private static WColumnReferenceExpression GetNodeColumnReferenceExprFromLink(CompileLink link)
{
if (link is MatchEdge)
{
MatchEdge edge = link as MatchEdge;
if (edge.EdgeType == WEdgeType.OutEdge)
{
return(SqlUtil.GetColumnReferenceExpr(edge.LinkAlias,
edge.IsReversed ? GremlinKeyword.EdgeSinkV : GremlinKeyword.EdgeSourceV));
}
else if (edge.EdgeType == WEdgeType.InEdge)
{
return(SqlUtil.GetColumnReferenceExpr(edge.LinkAlias,
edge.IsReversed ? GremlinKeyword.EdgeSourceV : GremlinKeyword.EdgeSinkV));
}
else
{
return(SqlUtil.GetColumnReferenceExpr(edge.LinkAlias, GremlinKeyword.EdgeOtherV));
}
}
else if (link is PredicateLink)
{
PredicateLink predicateLink = link as PredicateLink;
if (predicateLink.BooleanExpression is WEdgeVertexBridgeExpression)
{
return((predicateLink.BooleanExpression as WEdgeVertexBridgeExpression).FirstExpr as WColumnReferenceExpression);
}
}
throw new QueryCompilationException("Cannot support " + link + " as a traversal link or an edge");
}
/// <summary>
/// Given a node / TVF, a traversalLink and backwardEdges, try to find all predicates that can be evaluated
/// </summary>
/// <param name="node"></param>
/// <param name="traversalLink"></param>
/// <param name="backwardEdges"></param>
/// <param name="predicateLinksAccessedTableAliases"></param>
private List <Tuple <PredicateLink, int> > FindPredicates(
CompileNode node,
CompileLink traversalLink,
List <Tuple <MatchEdge, int> > backwardEdges,
List <Tuple <PredicateLink, HashSet <string> > > predicateLinksAccessedTableAliases)
{
// Record temporary aliases and predicates
HashSet <string> temporaryAliases = new HashSet <string>(this.ExistingNodesAndEdges);
HashSet <string> temporaryPredicates = new HashSet <string>(this.ExistingPredicateLinks);
List <Tuple <PredicateLink, int> > forwardLinks = new List <Tuple <PredicateLink, int> >();
// priority = 1
// retrieve traversalLink and add predicates
if (traversalLink != null && !this.ExistingNodesAndEdges.Contains(traversalLink.LinkAlias))
{
// Find predicates that can be evaluated after retrieving this traversalLink
if (traversalLink is MatchEdge)
{
temporaryAliases.Add(traversalLink.LinkAlias);
}
else if (traversalLink is PredicateLink)
{
temporaryPredicates.Add(traversalLink.LinkAlias);
}
else
{
throw new QueryCompilationException("Cannot support " + traversalLink + " as a traversal link or an edge");
}
foreach (Tuple <PredicateLink, HashSet <string> > tuple in predicateLinksAccessedTableAliases)
{
if (!temporaryPredicates.Contains(tuple.Item1.LinkAlias) &&
temporaryAliases.IsSupersetOf(tuple.Item2))
{
temporaryPredicates.Add(tuple.Item1.LinkAlias);
forwardLinks.Add(new Tuple <PredicateLink, int>(tuple.Item1, 1));
}
}
// Make sure the all existing edges and this traversalLink are consistent
// Because all existing edges are consistent, we just need make one exstring edge and this traversalLink consistent
MatchNode matchNode = node as MatchNode;
WColumnReferenceExpression nodeColumnReferenceExprFromTraversalLink = GetNodeColumnReferenceExprFromLink(traversalLink);
WColumnReferenceExpression nodeColumnReferenceExprFromAnExistingEdge = GetNodeColumnReferenceExprFromAnExistingEdge(matchNode, this.ExistingNodesAndEdges);
if (nodeColumnReferenceExprFromTraversalLink != null &&
nodeColumnReferenceExprFromAnExistingEdge != null)
{
forwardLinks.Add(
new Tuple <PredicateLink, int>(
new PredicateLink(
SqlUtil.GetEqualBooleanComparisonExpr(nodeColumnReferenceExprFromTraversalLink,
nodeColumnReferenceExprFromAnExistingEdge)), 1));
}
}
// priority = 2
// retrieve node and some edges and add predicates
temporaryAliases.Add(node.NodeAlias);
foreach (Tuple <MatchEdge, int> tuple in backwardEdges)
{
if (tuple.Item2 == 2)
{
temporaryAliases.Add(tuple.Item1.LinkAlias);
MatchNode otherNode = tuple.Item1.SinkNode;
WColumnReferenceExpression nodeColumnReferenceExprFromBackwardEdge = null;
WColumnReferenceExpression nodeColumnReferenceExprFromAnExistingEdge = GetNodeColumnReferenceExprFromAnExistingEdge(otherNode, this.ExistingNodesAndEdges);
if (nodeColumnReferenceExprFromAnExistingEdge != null)
{
foreach (MatchEdge edge in otherNode.Neighbors)
{
if (edge.LinkAlias == tuple.Item1.LinkAlias)
{
nodeColumnReferenceExprFromBackwardEdge = GetNodeColumnReferenceExprFromLink(edge);
break;
}
}
if (nodeColumnReferenceExprFromBackwardEdge == null)
{
foreach (MatchEdge edge in otherNode.ReverseNeighbors)
{
if (edge.LinkAlias == tuple.Item1.LinkAlias)
{
nodeColumnReferenceExprFromBackwardEdge = GetNodeColumnReferenceExprFromLink(edge);
break;
}
}
}
if (nodeColumnReferenceExprFromBackwardEdge == null)
{
foreach (MatchEdge edge in otherNode.DanglingEdges)
{
if (edge.LinkAlias == tuple.Item1.LinkAlias)
{
nodeColumnReferenceExprFromBackwardEdge = GetNodeColumnReferenceExprFromLink(edge);
break;
}
}
}
}
// Because all existing edges are consistent, we just need make one exstring edge and this edge consistent
if (nodeColumnReferenceExprFromBackwardEdge != null &&
nodeColumnReferenceExprFromAnExistingEdge != null)
{
temporaryPredicates.Add(tuple.Item1.LinkAlias);
forwardLinks.Add(
new Tuple <PredicateLink, int>(
new PredicateLink(
SqlUtil.GetEqualBooleanComparisonExpr(nodeColumnReferenceExprFromBackwardEdge,
nodeColumnReferenceExprFromAnExistingEdge)), 2));
}
}
}
// Check predicates
foreach (Tuple <PredicateLink, HashSet <string> > tuple in predicateLinksAccessedTableAliases)
{
if (!temporaryPredicates.Contains(tuple.Item1.LinkAlias) &&
temporaryAliases.IsSupersetOf(tuple.Item2))
{
temporaryPredicates.Add(tuple.Item1.LinkAlias);
forwardLinks.Add(new Tuple <PredicateLink, int>(tuple.Item1, 2));
}
}
// priority = 3
// retrieve another edges and add predicates
foreach (Tuple <MatchEdge, int> tuple in backwardEdges)
{
if (tuple.Item2 == 3)
{
temporaryAliases.Add(tuple.Item1.LinkAlias);
MatchNode otherNode = tuple.Item1.SinkNode;
WColumnReferenceExpression nodeColumnReferenceExprFromBackwardEdge = null;
WColumnReferenceExpression nodeColumnReferenceExprFromAnExistingEdge = GetNodeColumnReferenceExprFromAnExistingEdge(otherNode, this.ExistingNodesAndEdges);
if (nodeColumnReferenceExprFromAnExistingEdge != null)
{
foreach (MatchEdge edge in otherNode.Neighbors)
{
if (edge.LinkAlias == tuple.Item1.LinkAlias)
{
nodeColumnReferenceExprFromBackwardEdge = GetNodeColumnReferenceExprFromLink(edge);
break;
}
}
if (nodeColumnReferenceExprFromBackwardEdge == null)
{
foreach (MatchEdge edge in otherNode.ReverseNeighbors)
{
if (edge.LinkAlias == tuple.Item1.LinkAlias)
{
nodeColumnReferenceExprFromBackwardEdge = GetNodeColumnReferenceExprFromLink(edge);
break;
}
}
}
if (nodeColumnReferenceExprFromBackwardEdge == null)
{
foreach (MatchEdge edge in otherNode.DanglingEdges)
{
if (edge.LinkAlias == tuple.Item1.LinkAlias)
{
nodeColumnReferenceExprFromBackwardEdge = GetNodeColumnReferenceExprFromLink(edge);
break;
}
}
}
}
// Because all existing edges are consistent, we just need make one exstring edge and this edge consistent
if (nodeColumnReferenceExprFromBackwardEdge != null &&
nodeColumnReferenceExprFromAnExistingEdge != null)
{
temporaryPredicates.Add(tuple.Item1.LinkAlias);
forwardLinks.Add(
new Tuple <PredicateLink, int>(
new PredicateLink(
SqlUtil.GetEqualBooleanComparisonExpr(nodeColumnReferenceExprFromBackwardEdge,
nodeColumnReferenceExprFromAnExistingEdge)), 3));
}
}
}
// Check predicates
foreach (Tuple <PredicateLink, HashSet <string> > tuple in predicateLinksAccessedTableAliases)
{
if (!temporaryPredicates.Contains(tuple.Item1.LinkAlias) &&
temporaryAliases.IsSupersetOf(tuple.Item2))
{
temporaryPredicates.Add(tuple.Item1.LinkAlias);
forwardLinks.Add(new Tuple <PredicateLink, int>(tuple.Item1, 3));
}
}
return(forwardLinks);
}
