Package org.apache.solr.search

Class CollapsingQParserPlugin

java.lang.Object

org.apache.solr.search.QParserPlugin

org.apache.solr.search.CollapsingQParserPlugin

All Implemented Interfaces:

SolrInfoBean, NamedListInitializedPlugin

public class CollapsingQParserPlugin
extends QParserPlugin

The CollapsingQParserPlugin is a PostFilter that performs field collapsing. This is a high performance alternative to standard Solr field collapsing (with ngroups) when the number of distinct groups in the result set is high.

Sample syntax:

Collapse based on the highest scoring document:

fq=(!collapse field=field_name}

Collapse based on the min value of a numeric field:

fq={!collapse field=field_name min=field_name}

Collapse based on the max value of a numeric field:

fq={!collapse field=field_name max=field_name}

Collapse with a null policy:

fq={!collapse field=field_name nullPolicy=nullPolicy}

There are three null policies:
ignore : removes docs with a null value in the collapse field (default).
expand : treats each doc with a null value in the collapse field as a separate group.
collapse : collapses all docs with a null value into a single group using either highest score, or min/max.

The CollapsingQParserPlugin fully supports the QueryElevationComponent

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	CollapsingQParserPlugin.CollapseScore
static class	CollapsingQParserPlugin.CollapsingPostFilter
static class	CollapsingQParserPlugin.GroupHeadSelector	Models all the information about how group head documents should be selected
static class	CollapsingQParserPlugin.GroupHeadSelectorType

Nested classes/interfaces inherited from interface org.apache.solr.core.SolrInfoBean

SolrInfoBean.Category, SolrInfoBean.Group

Field Summary

Fields

Modifier and Type	Field	Description
static String	HINT_MULTI_DOCVALUES
static String	HINT_TOP_FC
static String	NAME
static String	NULL_COLLAPSE
static String	NULL_EXPAND
static String	NULL_IGNORE

Fields inherited from class org.apache.solr.search.QParserPlugin

DEFAULT_QTYPE, standardPlugins

Constructor Summary

Constructors

Constructor	Description
CollapsingQParserPlugin()

Method Summary

Modifier and Type	Method	Description
QParser	createParser(String qstr, SolrParams localParams, SolrParams params, SolrQueryRequest request)	return a QParser
static org.apache.lucene.index.LeafReader	getTopFieldCacheReader(SolrIndexSearcher searcher, String collapseField)	This forces the use of the top level field cache for String fields.
static org.apache.lucene.search.Sort	rewriteSort(SortSpec sortSpec, org.apache.lucene.search.IndexSearcher searcher)	Helper method for rewriting the Sort associated with a SortSpec.

Methods inherited from class org.apache.solr.search.QParserPlugin

getCategory, getDescription, getMetricNames, getName, init

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.solr.core.SolrInfoBean

getMetricRegistry, getMetricsSnapshot, registerMetricName

Field Detail

NAME

public static final String NAME

See Also:

Constant Field Values

NULL_COLLAPSE

public static final String NULL_COLLAPSE

See Also:

Constant Field Values

NULL_IGNORE

public static final String NULL_IGNORE

See Also:

Constant Field Values

NULL_EXPAND

public static final String NULL_EXPAND

See Also:

Constant Field Values

HINT_TOP_FC

public static final String HINT_TOP_FC

See Also:

Constant Field Values

HINT_MULTI_DOCVALUES

public static final String HINT_MULTI_DOCVALUES

See Also:

Constant Field Values

Constructor Detail

CollapsingQParserPlugin

public CollapsingQParserPlugin()

Method Detail

createParser

public QParser createParser(String qstr,
                            SolrParams localParams,
                            SolrParams params,
                            SolrQueryRequest request)

Description copied from class: QParserPlugin

return a QParser

Specified by:

createParser in class QParserPlugin

getTopFieldCacheReader

public static org.apache.lucene.index.LeafReader getTopFieldCacheReader(SolrIndexSearcher searcher,
                                                                        String collapseField)

This forces the use of the top level field cache for String fields. This is VERY fast at query time but slower to warm and causes insanity.

rewriteSort

public static org.apache.lucene.search.Sort rewriteSort(SortSpec sortSpec,
                                                        org.apache.lucene.search.IndexSearcher searcher)
                                                 throws IOException

Helper method for rewriting the Sort associated with a SortSpec. Handles the special case default of relevancy sort (ie: a SortSpec w/null Sort object)

Throws:

IOException