Class CachedFilterBuilder

Filters are cached in an LRU Cache keyed on the contained query or filter object. Using this will speed up overall performance for repeated uses of the same expensive query/filter. The sorts of queries/filters likely to benefit from caching need not necessarily be complex - e.g. simple TermQuerys with a large DF (document frequency) can be expensive on large indexes. A good example of this might be a term query on a field with only 2 possible values - "true" or "false". In a large index, querying or filtering on this field requires reading millions of document ids from disk which can more usefully be cached as a filter bitset.

For Queries/Filters to be cached and reused the object must implement hashcode and equals methods correctly so that duplicate queries/filters can be detected in the cache.

The CoreParser.maxNumCachedFilters property can be used to control the size of the LRU Cache established during the construction of CoreParser instances.

Inheritance

object

CachedFilterBuilder

Implements

IFilterBuilder

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Lucene.Net.QueryParsers.Xml.Builders

Assembly: Lucene.Net.QueryParser.dll

Syntax

public class CachedFilterBuilder : IFilterBuilder

Constructors

CachedFilterBuilder(QueryBuilderFactory, FilterBuilderFactory, int)

Filters are cached in an LRU Cache keyed on the contained query or filter object. Using this will speed up overall performance for repeated uses of the same expensive query/filter. The sorts of queries/filters likely to benefit from caching need not necessarily be complex - e.g. simple TermQuerys with a large DF (document frequency) can be expensive on large indexes. A good example of this might be a term query on a field with only 2 possible values - "true" or "false". In a large index, querying or filtering on this field requires reading millions of document ids from disk which can more usefully be cached as a filter bitset.

For Queries/Filters to be cached and reused the object must implement hashcode and equals methods correctly so that duplicate queries/filters can be detected in the cache.

The CoreParser.maxNumCachedFilters property can be used to control the size of the LRU Cache established during the construction of CoreParser instances.

Declaration

public CachedFilterBuilder(QueryBuilderFactory queryFactory, FilterBuilderFactory filterFactory, int cacheSize)

Parameters

Type	Name	Description
QueryBuilderFactory	queryFactory
FilterBuilderFactory	filterFactory
int	cacheSize

Methods

GetFilter(XmlElement)

Filters are cached in an LRU Cache keyed on the contained query or filter object. Using this will speed up overall performance for repeated uses of the same expensive query/filter. The sorts of queries/filters likely to benefit from caching need not necessarily be complex - e.g. simple TermQuerys with a large DF (document frequency) can be expensive on large indexes. A good example of this might be a term query on a field with only 2 possible values - "true" or "false". In a large index, querying or filtering on this field requires reading millions of document ids from disk which can more usefully be cached as a filter bitset.

For Queries/Filters to be cached and reused the object must implement hashcode and equals methods correctly so that duplicate queries/filters can be detected in the cache.

The CoreParser.maxNumCachedFilters property can be used to control the size of the LRU Cache established during the construction of CoreParser instances.

Declaration

public virtual Filter GetFilter(XmlElement e)

Parameters

Type	Name	Description
XmlElement	e

Returns

Type	Description
Filter

Implements

IFilterBuilder