/// <summary>
/// Get a full one height tree with joint edges and unmaterlized edges.
/// </summary>
/// <param name="graph"></param>
/// <param name="component"></param>
/// <returns></returns>
private OneHeightTree GetNodeUnits(ConnectedComponent graph, MatchComponent component)
{
var useOriginalEdge = new List <OneHeightTree>();
var useRevEdge = new List <OneHeightTree>();
// Return node deinfed in the outer context preferably
foreach (var node in graph.Nodes.Values.Where(n => n.IsFromOuterContext && !component.Nodes.Contains(n)))
{
var remainingEdges = node.Neighbors.Where(e => !component.EdgeMaterilizedDict.ContainsKey(e)).ToList();
if (component.UnmaterializedNodeMapping.ContainsKey(node) ||
remainingEdges.Any(e => component.Nodes.Contains(e.SinkNode)))
{
return(new OneHeightTree
{
TreeRoot = node,
Edges = remainingEdges
});
}
}
foreach (var node in graph.Nodes.Values.Where(n => !component.Nodes.Contains(n)))
{
var remainingEdges = node.Neighbors.Where(e => !component.EdgeMaterilizedDict.ContainsKey(e)).ToList();
if (component.UnmaterializedNodeMapping.ContainsKey(node))
{
useOriginalEdge.Add(new OneHeightTree
{
TreeRoot = node,
Edges = remainingEdges,
});
break;
}
if (remainingEdges.Any(e => component.Nodes.Contains(e.SinkNode)))
{
useRevEdge.Add(new OneHeightTree
{
TreeRoot = node,
Edges = remainingEdges
});
}
}
if (useOriginalEdge.Any())
{
return(useOriginalEdge[0]);
}
if (useRevEdge.Any())
{
return(useRevEdge[0]);
}
return(null);
}
/// <summary>
/// Get a full one height tree with joint edges and unmaterlized edges.
/// </summary>
/// <param name="graph"></param>
/// <param name="component"></param>
/// <returns></returns>
private OneHeightTree GetNodeUnits(ConnectedComponent graph, MatchComponent component)
{
foreach (MatchNode node in graph.Nodes.Values.Where(n => !component.Nodes.ContainsKey(n.NodeAlias)))
{
List <MatchEdge> remainingEdges = node.Neighbors.Where(e => !component.EdgeMaterilizedDict.ContainsKey(e)).ToList();
if (component.UnmaterializedNodeMapping.ContainsKey(node) ||
remainingEdges.Any(e => component.Nodes.ContainsKey(e.SinkNode.NodeAlias)))
{
return(new OneHeightTree
{
TreeRoot = node,
Edges = remainingEdges,
});
}
}
return(null);
}
// We firstly think every node are isolated, and we will find subgraphs later
internal string AddTable(WNamedTableReference table)
{
string alias = table.Alias.Value;
this.TableInputDependency[alias] = new HashSet <string>();
MatchNode matchNode = new MatchNode()
{
NodeAlias = alias,
Neighbors = new List <MatchEdge>(),
ReverseNeighbors = new List <MatchEdge>(),
DanglingEdges = new List <MatchEdge>(),
Predicates = new List <WBooleanExpression>(),
Properties = new HashSet <string>()
};
ConnectedComponent subgraph = new ConnectedComponent();
subgraph.Nodes[alias] = matchNode;
this.GraphPattern.ConnectedSubgraphs.Add(subgraph);
matchNode.Position = this.TableInputDependency.Count;
return(alias);
}
/// <summary>
/// Get a full one height tree with joint edges and unmaterlized edges,
/// returns a tuple whose first item is the one height tree and the second item
/// indicates whether the one height tree only joins with the component's materialized
/// node on its root.
/// </summary>
/// <param name="graph"></param>
/// <param name="component"></param>
/// <returns></returns>
private IEnumerable<Tuple<OneHeightTree, bool>> GetNodeUnits(ConnectedComponent graph, MatchComponent component)
{
var nodes = graph.Nodes;
foreach (var node in nodes.Values.Where(e => !graph.IsTailNode[e]))
{
var remainingEdges = node.Neighbors.Where(e => !component.EdgeMaterilizedDict.ContainsKey(e)).ToList();
// If there exists a component's edge pointing to the 1-heright tree's root
// or a 1-height tree's edge pointing to the component's node, then generates a valid
// 1-height tree with edges. Otherwise, if a node can be joint to component as a single
// split node with unmaterialized edges, generates a 1-height tree with a tag set to true.
if (component.UnmaterializedNodeMapping.ContainsKey(node) ||
remainingEdges.Any(e => component.Nodes.Contains(e.SinkNode)))
{
yield return new Tuple<OneHeightTree, bool>(new OneHeightTree
{
TreeRoot = node,
Edges = remainingEdges
}, false);
}
else if (remainingEdges.Count > 0 && component.MaterializedNodeSplitCount.Count > 1 &&
component.MaterializedNodeSplitCount.ContainsKey(node))
{
yield return new Tuple<OneHeightTree, bool>(new OneHeightTree
{
TreeRoot = node,
Edges = remainingEdges
}, true);
}
}
}
public abstract List <Tuple <MatchNode, MatchEdge, MatchNode, List <MatchEdge>, List <MatchEdge> > > GetOptimizedTraversalOrder2(ConnectedComponent subGraph);
// Greate the MatchGraph of this AggregationBlock. If some free nodes and free edges are connected, they are in the same ConnectedComponent
internal HashSet <string> CreateMatchGraph(WMatchClause matchClause)
{
HashSet <string> freeNodesAndEdges = new HashSet <string>();
Dictionary <string, MatchPath> pathCollection = new Dictionary <string, MatchPath>(StringComparer.OrdinalIgnoreCase);
Dictionary <string, MatchNode> nodeCollection = new Dictionary <string, MatchNode>(StringComparer.OrdinalIgnoreCase);
Dictionary <string, MatchEdge> edgeCollection = new Dictionary <string, MatchEdge>(StringComparer.OrdinalIgnoreCase);
Dictionary <string, ConnectedComponent> subgraphCollection = new Dictionary <string, ConnectedComponent>(StringComparer.OrdinalIgnoreCase);
// we use Disjoint-set data structure to determine whether tables are in the same component or not.
UnionFind unionFind = new UnionFind();
foreach (ConnectedComponent subgraph in this.GraphPattern.ConnectedSubgraphs)
{
foreach (KeyValuePair <string, MatchNode> pair in subgraph.Nodes)
{
nodeCollection.Add(pair.Key, pair.Value);
unionFind.Add(pair.Key);
}
}
if (matchClause != null)
{
foreach (WMatchPath path in matchClause.Paths)
{
int index = 0;
bool outOfBlock = false;
MatchEdge edgeToSrcNode = null;
for (int count = path.PathEdgeList.Count; index < count; ++index)
{
WSchemaObjectName currentNodeTableRef = path.PathEdgeList[index].Item1;
WEdgeColumnReferenceExpression currentEdgeColumnRef = path.PathEdgeList[index].Item2;
WSchemaObjectName nextNodeTableRef = index != count - 1
? path.PathEdgeList[index + 1].Item1
: path.Tail;
string currentNodeExposedName = currentNodeTableRef.BaseIdentifier.Value;
string edgeAlias = currentEdgeColumnRef.Alias;
string nextNodeExposedName = nextNodeTableRef != null ? nextNodeTableRef.BaseIdentifier.Value : null;
// Get the source node of a path
if (!nodeCollection.ContainsKey(currentNodeExposedName))
{
continue;
}
MatchNode srcNode = nodeCollection[currentNodeExposedName];
// Get the edge of a path, and set required attributes
// Because the sourceNode is relative, we need to construct new edges or paths
// But they need to share the same predicates and proerties
MatchEdge edgeFromSrcNode;
if (currentEdgeColumnRef.MinLength == 1 && currentEdgeColumnRef.MaxLength == 1)
{
if (!edgeCollection.ContainsKey(edgeAlias))
{
edgeCollection[edgeAlias] = new MatchEdge()
{
LinkAlias = edgeAlias,
SourceNode = srcNode,
EdgeType = currentEdgeColumnRef.EdgeType,
Predicates = new List <WBooleanExpression>(),
BindNodeTableObjName = new WSchemaObjectName(),
IsReversed = false,
Properties = new List <string>(GraphViewReservedProperties.ReservedEdgeProperties)
};
unionFind.Add(edgeAlias);
}
edgeFromSrcNode = new MatchEdge
{
LinkAlias = edgeAlias,
SourceNode = srcNode,
EdgeType = edgeCollection[edgeAlias].EdgeType,
Predicates = edgeCollection[edgeAlias].Predicates,
BindNodeTableObjName = edgeCollection[edgeAlias].BindNodeTableObjName,
IsReversed = false,
Properties = edgeCollection[edgeAlias].Properties
};
}
else
{
if (!pathCollection.ContainsKey(edgeAlias))
{
pathCollection[edgeAlias] = new MatchPath
{
SourceNode = srcNode,
LinkAlias = edgeAlias,
Predicates = new List <WBooleanExpression>(),
BindNodeTableObjName = new WSchemaObjectName(),
MinLength = currentEdgeColumnRef.MinLength,
MaxLength = currentEdgeColumnRef.MaxLength,
ReferencePathInfo = false,
AttributeValueDict = currentEdgeColumnRef.AttributeValueDict,
IsReversed = false,
EdgeType = currentEdgeColumnRef.EdgeType,
Properties = new List <string>(GraphViewReservedProperties.ReservedEdgeProperties)
};
}
edgeFromSrcNode = new MatchPath
{
SourceNode = srcNode,
LinkAlias = edgeAlias,
Predicates = pathCollection[edgeAlias].Predicates,
BindNodeTableObjName = pathCollection[edgeAlias].BindNodeTableObjName,
MinLength = pathCollection[edgeAlias].MinLength,
MaxLength = pathCollection[edgeAlias].MaxLength,
ReferencePathInfo = false,
AttributeValueDict = pathCollection[edgeAlias].AttributeValueDict,
IsReversed = false,
EdgeType = pathCollection[edgeAlias].EdgeType,
Properties = pathCollection[edgeAlias].Properties
};
}
if (path.IsReversed)
{
unionFind.Union(edgeAlias, currentNodeExposedName);
}
else
{
unionFind.Union(currentNodeExposedName, edgeAlias);
}
if (edgeToSrcNode != null)
{
edgeToSrcNode.SinkNode = srcNode;
if (!(edgeToSrcNode is MatchPath))
{
// Construct reverse edge
MatchEdge reverseEdge = new MatchEdge
{
SourceNode = edgeToSrcNode.SinkNode,
SinkNode = edgeToSrcNode.SourceNode,
LinkAlias = edgeToSrcNode.LinkAlias,
Predicates = edgeToSrcNode.Predicates,
BindNodeTableObjName = edgeToSrcNode.BindNodeTableObjName,
IsReversed = true,
EdgeType = edgeToSrcNode.EdgeType,
Properties = edgeToSrcNode.Properties,
};
srcNode.ReverseNeighbors.Add(reverseEdge);
}
}
edgeToSrcNode = edgeFromSrcNode;
// Add this edge to node's neightbors
if (nextNodeExposedName != null)
{
if (path.IsReversed)
{
unionFind.Union(nextNodeExposedName, edgeAlias);
}
else
{
unionFind.Union(edgeAlias, nextNodeExposedName);
}
srcNode.Neighbors.Add(edgeFromSrcNode);
}
// Add this edge to node's dangling edges
else
{
srcNode.DanglingEdges.Add(edgeFromSrcNode);
}
}
if (path.Tail == null)
{
continue;
}
// Get destination node of a path
string tailExposedName = path.Tail.BaseIdentifier.Value;
if (!nodeCollection.ContainsKey(tailExposedName))
{
continue;
}
MatchNode destNode = nodeCollection[tailExposedName];
if (edgeToSrcNode != null)
{
edgeToSrcNode.SinkNode = destNode;
if (!(edgeToSrcNode is MatchPath))
{
// Construct reverse edge
MatchEdge reverseEdge = new MatchEdge
{
SourceNode = edgeToSrcNode.SinkNode,
SinkNode = edgeToSrcNode.SourceNode,
LinkAlias = edgeToSrcNode.LinkAlias,
Predicates = edgeToSrcNode.Predicates,
BindNodeTableObjName = edgeToSrcNode.BindNodeTableObjName,
IsReversed = true,
EdgeType = edgeToSrcNode.EdgeType,
Properties = edgeToSrcNode.Properties,
};
destNode.ReverseNeighbors.Add(reverseEdge);
}
}
}
}
// Use union find algorithmn to define which subgraph does a node belong to and put it into where it belongs to.
foreach (var node in nodeCollection)
{
freeNodesAndEdges.Add(node.Key);
string root = unionFind.Find(node.Key);
ConnectedComponent subGraph;
if (!subgraphCollection.ContainsKey(root))
{
subGraph = new ConnectedComponent();
subgraphCollection[root] = subGraph;
}
else
{
subGraph = subgraphCollection[root];
}
subGraph.Nodes[node.Key] = node.Value;
subGraph.IsTailNode[node.Value] = false;
foreach (MatchEdge edge in node.Value.Neighbors)
{
subGraph.Edges[edge.LinkAlias] = edge;
freeNodesAndEdges.Add(edge.LinkAlias);
}
foreach (MatchEdge edge in node.Value.DanglingEdges)
{
subGraph.Edges[edge.LinkAlias] = edge;
edge.IsDanglingEdge = true;
freeNodesAndEdges.Add(edge.LinkAlias);
}
if (node.Value.Neighbors.Count + node.Value.ReverseNeighbors.Count + node.Value.DanglingEdges.Count > 0)
{
node.Value.Properties.Add(GremlinKeyword.Star);
}
}
this.GraphPattern = new MatchGraph(subgraphCollection.Values.ToList());
return(freeNodesAndEdges);
}
/// <summary>
/// Constructs the graph pattern specified by the MATCH clause.
/// The graph pattern may consist of multiple fully-connected sub-graphs.
/// </summary>
/// <param name="query">The SELECT query block</param>
/// <returns>A graph object contains all the connected componeents</returns>
private MatchGraph ConstructGraph(WSelectQueryBlock query)
{
if (query == null || query.MatchClause == null)
return null;
var columnsOfNodeTables = _graphMetaData.ColumnsOfNodeTables;
var nodeViewMapping = _graphMetaData.NodeViewMapping;
var unionFind = new UnionFind();
var edgeColumnToAliasesDict = new Dictionary<string, List<string>>(StringComparer.OrdinalIgnoreCase);
var pathDictionary = new Dictionary<string, MatchPath>(StringComparer.OrdinalIgnoreCase);
var reversedEdgeDict = new Dictionary<string, MatchEdge>();
var matchClause = query.MatchClause;
var nodes = new Dictionary<string, MatchNode>(StringComparer.OrdinalIgnoreCase);
var connectedSubGraphs = new List<ConnectedComponent>();
var subGrpahMap = new Dictionary<string, ConnectedComponent>(StringComparer.OrdinalIgnoreCase);
var parent = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
unionFind.Parent = parent;
// Constructs the graph pattern specified by the path expressions in the MATCH clause
foreach (var path in matchClause.Paths)
{
var index = 0;
MatchEdge preEdge = null;
for (var count = path.PathEdgeList.Count; index < count; ++index)
{
var currentNodeTableRef = path.PathEdgeList[index].Item1;
var currentEdgeColumnRef = path.PathEdgeList[index].Item2;
var currentNodeExposedName = currentNodeTableRef.BaseIdentifier.Value;
var nextNodeTableRef = index != count - 1
? path.PathEdgeList[index + 1].Item1
: path.Tail;
var nextNodeExposedName = nextNodeTableRef.BaseIdentifier.Value;
var patternNode = nodes.GetOrCreate(currentNodeExposedName);
if (patternNode.NodeAlias == null)
{
patternNode.NodeAlias = currentNodeExposedName;
patternNode.Neighbors = new List<MatchEdge>();
patternNode.External = false;
var nodeTable = _context[currentNodeExposedName] as WNamedTableReference;
if (nodeTable != null)
{
patternNode.NodeTableObjectName = nodeTable.TableObjectName;
if (patternNode.NodeTableObjectName.SchemaIdentifier == null)
patternNode.NodeTableObjectName.Identifiers.Insert(0, new Identifier {Value = "dbo"});
}
}
Identifier edgeIdentifier = currentEdgeColumnRef.MultiPartIdentifier.Identifiers.Last();
string schema = patternNode.NodeTableObjectName.SchemaIdentifier.Value.ToLower();
string nodeTableName = patternNode.NodeTableObjectName.BaseIdentifier.Value;
string bindTableName =
_context.EdgeNodeBinding[
new Tuple<string, string>(nodeTableName.ToLower(), edgeIdentifier.Value.ToLower())].ToLower();
var bindNodeTableObjName = new WSchemaObjectName(
new Identifier {Value = schema},
new Identifier {Value = bindTableName}
);
var edgeColumn =
columnsOfNodeTables[
WNamedTableReference.SchemaNameToTuple(bindNodeTableObjName)][
currentEdgeColumnRef.MultiPartIdentifier.Identifiers.Last().Value];
string edgeAlias = currentEdgeColumnRef.Alias;
//string revEdgeAlias = edgeAlias;
bool isReversed = path.IsReversed || edgeColumn.EdgeInfo.IsReversedEdge;
string currentRevEdgeName = null;
// get original edge name
var currentEdgeName = currentEdgeColumnRef.MultiPartIdentifier.Identifiers.Last().Value;
var originalSourceName = isReversed ?
(_context[nextNodeExposedName] as WNamedTableReference).TableObjectName.BaseIdentifier.Value
: (_context[currentNodeExposedName] as WNamedTableReference).TableObjectName.BaseIdentifier.Value;
if (isReversed)
{
var i = currentEdgeName.IndexOf(originalSourceName, StringComparison.OrdinalIgnoreCase) +
originalSourceName.Length;
currentRevEdgeName = currentEdgeName.Substring(i + 1,
currentEdgeName.Length - "Reversed".Length - i - 1);
}
else
{
var srcTuple = WNamedTableReference.SchemaNameToTuple(patternNode.NodeTableObjectName);
// [nodeView]-[edge]->[node/nodeView]
if (edgeColumn.Role == WNodeTableColumnRole.Edge && nodeViewMapping.ContainsKey(srcTuple))
{
var physicalNodeName =
_context.EdgeNodeBinding[new Tuple<string, string>(srcTuple.Item2, currentEdgeName.ToLower())];
currentRevEdgeName = physicalNodeName + "_" + currentEdgeName + "Reversed";
}
else
{
currentRevEdgeName = originalSourceName + "_" + currentEdgeName + "Reversed";
}
}
if (edgeAlias == null)
{
edgeAlias = !isReversed
? string.Format("{0}_{1}_{2}", currentNodeExposedName, currentEdgeName, nextNodeExposedName)
: string.Format("{0}_{1}_{2}", nextNodeExposedName, currentRevEdgeName, currentNodeExposedName);
//when the current edge is a reversed edge, the key should still be the original edge name
//e.g.: TestDeleteEdgeWithTableAlias
var edgeNameKey = isReversed ? currentRevEdgeName : currentEdgeName;
if (edgeColumnToAliasesDict.ContainsKey(edgeNameKey))
{
edgeColumnToAliasesDict[edgeNameKey].Add(edgeAlias);
}
else
{
edgeColumnToAliasesDict.Add(edgeNameKey, new List<string> { edgeAlias });
}
}
MatchEdge edge, revEdge;
if (currentEdgeColumnRef.MinLength == 1 && currentEdgeColumnRef.MaxLength == 1)
{
var isEdgeView = edgeColumn.Role == WNodeTableColumnRole.EdgeView;
var hasRevEdge = edgeColumn.EdgeInfo.HasReversedEdge;
edge = new MatchEdge
{
IsEdgeView = isEdgeView,
IsReversedEdge = false,
HasReversedEdge = hasRevEdge,
SourceNode = patternNode,
EdgeColumn = currentEdgeColumnRef,
EdgeAlias = edgeAlias,
BindNodeTableObjName = bindNodeTableObjName,
};
_context.AddEdgeReference(edge);
if (hasRevEdge)
{
revEdge = new MatchEdge
{
IsEdgeView = isEdgeView,
IsReversedEdge = true,
SinkNode = patternNode,
EdgeColumn = new WEdgeColumnReferenceExpression()
{
ColumnType = currentEdgeColumnRef.ColumnType,
Alias = currentEdgeColumnRef.Alias,
MaxLength = currentEdgeColumnRef.MaxLength,
MinLength = currentEdgeColumnRef.MinLength,
AttributeValueDict = currentEdgeColumnRef.AttributeValueDict,
MultiPartIdentifier = new WMultiPartIdentifier(new Identifier()
{
QuoteType = currentEdgeColumnRef.MultiPartIdentifier.Identifiers.Last().QuoteType,
Value = currentRevEdgeName,
}),
},
EdgeAlias = edgeAlias,
//EdgeAlias = revEdgeAlias,
};
reversedEdgeDict[edge.EdgeAlias] = revEdge;
}
}
else
{
MatchPath matchPath = new MatchPath
{
SourceNode = patternNode,
EdgeColumn = currentEdgeColumnRef,
EdgeAlias = edgeAlias,
BindNodeTableObjName =
new WSchemaObjectName(
new Identifier {Value = schema},
new Identifier {Value = bindTableName}
),
MinLength = currentEdgeColumnRef.MinLength,
MaxLength = currentEdgeColumnRef.MaxLength,
ReferencePathInfo = false,
AttributeValueDict = currentEdgeColumnRef.AttributeValueDict
};
_context.AddEdgeReference(matchPath);
pathDictionary[edgeAlias] = matchPath;
edge = matchPath;
}
if (preEdge != null)
{
preEdge.SinkNode = patternNode;
if (preEdge.HasReversedEdge)
{
//var preSourceNode = preEdge.SourceNode;
var preEdgeBindNodeTableObjName = preEdge.BindNodeTableObjName;
var preEdgeColName = preEdge.EdgeColumn.MultiPartIdentifier.Identifiers.Last().Value;
var preEdgeColumn =
columnsOfNodeTables[
WNamedTableReference.SchemaNameToTuple(preEdgeBindNodeTableObjName)][
preEdgeColName];
var isEdgeView = preEdgeColumn.Role == WNodeTableColumnRole.EdgeView;
var isNodeView =
_graphMetaData.NodeViewMapping.ContainsKey(
WNamedTableReference.SchemaNameToTuple(patternNode.NodeTableObjectName));
reversedEdgeDict[preEdge.EdgeAlias].SourceNode = patternNode;
// [node/nodeView]-[edgeView]->[node/nodeView]
if (isEdgeView)
{
reversedEdgeDict[preEdge.EdgeAlias].BindNodeTableObjName = preEdgeBindNodeTableObjName;
}
// [node/nodeView]-[edge]->[nodeView]
else if (!isEdgeView && isNodeView)
{
reversedEdgeDict[preEdge.EdgeAlias].BindNodeTableObjName = new WSchemaObjectName(
new Identifier { Value = "dbo" },
new Identifier { Value = preEdgeColumn.EdgeInfo.SinkNodes.First() }
);
}
else
{
reversedEdgeDict[preEdge.EdgeAlias].BindNodeTableObjName = new WSchemaObjectName(
new Identifier { Value = schema },
new Identifier { Value = bindTableName }
);
}
}
}
preEdge = edge;
if (!parent.ContainsKey(currentNodeExposedName))
parent[currentNodeExposedName] = currentNodeExposedName;
if (!parent.ContainsKey(nextNodeExposedName))
parent[nextNodeExposedName] = nextNodeExposedName;
unionFind.Union(currentNodeExposedName, nextNodeExposedName);
patternNode.Neighbors.Add(edge);
}
var tailExposedName = path.Tail.BaseIdentifier.Value;
var tailNode = nodes.GetOrCreate(tailExposedName);
if (tailNode.NodeAlias == null)
{
tailNode.NodeAlias = tailExposedName;
tailNode.Neighbors = new List<MatchEdge>();
var nodeTable = _context[tailExposedName] as WNamedTableReference;
if (nodeTable != null)
{
tailNode.NodeTableObjectName = nodeTable.TableObjectName;
if (tailNode.NodeTableObjectName.SchemaIdentifier == null)
tailNode.NodeTableObjectName.Identifiers.Insert(0, new Identifier {Value = "dbo"});
}
}
if (preEdge != null)
{
preEdge.SinkNode = tailNode;
if (preEdge.HasReversedEdge)
{
var schema = tailNode.NodeTableObjectName.SchemaIdentifier.Value.ToLower();
var nodeTableName = tailNode.NodeTableObjectName.BaseIdentifier.Value;
//var preSourceNode = preEdge.SourceNode;
var preEdgeBindNodeTableObjName = preEdge.BindNodeTableObjName;
var preEdgeColName = preEdge.EdgeColumn.MultiPartIdentifier.Identifiers.Last().Value;
var preEdgeColumn =
columnsOfNodeTables[
WNamedTableReference.SchemaNameToTuple(preEdgeBindNodeTableObjName)][
preEdgeColName];
var isEdgeView = preEdgeColumn.Role == WNodeTableColumnRole.EdgeView;
var isNodeView =
_graphMetaData.NodeViewMapping.ContainsKey(
WNamedTableReference.SchemaNameToTuple(tailNode.NodeTableObjectName));
reversedEdgeDict[preEdge.EdgeAlias].SourceNode = tailNode;
// [node/nodeView]-[edgeView]->[node/nodeView]
if (isEdgeView)
{
reversedEdgeDict[preEdge.EdgeAlias].BindNodeTableObjName = preEdgeBindNodeTableObjName;
}
// [node/nodeView]-[edge]->[nodeView]
else if (!isEdgeView && isNodeView)
{
reversedEdgeDict[preEdge.EdgeAlias].BindNodeTableObjName = new WSchemaObjectName(
new Identifier { Value = "dbo" },
new Identifier { Value = preEdgeColumn.EdgeInfo.SinkNodes.First() }
);
}
else
{
reversedEdgeDict[preEdge.EdgeAlias].BindNodeTableObjName = new WSchemaObjectName(
new Identifier { Value = schema },
new Identifier { Value = nodeTableName.ToLower() }
);
}
}
}
}
// Puts nodes into subgraphs
foreach (var node in nodes)
{
string root = unionFind.Find(node.Key);
if (!subGrpahMap.ContainsKey(root))
{
var subGraph = new ConnectedComponent();
subGraph.Nodes[node.Key] = node.Value;
foreach (var edge in node.Value.Neighbors)
{
subGraph.Edges[edge.EdgeAlias] = edge;
}
subGrpahMap[root] = subGraph;
connectedSubGraphs.Add(subGraph);
subGraph.IsTailNode[node.Value] = false;
}
else
{
var subGraph = subGrpahMap[root];
subGraph.Nodes[node.Key] = node.Value;
foreach (var edge in node.Value.Neighbors)
{
subGraph.Edges[edge.EdgeAlias] = edge;
}
subGraph.IsTailNode[node.Value] = false;
}
}
var graph = new MatchGraph
{
ReversedEdgeDict = reversedEdgeDict,
ConnectedSubGraphs = connectedSubGraphs,
SourceNodeStatisticsDict = new Dictionary<Tuple<string, bool>, Statistics>(),
};
unionFind.Parent = null;
// When an edge in the MATCH clause is not associated with an alias,
// assigns to it a default alias: sourceAlias_EdgeColumnName_sinkAlias.
// Also rewrites edge attributes anywhere in the query that can be bound to this default alias.
var replaceTableRefVisitor = new ReplaceEdgeReferenceVisitor();
replaceTableRefVisitor.Invoke(query, edgeColumnToAliasesDict);
// Rematerializes node tables in the MATCH clause which are defined in the upper-level context
// and join them with the upper-level table references.
RematerilizeExtrenalNodeTableReference(query, nodes);
// Transforms the path reference in the SELECT elements into a
// scalar function to display path information.
TransformPathInfoDisplaySelectElement(query, pathDictionary);
return graph;
}
public abstract List <Tuple <MatchNode, MatchEdge> > GetOptimizedTraversalOrder(ConnectedComponent subGraph, out Dictionary <string, List <Tuple <MatchEdge, MaterializedEdgeType> > > nodeToMaterializedEdgesDict);
/// <summary>
/// Get a full one height tree with joint edges and unmaterlized edges,
/// returns a tuple whose first item is the one height tree and the second item
/// indicates whether the one height tree only joins with the component's materialized
/// node on its root.
/// </summary>
/// <param name="graph"></param>
/// <param name="component"></param>
/// <returns></returns>
private IEnumerable<OneHeightTree> GetNodeUnits(ConnectedComponent graph, MatchComponent component)
{
//var nodes = graph.Nodes;
//foreach (var node in graph.Nodes.Values)
foreach (var node in graph.Nodes.Values.Where(n => !component.Nodes.Contains(n)))
{
var remainingEdges = node.Neighbors.Where(e => !component.EdgeMaterilizedDict.ContainsKey(e)).ToList();
if (component.UnmaterializedNodeMapping.ContainsKey(node) ||
remainingEdges.Any(e => component.Nodes.Contains(e.SinkNode)))
{
yield return new OneHeightTree
{
TreeRoot = node,
Edges = remainingEdges
};
}
}
}
/// <summary>
/// Get the optimal join component for the given connected graph
/// 1. Generate the initial states
/// 2. DP, Iterate on each states:
/// Get smallest join units -> Enumerate on all possible combination of the join units
/// -> Join to the current component to get the next states
/// -> Those components with the largest average size per edge will be eliminate if exceeding the upper bound
/// 3. If all the components has reached its end states, return the component with the smallest join cost
/// </summary>
/// <param name="subGraph"></param>
/// <param name="revEdgeDict"></param>
/// <param name="srcNodeStatisticsDict"></param>
/// <returns></returns>
private MatchComponent ConstructComponent(ConnectedComponent subGraph, Dictionary<string, MatchEdge> revEdgeDict,
Dictionary<Tuple<string, bool>, Statistics> srcNodeStatisticsDict)
{
//var componentStates = new List<MatchComponent>();
MatchComponent optimalFinalComponent = null;
//Init
double maxValue = Double.MinValue;
var componentStates = subGraph.Nodes.Select(node => new MatchComponent(node.Value)).ToList();
// DP
while (componentStates.Any())
{
int maxIndex = -1;
var nextCompnentStates = new List<MatchComponent>();
// Iterate on current components
foreach (var curComponent in componentStates)
{
var nodeUnits = GetNodeUnits(subGraph, curComponent);
if (!nodeUnits.Any()
&& curComponent.ActiveNodeCount == subGraph.ActiveNodeCount
&& curComponent.EdgeMaterilizedDict.Count(e => e.Value == true) == subGraph.EdgeCount
)
{
if (optimalFinalComponent == null || curComponent.Cost < optimalFinalComponent.Cost)
{
optimalFinalComponent = curComponent;
}
continue;
}
var candidateUnits = _pruningStrategy.GetCandidateUnits(nodeUnits, curComponent, revEdgeDict);
// Iterates on the candidate node units & add it to the current component to generate next states
foreach (var candidateUnit in candidateUnits)
{
// Pre-filter. If the lower bound of the current totoal join cost
// > current optimal join cost, prunes this component.
if (optimalFinalComponent != null)
{
double candidateSize = candidateUnit.TreeRoot.EstimatedRows*
candidateUnit.PreMatOutgoingEdges.Select(e => e.AverageDegree)
.Aggregate(1.0, (cur, next) => cur*next)*
candidateUnit.PostMatOutgoingEdges.Select(e => e.AverageDegree)
.Aggregate(1.0, (cur, next) => cur*next)*
candidateUnit.UnmaterializedEdges.Select(e => e.AverageDegree)
.Aggregate(1.0, (cur, next) => cur*next);
double costLowerBound = curComponent.Cardinality*
candidateUnit.PreMatIncomingEdges.Select(e => e.AverageDegree)
.Aggregate(1.0, (cur, next) => cur * next)
+ candidateSize;
if (candidateUnit.JoinHint == JoinHint.Loop)
costLowerBound = Math.Min(costLowerBound,
Math.Log(candidateUnit.TreeRoot.EstimatedRows, 512));
if (curComponent.Cost + costLowerBound >
optimalFinalComponent.Cost )
{
continue;
}
}
var newComponent = curComponent.GetNextState(candidateUnit, _statisticsCalculator, _graphMetaData, srcNodeStatisticsDict);
if (nextCompnentStates.Count >= MaxStates)
{
if (maxIndex < 0)
{
var tuple = GetMostExpensiveMatchComponent(nextCompnentStates);
maxIndex = tuple.Item1;
maxValue = tuple.Item2;
}
else
{
int compEdgeCount = newComponent.EdgeMaterilizedDict.Count;
compEdgeCount = compEdgeCount == 0 ? 1 : compEdgeCount;
if (newComponent.Cost/compEdgeCount < maxValue)
{
nextCompnentStates[maxIndex] = newComponent;
var tuple = GetMostExpensiveMatchComponent(nextCompnentStates);
maxIndex = tuple.Item1;
maxValue = tuple.Item2;
}
continue;
}
}
nextCompnentStates.Add(newComponent);
}
}
componentStates = nextCompnentStates;
}
return optimalFinalComponent;
}
/// <summary>
/// Get the optimal join component for the given connected graph
/// 1. Generate the initial states
/// 2. DP, Iterate on each states:
/// Get smallest join units -> Enumerate on all possible combination of the join units
/// -> Join to the current component to get the next states
/// -> Those components with the largest average size per edge will be eliminate if exceeding the upper bound
/// 3. If all the components has reached its end states, return the component with the smallest join cost
/// </summary>
/// <param name="subGraph"></param>
/// <returns></returns>
private MatchComponent ConstructComponent(ConnectedComponent subGraph)
{
var componentStates = new List<MatchComponent>();
MatchComponent optimalFinalComponent = null;
//Init
double maxValue = Double.MinValue;
foreach (var node in subGraph.Nodes)
{
if (!subGraph.IsTailNode[node.Value])
{
// Enumerate on each edge for a node to generate the intial states
var nodeEdgeCount = node.Value.Neighbors.Count;
int eNum = (int) Math.Pow(2, nodeEdgeCount) - 1;
while (eNum > 0)
{
var nodeInitialEdges = new List<MatchEdge>();
for (int i = 0; i < nodeEdgeCount; i++)
{
int index = (1 << i);
if ((eNum & index) != 0)
{
nodeInitialEdges.Add(node.Value.Neighbors[i]);
}
}
componentStates.Add(new MatchComponent(node.Value, nodeInitialEdges, _graphMetaData));
eNum--;
}
}
}
// DP
while (componentStates.Any())
{
int maxIndex = -1;
var nextCompnentStates = new List<MatchComponent>();
// Iterate on current components
foreach (var curComponent in componentStates)
{
var nodeUnits = GetNodeUnits(subGraph, curComponent);
if (!nodeUnits.Any()
&& curComponent.ActiveNodeCount == subGraph.ActiveNodeCount
&& curComponent.EdgeMaterilizedDict.Count == subGraph.EdgeCount
)
{
if (optimalFinalComponent == null || curComponent.Cost < optimalFinalComponent.Cost)
{
optimalFinalComponent = curComponent;
}
continue;
}
var candidateUnits = _pruningStrategy.GetCandidateUnits(nodeUnits, curComponent);
// Iterates on the candidate node units & add it to the current component to generate next states
foreach (var candidateUnit in candidateUnits)
{
// Pre-filter. If the lower bound of the current totoal join cost
// > current optimal join cost, prunes this component.
if (optimalFinalComponent != null)
{
double candidateSize = candidateUnit.TreeRoot.EstimatedRows*
candidateUnit.UnmaterializedEdges.Select(e => e.AverageDegree)
.Aggregate(1.0, (cur, next) => cur*next)*
candidateUnit.MaterializedEdges.Select(e => e.AverageDegree)
.Aggregate(1.0, (cur, next) => cur*next);
double costLowerBound = curComponent.Cardinality + candidateSize;
if (candidateUnit.MaterializedEdges.Count == 0)
costLowerBound = Math.Min(costLowerBound,
Math.Log(candidateUnit.TreeRoot.EstimatedRows, 512));
if (curComponent.Cost + costLowerBound >
optimalFinalComponent.Cost )
{
continue;
}
}
var newComponent = curComponent.GetNextState(candidateUnit, _statisticsCalculator,_graphMetaData);
if (nextCompnentStates.Count >= MaxStates)
{
if (maxIndex < 0)
{
var tuple = GetMostExpensiveMatchComponent(nextCompnentStates);
maxIndex = tuple.Item1;
maxValue = tuple.Item2;
}
else
{
int compEdgeCount = newComponent.EdgeMaterilizedDict.Count;
compEdgeCount = compEdgeCount == 0 ? 1 : compEdgeCount;
if (newComponent.Cost/compEdgeCount < maxValue)
{
nextCompnentStates[maxIndex] = newComponent;
var tuple = GetMostExpensiveMatchComponent(nextCompnentStates);
maxIndex = tuple.Item1;
maxValue = tuple.Item2;
}
continue;
}
}
nextCompnentStates.Add(newComponent);
}
}
componentStates = nextCompnentStates;
}
return optimalFinalComponent;
}
public override List <Tuple <MatchNode, MatchEdge> > GetOptimizedTraversalOrder(ConnectedComponent subGraph, out Dictionary <string, List <Tuple <MatchEdge, MaterializedEdgeType> > > nodeToMaterializedEdgesDict)
{
nodeToMaterializedEdgesDict = null;
if (subGraph.Nodes.Count == 1)
{
return
new List <Tuple <MatchNode, MatchEdge> >
{
new Tuple <MatchNode, MatchEdge>(subGraph.Nodes.First().Value, null),
}
}
;
// If it exists, pick a node defined in the outer context as the start point
var componentStates = subGraph.Nodes.Where(node => node.Value.IsFromOuterContext).
Select(node => new MatchComponent(node.Value)).Take(1).ToList();
// Else, pick a node without incoming edges as the start point
if (!componentStates.Any())
{
componentStates = subGraph.Nodes.Where(node => node.Value.ReverseNeighbors.Count == 0).
Select(node => new MatchComponent(node.Value)).Take(1).ToList();
}
// Otherwise, pick a node randomly as the start point
else if (!componentStates.Any())
{
componentStates.Add(new MatchComponent(subGraph.Nodes.First().Value));
}
// DP
while (componentStates.Any())
{
var nextCompnentStates = new List <MatchComponent>();
// Iterate on current components
foreach (var curComponent in componentStates)
{
var nodeUnits = GetNodeUnits(subGraph, curComponent);
if (nodeUnits == null &&
curComponent.ActiveNodeCount == subGraph.ActiveNodeCount &&
curComponent.EdgeMaterilizedDict.Count(e => e.Value == true) == subGraph.EdgeCount)
{
curComponent.TraversalChain.Reverse();
nodeToMaterializedEdgesDict = curComponent.NodeToMaterializedEdgesDict;
return(curComponent.TraversalChain);
}
var candidateUnit = GetCandidateUnits(nodeUnits, curComponent);
// Add it to the current component to generate next states
var newComponent = GetNextState(curComponent, candidateUnit);
if (nextCompnentStates.Count >= MaxStates)
{
throw new GraphViewException("This graph pattern is not supported yet.");
}
nextCompnentStates.Add(newComponent);
}
componentStates = nextCompnentStates;
}
return(null);
}
/// <summary>
/// Construct Graph from the match clause. The Graph can consist of multiple connected SubGraph.
/// Not supported in this version
/// </summary>
/// <param name="query"></param>
/// <returns></returns>
private MatchGraph ConstructGraph(WSelectQueryBlock query)
{
var unionFind = new UnionFind();
if (query.MatchClause == null)
return null;
var edgeTableReferenceDict = new Dictionary<string, List<string>>(StringComparer.CurrentCultureIgnoreCase);
var matchClause = query.MatchClause;
var nodes = new Dictionary<string, MatchNode>(StringComparer.CurrentCultureIgnoreCase);
var connectedSubGraphs = new List<ConnectedComponent>();
var subGrpahMap = new Dictionary<string, ConnectedComponent>(StringComparer.CurrentCultureIgnoreCase);
var parent = new Dictionary<string, string>(StringComparer.CurrentCultureIgnoreCase);
unionFind.Parent = parent;
HashSet<Tuple<string, string>> nodeTypes = new HashSet<Tuple<string, string>>();
//Construct Graph from Match Pattern
foreach (var path in matchClause.Paths)
{
var index = 0;
MatchEdge preEdge = null;
for (var count = path.PathNodeList.Count; index < count; ++index)
{
var currentNode = path.PathNodeList[index].Item1;
var currentEdge = path.PathNodeList[index].Item2;
var currentNodeExposedName = currentNode.BaseIdentifier.Value;
var nextNode = index != count - 1
? path.PathNodeList[index + 1].Item1
: path.Tail;
var nextNodeExposedName = nextNode.BaseIdentifier.Value;
var node = nodes.GetOrCreate(currentNodeExposedName);
if (node.NodeAlias == null)
{
node.NodeAlias = currentNodeExposedName;
node.Neighbors = new List<MatchEdge>();
node.External = false;
var nodeTable = _context[currentNodeExposedName] as WNamedTableReference;
if (nodeTable != null)
{
node.TableObjectName = nodeTable.TableObjectName;
if (node.TableObjectName.SchemaIdentifier == null)
node.TableObjectName.Identifiers.Insert(0, new Identifier { Value = "dbo" });
var nodeTypeTuple = WNamedTableReference.SchemaNameToTuple(node.TableObjectName);
if (!nodeTypes.Contains(nodeTypeTuple))
nodeTypes.Add(nodeTypeTuple);
}
}
if (currentEdge.AliasRole == AliasType.Default)
{
var currentEdgeName = currentEdge.MultiPartIdentifier.Identifiers.Last().Value;
if (edgeTableReferenceDict.ContainsKey(currentEdgeName))
{
edgeTableReferenceDict[currentEdgeName].Add(currentEdge.Alias);
}
else
{
edgeTableReferenceDict.Add(currentEdgeName, new List<string> { currentEdge.Alias });
}
}
var edge = new MatchEdge
{
SourceNode = node,
EdgeColumn = new WColumnReferenceExpression
{
MultiPartIdentifier = new WMultiPartIdentifier
{
Identifiers = new List<Identifier>
{
new Identifier {Value = node.NodeAlias},
currentEdge.MultiPartIdentifier.Identifiers.Last()
}
}
},
EdgeAlias = currentEdge.Alias
};
if (preEdge != null)
{
preEdge.SinkNode = node;
}
preEdge = edge;
if (!parent.ContainsKey(currentNodeExposedName))
parent[currentNodeExposedName] = currentNodeExposedName;
if (!parent.ContainsKey(nextNodeExposedName))
parent[nextNodeExposedName] = nextNodeExposedName;
unionFind.Union(currentNodeExposedName, nextNodeExposedName);
node.Neighbors.Add(edge);
_context.AddEdgeReference(currentEdge.Alias, edge.SourceNode.TableObjectName, currentEdge);
}
var tailExposedName = path.Tail.BaseIdentifier.Value;
var tailNode = nodes.GetOrCreate(tailExposedName);
if (tailNode.NodeAlias == null)
{
tailNode.NodeAlias = tailExposedName;
tailNode.Neighbors = new List<MatchEdge>();
var nodeTable = _context[tailExposedName] as WNamedTableReference;
if (nodeTable != null)
{
tailNode.TableObjectName = nodeTable.TableObjectName;
if (tailNode.TableObjectName.SchemaIdentifier == null)
tailNode.TableObjectName.Identifiers.Insert(0, new Identifier { Value = "dbo" });
var nodeTypeTuple = WNamedTableReference.SchemaNameToTuple(tailNode.TableObjectName);
if (!nodeTypes.Contains(nodeTypeTuple))
nodeTypes.Add(nodeTypeTuple);
}
}
if (preEdge != null)
preEdge.SinkNode = tailNode;
}
// Put nodes into subgraphs
foreach (var node in nodes)
{
string root = unionFind.Find(node.Key);
if (!subGrpahMap.ContainsKey(root))
{
var subGraph = new ConnectedComponent();
subGraph.Nodes[node.Key] = node.Value;
foreach (var edge in node.Value.Neighbors)
{
subGraph.Edges[edge.EdgeAlias] = edge;
}
subGrpahMap[root] = subGraph;
connectedSubGraphs.Add(subGraph);
subGraph.IsTailNode[node.Value] = false;
}
else
{
var subGraph = subGrpahMap[root];
subGraph.Nodes[node.Key] = node.Value;
foreach (var edge in node.Value.Neighbors)
{
subGraph.Edges[edge.EdgeAlias] = edge;
}
subGraph.IsTailNode[node.Value] = false;
}
}
// Replace Edge name alias with proper alias in the query
var replaceTableRefVisitor = new ReplaceTableRefVisitor();
replaceTableRefVisitor.Invoke(query, edgeTableReferenceDict);
// If a table alias in the MATCH clause is defined in an upper-level context,
// to be able to translate this MATCH clause, this table alias must be re-materialized
// in the FROM clause of the current context and joined with the corresponding table
// in the upper-level context.
var tableRefs = query.FromClause.TableReferences;
var tableSet = new HashSet<string>(StringComparer.CurrentCultureIgnoreCase);
var newTableRefs = new List<WTableReference>();
for (int index = 0; index < tableRefs.Count; ++index)
{
var table = tableRefs[index] as WNamedTableReference;
if (table == null)
{
newTableRefs.Add(tableRefs[index]);
continue;
}
var tableTuple = WNamedTableReference.SchemaNameToTuple(table.TableObjectName);
if (!nodeTypes.Contains(tableTuple))
{
newTableRefs.Add(table);
}
else
{
tableSet.Add(table.ExposedName.Value);
}
}
query.FromClause = new WFromClause
{
TableReferences = newTableRefs,
};
WBooleanExpression whereCondiction = null;
foreach (var node in nodes)
{
if (!tableSet.Contains(node.Key))
{
node.Value.External = true;
var newWhereCondition = new WBooleanComparisonExpression
{
ComparisonType = BooleanComparisonType.Equals,
FirstExpr = new WColumnReferenceExpression
{
MultiPartIdentifier = new WMultiPartIdentifier(
new Identifier { Value = node.Key },
new Identifier { Value = "GlobalNodeId" })
},
SecondExpr = new WColumnReferenceExpression
{
MultiPartIdentifier = new WMultiPartIdentifier(
new Identifier { Value = node.Value.RefAlias },
new Identifier { Value = "GlobalNodeId" })
},
};
whereCondiction = WBooleanBinaryExpression.Conjunction(whereCondiction, newWhereCondition);
}
}
if (whereCondiction != null)
{
if (query.WhereClause == null)
{
query.WhereClause = new WWhereClause { SearchCondition = whereCondiction };
}
else
{
if (query.WhereClause.SearchCondition == null)
{
query.WhereClause.SearchCondition = whereCondiction;
}
else
{
query.WhereClause.SearchCondition = new WBooleanBinaryExpression
{
BooleanExpressionType = BooleanBinaryExpressionType.And,
FirstExpr = new WBooleanParenthesisExpression
{
Expression = query.WhereClause.SearchCondition
},
SecondExpr = new WBooleanParenthesisExpression
{
Expression = whereCondiction
}
};
}
}
}
var graph = new MatchGraph
{
ConnectedSubGraphs = connectedSubGraphs,
NodeTypesSet = nodeTypes,
};
unionFind.Parent = null;
return graph;
}
/// <summary>
/// Get the optimal join component for the given connected graph
/// 1. Generate the initial states
/// 2. DP, Iterate on each states:
/// Get smallest join units -> Enumerate on all possible combination of the join units
/// -> Join to the current component to get the next states
/// -> Those components with the largest average size per edge will be eliminate if exceeding the upper bound
/// 3. If all the components has reached its end states, return the component with the smallest join cost
/// </summary>
/// <param name="subGraph"></param>
/// <returns></returns>
public MatchComponent ConstructComponent(ConnectedComponent subGraph)
{
var componentStates = new List<MatchComponent>();
var nodes = subGraph.Nodes;
var edges = subGraph.Edges;
int nodeCount = subGraph.IsTailNode.Count(e => !e.Value);
MatchComponent finishedComponent = null;
//Init
int maxIndex = -1;
double maxValue = Double.MinValue;
foreach (var node in nodes)
{
if (!subGraph.IsTailNode[node.Value])
{
// Enumerate on each edge for a node to generate the intial states
var edgeCount = node.Value.Neighbors.Count;
int eNum = (int) Math.Pow(2, edgeCount) - 1;
while (eNum > 0)
{
var nodeInitialEdges = new List<MatchEdge>();
for (int i = 0; i < edgeCount; i++)
{
int index = (1 << i);
if ((eNum & index) != 0)
{
nodeInitialEdges.Add(node.Value.Neighbors[i]);
}
}
componentStates.Add(new MatchComponent(node.Value, nodeInitialEdges, _context));
eNum--;
}
}
}
// DP
while (componentStates.Any())
{
maxIndex = -1;
var nextCompnentStates = new List<MatchComponent>();
// Iterate on current components
foreach (var curComponent in componentStates)
{
var nodeUnits = GetNodeUnits(subGraph, curComponent).ToList();
if (!nodeUnits.Any())
{
if (finishedComponent == null || curComponent.Cost < finishedComponent.Cost)
{
finishedComponent = curComponent;
}
continue;
}
var candidateUnits = _pruningStrategy.GetCandidateUnits(nodeUnits, curComponent);
// Iterate on the candidate node units & add it to the current component to generate next states
foreach (var candidateUnit in candidateUnits)
{
// Pre-filter
if (finishedComponent != null &&
(curComponent.Size +
candidateUnit.TreeRoot.EstimatedRows*
candidateUnit.UnmaterializedEdges.Select(e => e.AverageDegree)
.Aggregate(1.0, (cur, next) => cur*next)*
candidateUnit.MaterializedEdges.Select(e => e.AverageDegree)
.Aggregate(1.0, (cur, next) => cur*next) >
finishedComponent.Cost))
{
continue;
}
// TODO : redundant work if newSize>maxvalue
var newComponent = curComponent.GetNextState(candidateUnit, _tableIdDensity, _statisticsCalculator);
if (nextCompnentStates.Count >= MaxStates)
{
if (maxIndex < 0)
{
var tuple = GetMostExpensiveMatchComponent(nextCompnentStates);
maxIndex = tuple.Item1;
maxValue = tuple.Item2;
}
else
{
int edgeCount = newComponent.EdgeMaterilizedDict.Count;
edgeCount = edgeCount == 0 ? 1 : edgeCount;
if (newComponent.Cost / edgeCount < maxValue)
{
var temp = nextCompnentStates[maxIndex];
nextCompnentStates[maxIndex] = newComponent;
var tuple = GetMostExpensiveMatchComponent(nextCompnentStates);
maxIndex = tuple.Item1;
maxValue = tuple.Item2;
}
continue;
}
}
nextCompnentStates.Add(newComponent);
}
}
componentStates = nextCompnentStates;
}
return finishedComponent;
}
/// <summary>
/// Get a full one height tree with joint edges and unmaterlized edges,
/// returns a tuple whose first item is the one height tree and the second item
/// indicates whether the one height tree only joins with the component's materialized
/// node on its root.
/// </summary>
/// <param name="graph"></param>
/// <param name="component"></param>
/// <returns></returns>
public IEnumerable<Tuple<OneHeightTree,bool>> GetNodeUnits(ConnectedComponent graph, MatchComponent component)
{
var nodes = graph.Nodes;
foreach (var node in nodes.Values.Where(e => !graph.IsTailNode[e]))
{
//var newJoinUnitList = new List<MatchJoinUnit>()
bool joint = false;
var jointEdges = new List<MatchEdge>();
var nodeEdgeDict = node.Neighbors.ToDictionary(e => e,
e => component.EdgeMaterilizedDict.ContainsKey(e));
// Edge to component node
foreach (var edge in node.Neighbors.Where(e => !nodeEdgeDict[e]))
{
if (component.Nodes.Contains(edge.SinkNode))
{
joint = true;
nodeEdgeDict[edge] = true;
jointEdges.Add(edge);
}
}
// Component edge to node
if (!joint && component.UnmaterializedNodeMapping.ContainsKey(node))
{
joint = true;
}
// Add unpopulated edges
var nodeUnpopulatedEdges = nodeEdgeDict.Where(e => !e.Value).Select(e => e.Key).ToList();
if (joint)
yield return new Tuple<OneHeightTree, bool>(new OneHeightTree
{
TreeRoot = node,
MaterializedEdges = jointEdges,
UnmaterializedEdges = nodeUnpopulatedEdges,
}, false);
// Single node edge
else if (nodeUnpopulatedEdges.Count > 0 && component.MaterializedNodeSplitCount.Count > 1 && component.MaterializedNodeSplitCount.ContainsKey(node))
{
yield return new Tuple<OneHeightTree, bool>(new OneHeightTree
{
TreeRoot = node,
MaterializedEdges = jointEdges,
UnmaterializedEdges = nodeUnpopulatedEdges,
}, true);
}
}
}
/// <summary>
/// Constructs the graph pattern specified by the MATCH clause.
/// The graph pattern may consist of multiple fully-connected sub-graphs.
/// </summary>
/// <param name="query">The SELECT query block</param>
/// <returns>A graph object contains all the connected componeents</returns>
private MatchGraph ConstructGraph(WSelectQueryBlock query)
{
if (query == null || query.MatchClause == null)
return null;
var unionFind = new UnionFind();
var edgeColumnToAliasesDict = new Dictionary<string, List<string>>(StringComparer.OrdinalIgnoreCase);
var pathDictionary = new Dictionary<string, MatchPath>(StringComparer.OrdinalIgnoreCase);
var matchClause = query.MatchClause;
var nodes = new Dictionary<string, MatchNode>(StringComparer.OrdinalIgnoreCase);
var connectedSubGraphs = new List<ConnectedComponent>();
var subGrpahMap = new Dictionary<string, ConnectedComponent>(StringComparer.OrdinalIgnoreCase);
var parent = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
unionFind.Parent = parent;
// Constructs the graph pattern specified by the path expressions in the MATCH clause
foreach (var path in matchClause.Paths)
{
var index = 0;
MatchEdge preEdge = null;
for (var count = path.PathEdgeList.Count; index < count; ++index)
{
var currentNodeTableRef = path.PathEdgeList[index].Item1;
var currentEdgeColumnRef = path.PathEdgeList[index].Item2;
var currentNodeExposedName = currentNodeTableRef.BaseIdentifier.Value;
var nextNodeTableRef = index != count - 1
? path.PathEdgeList[index + 1].Item1
: path.Tail;
var nextNodeExposedName = nextNodeTableRef.BaseIdentifier.Value;
var patternNode = nodes.GetOrCreate(currentNodeExposedName);
if (patternNode.NodeAlias == null)
{
patternNode.NodeAlias = currentNodeExposedName;
patternNode.Neighbors = new List<MatchEdge>();
patternNode.External = false;
var nodeTable = _context[currentNodeExposedName] as WNamedTableReference;
if (nodeTable != null)
{
patternNode.NodeTableObjectName = nodeTable.TableObjectName;
if (patternNode.NodeTableObjectName.SchemaIdentifier == null)
patternNode.NodeTableObjectName.Identifiers.Insert(0, new Identifier {Value = "dbo"});
}
}
string edgeAlias = currentEdgeColumnRef.Alias;
if (edgeAlias == null)
{
var currentEdgeName = currentEdgeColumnRef.MultiPartIdentifier.Identifiers.Last().Value;
edgeAlias = string.Format("{0}_{1}_{2}", currentNodeExposedName, currentEdgeName,
nextNodeExposedName);
if (edgeColumnToAliasesDict.ContainsKey(currentEdgeName))
{
edgeColumnToAliasesDict[currentEdgeName].Add(edgeAlias);
}
else
{
edgeColumnToAliasesDict.Add(currentEdgeName, new List<string> { edgeAlias });
}
}
Identifier edgeIdentifier = currentEdgeColumnRef.MultiPartIdentifier.Identifiers.Last();
string schema = patternNode.NodeTableObjectName.SchemaIdentifier.Value.ToLower();
string nodeTableName = patternNode.NodeTableObjectName.BaseIdentifier.Value;
string bindTableName =
_context.EdgeNodeBinding[
new Tuple<string, string>(nodeTableName.ToLower(), edgeIdentifier.Value.ToLower())].ToLower();
MatchEdge edge;
if (currentEdgeColumnRef.MinLength == 1 && currentEdgeColumnRef.MaxLength == 1)
{
edge = new MatchEdge
{
SourceNode = patternNode,
EdgeColumn = currentEdgeColumnRef,
EdgeAlias = edgeAlias,
BindNodeTableObjName =
new WSchemaObjectName(
new Identifier {Value = schema},
new Identifier {Value = bindTableName}
),
};
_context.AddEdgeReference(edge);
}
else
{
MatchPath matchPath = new MatchPath
{
SourceNode = patternNode,
EdgeColumn = currentEdgeColumnRef,
EdgeAlias = edgeAlias,
BindNodeTableObjName =
new WSchemaObjectName(
new Identifier {Value = schema},
new Identifier {Value = bindTableName}
),
MinLength = currentEdgeColumnRef.MinLength,
MaxLength = currentEdgeColumnRef.MaxLength,
ReferencePathInfo = false,
AttributeValueDict = currentEdgeColumnRef.AttributeValueDict
};
_context.AddEdgeReference(matchPath);
pathDictionary[edgeAlias] = matchPath;
edge = matchPath;
}
if (preEdge != null)
{
preEdge.SinkNode = patternNode;
}
preEdge = edge;
if (!parent.ContainsKey(currentNodeExposedName))
parent[currentNodeExposedName] = currentNodeExposedName;
if (!parent.ContainsKey(nextNodeExposedName))
parent[nextNodeExposedName] = nextNodeExposedName;
unionFind.Union(currentNodeExposedName, nextNodeExposedName);
patternNode.Neighbors.Add(edge);
}
var tailExposedName = path.Tail.BaseIdentifier.Value;
var tailNode = nodes.GetOrCreate(tailExposedName);
if (tailNode.NodeAlias == null)
{
tailNode.NodeAlias = tailExposedName;
tailNode.Neighbors = new List<MatchEdge>();
var nodeTable = _context[tailExposedName] as WNamedTableReference;
if (nodeTable != null)
{
tailNode.NodeTableObjectName = nodeTable.TableObjectName;
if (tailNode.NodeTableObjectName.SchemaIdentifier == null)
tailNode.NodeTableObjectName.Identifiers.Insert(0, new Identifier {Value = "dbo"});
}
}
if (preEdge != null)
preEdge.SinkNode = tailNode;
}
// Puts nodes into subgraphs
foreach (var node in nodes)
{
string root = unionFind.Find(node.Key);
if (!subGrpahMap.ContainsKey(root))
{
var subGraph = new ConnectedComponent();
subGraph.Nodes[node.Key] = node.Value;
foreach (var edge in node.Value.Neighbors)
{
subGraph.Edges[edge.EdgeAlias] = edge;
}
subGrpahMap[root] = subGraph;
connectedSubGraphs.Add(subGraph);
subGraph.IsTailNode[node.Value] = false;
}
else
{
var subGraph = subGrpahMap[root];
subGraph.Nodes[node.Key] = node.Value;
foreach (var edge in node.Value.Neighbors)
{
subGraph.Edges[edge.EdgeAlias] = edge;
}
subGraph.IsTailNode[node.Value] = false;
}
}
var graph = new MatchGraph
{
ConnectedSubGraphs = connectedSubGraphs,
};
unionFind.Parent = null;
// When an edge in the MATCH clause is not associated with an alias,
// assigns to it a default alias: sourceAlias_EdgeColumnName_sinkAlias.
// Also rewrites edge attributes anywhere in the query that can be bound to this default alias.
var replaceTableRefVisitor = new ReplaceEdgeReferenceVisitor();
replaceTableRefVisitor.Invoke(query, edgeColumnToAliasesDict);
// Rematerializes node tables in the MATCH clause which are defined in the upper-level context
// and join them with the upper-level table references.
RematerilizeExtrenalNodeTableReference(query, nodes);
// Transforms the path reference in the SELECT elements into a
// scalar function to display path information.
TransformPathInfoDisplaySelectElement(query, pathDictionary);
return graph;
}
public override List <Tuple <MatchNode, MatchEdge, List <MatchEdge>, List <MatchEdge>, List <MatchEdge> > > GetOptimizedTraversalOrder(ConnectedComponent subGraph)
{
if (subGraph.Nodes.Count == 1)
{
return
(this.GenerateTraversalOrderFromTraversalChain(
new List <Tuple <MatchNode, MatchEdge, MatchNode, List <MatchEdge>, List <MatchEdge> > >
{
new Tuple <MatchNode, MatchEdge, MatchNode, List <MatchEdge>, List <MatchEdge> >(
subGraph.Nodes.First().Value, null, null, null, null)
}));
}
// If it exists, pick a node without incoming edges as the start point
List <MatchComponent> componentStates = subGraph.Nodes.Where(node => node.Value.ReverseNeighbors.Count == 0).
Select(node => new MatchComponent(node.Value)).Take(1).ToList();
// Otherwise, pick a node randomly as the start point
if (!componentStates.Any())
{
componentStates.Add(new MatchComponent(subGraph.Nodes.First().Value));
}
// DP
while (componentStates.Any())
{
List <MatchComponent> nextCompnentStates = new List <MatchComponent>();
// Iterate on current components
foreach (MatchComponent curComponent in componentStates)
{
OneHeightTree nodeUnits = this.GetNodeUnits(subGraph, curComponent);
if (nodeUnits == null &&
curComponent.ActiveNodeCount == subGraph.ActiveNodeCount &&
curComponent.EdgeMaterilizedDict.Count(e => e.Value == true) == subGraph.Edges.Count(e => e.Value.IsDanglingEdge == false))
{
return(this.GenerateTraversalOrderFromTraversalChain(curComponent.TraversalChain));
}
CandidateJoinUnit candidateUnit = this.GetCandidateUnits2(nodeUnits, curComponent);
// Add it to the current component to generate next states
MatchComponent newComponent = this.GetNextState(curComponent, candidateUnit);
if (nextCompnentStates.Count >= MaxStates)
{
throw new GraphViewException("This graph pattern is not supported yet.");
}
nextCompnentStates.Add(newComponent);
}
componentStates = nextCompnentStates;
}
return(null);
}