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TripleIndexType Enumeration

Possible Triple Index types.

Namespace:  VDS.RDF
Assembly:  dotNetRDF (in dotNetRDF.dll) Version:
public enum TripleIndexType
  Member nameValueDescription
NoVariables-2 No Index should be used as the Pattern does not use Variables
None-1 No Index should be used as the Pattern is three Variables
Subject2 Subject Index should be used
Predicate1 Predicate Index should be used
Object0 Object Index should be used
SubjectPredicate5 Subject-Predicate Index should be used
PredicateObject3 Predicate-Object Index should be used
SubjectObject4 Subject-Object Index should be used

Index types are given Integer values with the lowest being the least useful index and the highest being most useful index. Non-Index based Patterns are given arbitrary high values since these will typically never be used as these items are usually inserted into a Graph Pattern after the ordering step.

When used to sort Patterns as part of query optimisation the patterns are partially ordered on the usefullness of their index since more useful indexes are considered more likely to return fewer results which will help restrict the query space earlier in the execution process.

See Also