthru := {node.PassthruPredicate}";
var name = $"{node.JoinType}Join{outerReferences}{probe}{passthru}";
var properties = Enumerable.Empty <KeyValuePair <string, string> >();
var leftAndRight = new[] { Build(node.Left), Build(node.Right) };
var children = node.Condition == null
? leftAndRight
: leftAndRight.Concat(new[] { Build(node.Condition) });
return(new ShowPlanNode(name, properties, children));
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
var newLeft = RewriteRelation(node.Left);
bool semiJoinContext;
semiJoinContext = (node.JoinType == BoundJoinType.LeftSemi ||
node.JoinType == BoundJoinType.LeftAntiSemi);
_semiJoinContextFlagStack.Push(semiJoinContext);
var newRight = RewriteRelation(node.Right);
_semiJoinContextFlagStack.Pop();
return(node.Update(node.JoinType, newLeft, newRight, node.Condition, node.Probe, node.PassthruPredicate));
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
if (node.Condition != null)
{
_recorder.Record(node.Condition);
}
if (node.PassthruPredicate != null)
{
_recorder.Record(node.PassthruPredicate);
}
if (node.Probe != null)
{
_recorder.Record(node.Probe);
}
return(base.RewriteJoinRelation(node));
}
private static bool NeedsRewriting(BoundJoinRelation node)
{
if (node.JoinType != BoundJoinType.FullOuter)
{
return(false);
}
if (SubqueryChecker.ContainsSubquery(node.Condition))
{
return(true);
}
var left = node.Left.GetOutputValues().ToImmutableArray();
var right = node.Right.GetOutputValues().ToImmutableArray();
var conjunctions = Expression.SplitConjunctions(node.Condition);
return(!conjunctions.Any(c => CanBeUsedForHashMatch(left, right, c)));
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
if (node.Condition != null && node.Probe == null)
{
BoundExpression pushedLeft = null;
BoundExpression pushedRight = null;
BoundExpression remainder = null;
foreach (var conjunction in Expression.SplitConjunctions(node.Condition))
{
if (AllowsLeftPushDown(node.JoinType) && !conjunction.DependsOnAny(node.Right.GetOutputValues()))
{
pushedLeft = Expression.And(pushedLeft, conjunction);
}
else if (AllowsRightPushDown(node.JoinType) && !conjunction.DependsOnAny(node.Left.GetOutputValues()))
{
pushedRight = Expression.And(pushedRight, conjunction);
}
else
{
remainder = Expression.And(remainder, conjunction);
}
}
var newLeft = pushedLeft == null
? node.Left
: new BoundFilterRelation(node.Left, pushedLeft);
var newRight = pushedRight == null
? node.Right
: new BoundFilterRelation(node.Right, pushedRight);
var newNode = node.Update(node.JoinType,
RewriteRelation(newLeft),
RewriteRelation(newRight),
remainder,
RewriteValueSlot(node.Probe),
RewriteExpression(node.PassthruPredicate));
return(newNode);
}
return(base.RewriteJoinRelation(node));
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
var op = GetLogicalOperator(node.JoinType);
if (op == null)
{
return(base.RewriteJoinRelation(node));
}
// The optimizer already made sure that left usually contains the bigger
// relations.
//
// For a hash match, the left side is the one we're indexing. Hence, it's
// beneficial to make sure the we use the smaller relation as the left side.
//
// Hence, we simply swap left and right. However, this transformation is
// only valid if it's an inner join -- for the other join types it would
// change the semantics of the join.
var swapLeftRight = op == BoundHashMatchOperator.Inner;
var left = RewriteRelation(swapLeftRight ? node.Right : node.Left);
var leftOutputs = left.GetOutputValues().ToImmutableArray();
var right = RewriteRelation(swapLeftRight ? node.Left : node.Right);
var rightOutputs = right.GetOutputValues().ToImmutableArray();
var equalPredicatesInfo = GetEqualPredicatesInfo(node.Condition, leftOutputs, rightOutputs);
if (equalPredicatesInfo.Predicates.Any())
{
var equalPredicate = equalPredicatesInfo.Predicates.First();
var otherPredicates = Expression.And(equalPredicatesInfo.Predicates.Skip(1).Select(p => p.Condition));
var remainder = Expression.And(equalPredicatesInfo.Remainder, otherPredicates);
return(new BoundHashMatchRelation(op.Value, left, right, equalPredicate.Left, equalPredicate.Right, remainder));
}
return(base.RewriteJoinRelation(node));
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
var left = RewriteRelation(node.Left);
var right = RewriteRelation(node.Right);
var rewrittenRight = RewriteConjunctions(right, node.Condition);
if (rewrittenRight != null)
{
// We might have residual subqueries that couldn't be
// converted to semi joins.
return(RewriteRelation(node.Update(node.JoinType, left, rewrittenRight, null, node.Probe, node.PassthruPredicate)));
}
// There were no subqueries that could be expressed as semi joins.
// However, there might still exist subqueries, so we need to visit
// the expression that will convert them to probing semi joins.
var condition = RewriteExpression(node.Condition);
var rightWithProbes = RewriteInputWithSubqueries(right);
return(node.Update(node.JoinType, left, rightWithProbes, condition, node.Probe, node.PassthruPredicate));
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
BoundRelation otherSide;
if (IsInstantiatedCommonTableExpression(node.Left))
{
otherSide = RewriteRelation(node.Right);
}
else if (IsInstantiatedCommonTableExpression(node.Right))
{
otherSide = RewriteRelation(node.Left);
}
else
{
return(base.RewriteJoinRelation(node));
}
Debug.Assert(node.JoinType == BoundJoinType.Inner);
return(node.Condition == null
? otherSide
: new BoundFilterRelation(otherSide, node.Condition));
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
// Extract relations and predicates
List <BoundRelation> relations;
List <BoundExpression> predicates;
ExtractRelationsAndPredicates(node, out relations, out predicates);
// Build a graph where the nodes are relations and edges are the predicates
// connecting them.
ICollection <JoinNode> nodes;
ICollection <JoinEdge> edges;
BuildGraph(relations, predicates, out nodes, out edges);
// Given the graph, compute a join order that uses the predicates.
var result = AssembleJoin(nodes, edges);
return(result);
}
private Iterator BuildJoin(BoundJoinRelation relation)
{
var left = BuildRelation(relation.Left);
_outerRowBufferAllocation = BuildRowBufferAllocation(relation.Left, left.RowBuffer);
var right = BuildRelation(relation.Right);
var combinedAllocation = BuildRowBufferAllocation(relation.Right, right.RowBuffer);
_outerRowBufferAllocation = _outerRowBufferAllocation.Parent;
var predicate = BuildPredicate(relation.Condition, true, combinedAllocation);
var passthruPredicate = BuildPredicate(relation.PassthruPredicate, false, combinedAllocation);
switch (relation.JoinType)
{
case BoundJoinType.Inner:
Debug.Assert(relation.Probe == null);
return(new InnerNestedLoopsIterator(left, right, predicate, passthruPredicate));
case BoundJoinType.LeftSemi:
return(relation.Probe == null
? (Iterator) new LeftSemiNestedLoopsIterator(left, right, predicate, passthruPredicate)
: new ProbingLeftSemiNestedLoopsIterator(left, right, predicate));
case BoundJoinType.LeftAntiSemi:
Debug.Assert(relation.Probe == null);
return(new LeftAntiSemiNestedLoopsIterator(left, right, predicate, passthruPredicate));
case BoundJoinType.LeftOuter:
return(new LeftOuterNestedLoopsIterator(left, right, predicate, passthruPredicate));
default:
throw ExceptionBuilder.UnexpectedValue(relation.JoinType);
}
}
private BoundRelation MergeWithOrPushOverJoin(BoundFilterRelation node, BoundJoinRelation input)
{
// TODO: Right now, we're not pushing over a join if it has any probing.
//
// That might be too restristive. It should be OK to push a over
// a join to the side that isn't affecting the probe column.
//
// In other words:
//
// * pushing to the left is OK if it's a left (anti) semi join
// * pushing to the right is OK if it's a right (anti) semi join
if (input.Probe != null)
{
return(node.Update(RewriteRelation(input), node.Condition));
}
if (AllowsMerge(input.JoinType))
{
var newCondition = Expression.And(input.Condition, node.Condition);
var newInput = input.Update(input.JoinType, input.Left, input.Right, newCondition, null, null);
return(RewriteRelation(newInput));
}
else
{
BoundExpression pushedLeft = null;
BoundExpression pushedRight = null;
BoundExpression remainder = null;
foreach (var conjunction in Expression.SplitConjunctions(node.Condition))
{
if (AllowsLeftPushOver(input.JoinType) && !conjunction.DependsOnAny(input.Right.GetOutputValues()))
{
pushedLeft = Expression.And(pushedLeft, conjunction);
}
else if (AllowsRightPushOver(input.JoinType) && !conjunction.DependsOnAny(input.Left.GetOutputValues()))
{
pushedRight = Expression.And(pushedRight, conjunction);
}
else
{
remainder = Expression.And(remainder, conjunction);
}
}
var newLeft = pushedLeft == null
? input.Left
: new BoundFilterRelation(input.Left, pushedLeft);
var newRight = pushedRight == null
? input.Right
: new BoundFilterRelation(input.Right, pushedRight);
var newInput = input.Update(input.JoinType,
RewriteRelation(newLeft),
RewriteRelation(newRight),
input.Condition,
RewriteValueSlot(input.Probe),
RewriteExpression(input.PassthruPredicate));
var newNode = remainder == null
? (BoundRelation)newInput
: node.Update(newInput, remainder);
return(newNode);
}
}
private BoundRelation InstantiateRecursiveCommonTableExpression(ImmutableArray <ValueSlot> outputValues, CommonTableExpressionSymbol symbol)
{
// TableSpoolPusher
// Concat
// Compute (Recursion := 0)
// <Anchor>
// Assert (Recursion <= 100)
// Inner Join
// Compute (Recursion := Recursion + 1)
// TableSpoolPopper
// Concat
// Filter <RecursiveJoinPredicate1>
// <RecursiveMember1>
// Filter <RecursiveJoinPredicate2>
// <RecursiveMember2>
var valueSlotFactory = outputValues.First().Factory;
// Create output values
var unionRecusionSlot = valueSlotFactory.CreateTemporary(typeof(int));
var concatValueSlots = outputValues.Add(unionRecusionSlot);
// Create anchor
var anchor = RewriteRelation(Instatiator.Instantiate(symbol.Anchor.Relation));
var anchorValues = anchor.GetOutputValues().ToImmutableArray();
var initRecursionSlot = valueSlotFactory.CreateTemporary(typeof(int));
var initRecursionDefinition = new BoundComputedValue(Expression.Literal(0), initRecursionSlot);
var initRecursion = new BoundComputeRelation(anchor, ImmutableArray.Create(initRecursionDefinition));
var initRecursionOutputs = anchorValues.Add(initRecursionSlot);
// Create TableSpoolPopper
var tableSpoolPopperSlots = initRecursionOutputs.Select(v => v.Duplicate()).ToImmutableArray();
var tableSpoolPopper = new BoundTableSpoolPopper(tableSpoolPopperSlots);
var anchorRecursionCounter = tableSpoolPopperSlots.Last();
var inc = Expression.Plus(Expression.Value(anchorRecursionCounter), Expression.Literal(1));
var incRecursionSlot = valueSlotFactory.CreateTemporary(typeof(int));
var incRecursionDefinition = new BoundComputedValue(inc, incRecursionSlot);
var incRecursion = new BoundComputeRelation(tableSpoolPopper, ImmutableArray.Create(incRecursionDefinition));
// Create recursive members
var recursiveRewriter = new CommonTableExpressionInstantiator(symbol);
var recursiveMembers = new List <BoundRelation>(symbol.RecursiveMembers.Length);
var recursiveMemberOutputs = new List <ImmutableArray <ValueSlot> >(symbol.RecursiveMembers.Length);
var anchorReferences = tableSpoolPopperSlots.RemoveAt(tableSpoolPopperSlots.Length - 1);
foreach (var recursiveMember in symbol.RecursiveMembers)
{
var recursivePrototype = recursiveMember.Relation;
var mapping = CreateRecursiveMemberInstanceValueSlotMapping(symbol, anchorReferences, recursivePrototype);
var recursiveInstance = Instatiator.Instantiate(recursivePrototype, mapping);
var recursiveRelation = recursiveRewriter.RewriteRelation(recursiveInstance);
var recursiveRelationOutputs = recursiveRelation.GetOutputValues().ToImmutableArray();
recursiveMembers.Add(recursiveRelation);
recursiveMemberOutputs.Add(recursiveRelationOutputs);
}
// Concatenate recursive members
var recursiveConcatValues = Enumerable
.Range(0, concatValueSlots.Length - 1)
.Select(i =>
{
var slot = valueSlotFactory.CreateTemporary(concatValueSlots[i].Type);
return(new BoundUnifiedValue(slot, recursiveMemberOutputs.Select(o => o[i])));
})
.ToImmutableArray();
var hasSingleRecursiveMember = recursiveMembers.Count == 1;
var recursiveConcat = hasSingleRecursiveMember ? recursiveMembers.Single() : new BoundConcatenationRelation(recursiveMembers, recursiveConcatValues);
var recursionOutputs = hasSingleRecursiveMember ? recursiveMemberOutputs.Single() : recursiveConcatValues.Select(u => u.ValueSlot).ToImmutableArray();
// Create inner join
var join = new BoundJoinRelation(BoundJoinType.Inner, incRecursion, recursiveConcat, null, null, null);
var joinOutputs = recursionOutputs.Add(incRecursionSlot);
var recursiveProjection = new BoundProjectRelation(join, joinOutputs);
// Create assert
var assertCondition = Expression.LessThan(Expression.Value(incRecursionSlot), Expression.Literal(100));
var assert = new BoundAssertRelation(recursiveProjection, assertCondition, Resources.MaximumRecursionLevelExceeded);
// Create top level concat
var concatValues = concatValueSlots.Select((v, i) =>
{
var slots = new[]
{
initRecursionOutputs[i],
joinOutputs[i]
};
return(new BoundUnifiedValue(v, slots));
});
var concatInputs = new BoundRelation[] { initRecursion, assert };
var concat = new BoundConcatenationRelation(concatInputs, concatValues);
var tableSpoolPusher = new BoundTableSpoolPusher(concat);
return(new BoundProjectRelation(tableSpoolPusher, concatValueSlots.Take(concatValueSlots.Length - 1)));
}
private static BoundRelation AssembleJoin(ICollection <JoinNode> nodes, ICollection <JoinEdge> edges)
{
var nodeComparer = Comparer <JoinNode> .Create(CompareNode);
var remainingNodes = new HashSet <JoinNode>(nodes);
var remainingEdges = new HashSet <JoinEdge>(edges);
var candidateNodes = new HashSet <JoinNode>();
BoundRelation result = null;
while (remainingNodes.Count > 0)
{
var start = remainingNodes.OrderBy(n => n, nodeComparer).First();
remainingNodes.Remove(start);
var relation = start.Relation;
candidateNodes.UnionWith(start.Edges.Select(e => e.Other(start)));
while (candidateNodes.Count > 0)
{
var usableEdges = candidateNodes.SelectMany(n => n.Edges)
.Where(e => remainingEdges.Contains(e))
.Where(n => !remainingNodes.Contains(n.Left) || !remainingNodes.Contains(n.Right))
.Where(e => e.Conditions.Any(IsRelation))
.ToImmutableArray();
if (!usableEdges.Any())
{
usableEdges = candidateNodes.SelectMany(n => n.Edges)
.Where(e => remainingEdges.Contains(e))
.Where(n => !remainingNodes.Contains(n.Left) || !remainingNodes.Contains(n.Right))
.ToImmutableArray();
}
var nextNode = usableEdges.SelectMany(e => new[] { e.Left, e.Right })
.Where(candidateNodes.Contains)
.OrderBy(n => n, nodeComparer)
.FirstOrDefault();
if (nextNode != null)
{
candidateNodes.Remove(nextNode);
candidateNodes.UnionWith(nextNode.Edges.Select(e => e.Other(nextNode)).Where(n => remainingNodes.Contains(n)));
var edge = usableEdges.First(e => !remainingNodes.Contains(e.Left) && e.Right == nextNode ||
!remainingNodes.Contains(e.Right) && e.Left == nextNode);
remainingNodes.Remove(nextNode);
remainingEdges.Remove(edge);
var left = relation;
var right = nextNode.Relation;
var condition = Expression.And(edge.Conditions);
relation = new BoundJoinRelation(BoundJoinType.Inner, left, right, condition, null, null);
}
}
result = result == null
? relation
: new BoundJoinRelation(BoundJoinType.Inner, result, relation, null, null, null);
}
Debug.Assert(remainingNodes.Count == 0, @"Found remaining nodes");
// Add filter for remaining predicates
var remainingPredicates = remainingEdges.SelectMany(e => e.Conditions);
var remainingCondition = Expression.And(remainingPredicates);
if (remainingCondition != null)
{
result = new BoundFilterRelation(result, remainingCondition);
}
return(result);
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
// Get declared tables of left and right
var leftDefinedValues = node.Left.GetDefinedValues().ToImmutableArray();
var rightDefinedValues = node.Right.GetDefinedValues().ToImmutableArray();
// Replace outer joins by left-/right-/inner joins
if (node.JoinType == BoundJoinType.RightOuter ||
node.JoinType == BoundJoinType.FullOuter)
{
if (IsAnyNullRejected(leftDefinedValues))
{
var newType = node.JoinType == BoundJoinType.RightOuter
? BoundJoinType.Inner
: BoundJoinType.LeftOuter;
node = node.Update(newType, node.Left, node.Right, node.Condition, node.Probe, node.PassthruPredicate);
}
}
if (node.JoinType == BoundJoinType.LeftOuter ||
node.JoinType == BoundJoinType.FullOuter)
{
if (IsAnyNullRejected(rightDefinedValues))
{
var newType = node.JoinType == BoundJoinType.LeftOuter
? BoundJoinType.Inner
: BoundJoinType.RightOuter;
node = node.Update(newType, node.Left, node.Right, node.Condition, node.Probe, node.PassthruPredicate);
}
}
// After converting an outer join to an inner one we can
// sometimes eliminate the whole join.
if (node.JoinType == BoundJoinType.Inner)
{
if (node.Left is BoundConstantRelation && !node.Left.GetDefinedValues().Any())
{
return(RewriteRelation(WrapWithFilter(node.Right, node.Condition)));
}
if (node.Right is BoundConstantRelation && !node.Right.GetDefinedValues().Any())
{
return(RewriteRelation(WrapWithFilter(node.Left, node.Condition)));
}
}
// Analyze AND-parts of Condition
if (node.JoinType != BoundJoinType.FullOuter)
{
var dependencyFinder = new ValueSlotDependencyFinder();
foreach (var conjunction in Expression.SplitConjunctions(node.Condition))
{
// Check if we can derive from this conjunction that a table it depends on
// is null-rejected.
dependencyFinder.ValueSlots.Clear();
dependencyFinder.VisitExpression(conjunction);
var slots = dependencyFinder.ValueSlots;
var nullRejectedSlots = slots.Where(v => NullRejection.IsRejectingNull(conjunction, v));
foreach (var valueSlot in nullRejectedSlots)
{
if (node.JoinType != BoundJoinType.LeftOuter && leftDefinedValues.Contains(valueSlot))
{
AddNullRejectedTable(valueSlot);
}
else if (node.JoinType != BoundJoinType.RightOuter && rightDefinedValues.Contains(valueSlot))
{
AddNullRejectedTable(valueSlot);
}
}
}
}
// Visit children
return(base.RewriteJoinRelation(node));
}
private static CardinalityEstimate EstimateJoinRelation(BoundJoinRelation relation)
{
return(CardinalityEstimate.Unknown);
}
protected override BoundRelation RewriteJoinRelation(BoundJoinRelation node)
{
// First, let's rewrite our inputs
node = (BoundJoinRelation)base.RewriteJoinRelation(node);
// Get defined values of left and right
var leftDefinedValues = new HashSet <ValueSlot>(node.Left.GetDefinedValues());
var rightDefinedValues = new HashSet <ValueSlot>(node.Right.GetDefinedValues());
var extractedConjunctions = new List <BoundExpression>();
// Try to pull up conjunctions 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.JoinType != BoundJoinType.LeftOuter &&
node.JoinType != BoundJoinType.FullOuter)
{
if (node.Left is BoundFilterRelation leftAsFilter)
{
var anythingExtracted = false;
var remainingConjunctions = new List <BoundExpression>();
foreach (var conjunction in Expression.SplitConjunctions(leftAsFilter.Condition))
{
if (!ConjunctionHasOuterReference(leftDefinedValues, conjunction))
{
remainingConjunctions.Add(conjunction);
}
else
{
anythingExtracted = true;
extractedConjunctions.Add(conjunction);
}
}
if (!anythingExtracted)
{
// We haven't extracted any conjunctions.
//
// In order to avoid creating new node, we just do nothing.
}
else
{
var newCondition = Expression.And(remainingConjunctions);
if (newCondition == null)
{
node = node.WithLeft(leftAsFilter.Input);
}
else
{
leftAsFilter = leftAsFilter.WithCondition(newCondition);
node = node.WithLeft(leftAsFilter);
}
}
}
}
// Try to pull up conjunctions 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.JoinType != BoundJoinType.RightOuter &&
node.JoinType != BoundJoinType.FullOuter)
{
if (node.Right is BoundFilterRelation rightAsFilter)
{
var anythingExtracted = false;
var remainingConjunctions = new List <BoundExpression>();
foreach (var conjunction in Expression.SplitConjunctions(rightAsFilter.Condition))
{
if (!ConjunctionHasOuterReference(rightDefinedValues, conjunction))
{
remainingConjunctions.Add(conjunction);
}
else
{
anythingExtracted = true;
extractedConjunctions.Add(conjunction);
}
}
if (!anythingExtracted)
{
// We haven't extracted any conjunctions.
//
// In order to avoid creating new node, we just do nothing.
}
else
{
var newCondition = Expression.And(remainingConjunctions);
if (newCondition == null)
{
node = node.WithRight(rightAsFilter.Input);
}
else
{
rightAsFilter = rightAsFilter.WithCondition(newCondition);
node = node.WithRight(rightAsFilter);
}
}
}
}
// If we found any conjunctions that could be pulled up, merge them with the join predicate.
if (extractedConjunctions.Any())
{
var newCondition = Expression.And(new[] { node.Condition }.Concat(extractedConjunctions));
node = node.WithCondition(newCondition);
}
// Now we try to extract conjunctions 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 conjunction does not reference any
// columns from the side that is used as filter criteria (i.e. for LSJ this is the
// right side, for RSJ this is the left side).
if (node.JoinType != BoundJoinType.LeftOuter &&
node.JoinType != BoundJoinType.RightOuter &&
node.JoinType != BoundJoinType.FullOuter &&
node.Condition != null)
{
var conjunctionsAboveJoin = new List <BoundExpression>();
var remainingConjunctions = new List <BoundExpression>();
var definedValues = new HashSet <ValueSlot>(leftDefinedValues.Concat(rightDefinedValues));
foreach (var conjunction in Expression.SplitConjunctions(node.Condition))
{
if (ConjunctionHasOuterReference(definedValues, conjunction) && SemiJoinDoesNotDependOn(node.JoinType, conjunction, rightDefinedValues))
{
conjunctionsAboveJoin.Add(conjunction);
}
else
{
remainingConjunctions.Add(conjunction);
}
}
if (conjunctionsAboveJoin.Any())
{
var newCondition = Expression.And(remainingConjunctions);
node = node.WithCondition(newCondition);
var filterCondition = Expression.And(conjunctionsAboveJoin);
var filter = new BoundFilterRelation(node, filterCondition);
return(filter);
}
}
return(node);
}
