Class LeviathanQueryOptions

A class encapsulating run-time options that can be configured for a LeviathanQueryProcessor.

Inheritance
System.Object
LeviathanQueryOptions
LeviathanUpdateOptions
Inherited Members
object.Equals(object)
object.Equals(object, object)
object.GetHashCode()
object.GetType()
object.MemberwiseClone()
object.ReferenceEquals(object, object)
object.ToString()
Namespace: VDS.RDF.Query
Assembly: dotNetRdf.dll
Syntax
public class LeviathanQueryOptions

Properties

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AlgebraOptimisation

Gets/Sets whether Algebra Optimization should be used.

Declaration
public bool AlgebraOptimisation { get; set; }
Property Value
Type Description
System.Boolean
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AlgebraOptimisers

Gets/Sets the optimisers to apply if AlgebraOptimisation is enabled.

Declaration
public IEnumerable<IAlgebraOptimiser> AlgebraOptimisers { get; set; }
Property Value
Type Description
System.Collections.Generic.IEnumerable<T><IAlgebraOptimiser>
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Describer

Gets/Sets the ISparqlDescribe which provides the Describe algorithm you wish to use.

Declaration
public ISparqlDescribe Describer { get; set; }
Property Value
Type Description
ISparqlDescribe
Remarks

By default this will be the ConciseBoundedDescription (CBD) algorithm.

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NodeComparer

Get or set the node comparer to use in evaluation.

Declaration
public ISparqlNodeComparer NodeComparer { get; set; }
Property Value
Type Description
ISparqlNodeComparer
Remarks

You may want to provide a SparqlNodeComparer instance to specify a different culture or compare options for string comparison.

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QueryExecutionTimeout

Gets/Sets the Hard Timeout limit for SPARQL Query Execution (in milliseconds).

Declaration
public long QueryExecutionTimeout { get; set; }
Property Value
Type Description
long
Remarks

This is used to stop SPARQL queries running away and never completing execution, it defaults to 3 mins (180,000 milliseconds).

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RigorousEvaluation

Gets/Sets whether to use rigorous query evaluation.

Declaration
public bool RigorousEvaluation { get; set; }
Property Value
Type Description
System.Boolean
Remarks

Rigorous Query evaluation applies more checks to the triples produced by datasets to ensure they actually match the patterns being scanned. If the underlying index structures are able to guarantee this then rigorous evaluation may be turned off for faster evaluation which it is by default since our default TreeIndexedTripleCollection and TripleCollection implementations will guarantee this.

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StrictOperators

Gets/Sets whether to use strict operators.

Declaration
public bool StrictOperators { get; set; }
Property Value
Type Description
System.Boolean
Remarks

Strict Operators refers to the interpretation of certain operators like + and - in SPARQL expression evaluation. If enabled then the operators will function only as specified in the SPARQL specification. If disabled (which is the default) then certain extensions (which the SPARQL specification allows an implementation to provide) will be allowed e.g. date time arithmetic.

The only time you may want to disable this is if you are developing queries locally which you want to ensure are portable to other systems or when running the SPARQL compliance tests.

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UriFactory

Gets/Sets the URI factory to use during query evaluation.

Declaration
public IUriFactory UriFactory { get; set; }
Property Value
Type Description
IUriFactory
Remarks

When querying an in-memory dataset, using the same URI factory as the graphs being queried, or a child of the URI factor of the graphs being queried will save memory.

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UsePLinqEvaluation

Gets/Sets whether the query engine will try to use PLinq where applicable to evaluate suitable SPARQL constructs in parallel.

Declaration
public bool UsePLinqEvaluation { get; set; }
Property Value
Type Description
System.Boolean
Remarks

Defaults to true.

Extension Methods