com.lucidworks.search.dsl.request.query

Class JoinQuery

java.lang.Object

com.lucidworks.search.dsl.DslBase

com.lucidworks.search.dsl.request.DslCloneable

com.lucidworks.search.dsl.request.query.Query

com.lucidworks.search.dsl.request.query.JoinQuery

public class JoinQuery
extends Query

A query which joins or traces relationships between documents A query ("query") identifies preliminary or seed matches. The "from" field values in all of these matches are brought together into a set. The query then returns all documents whose "to" field contains a value from this set.

The semantics mirror that of a SQL "nested query" of the form:

     SELECT ...
     FROM ...
     WHERE $to IN (SELECT $from FROM ... WHERE $query)
 

In select circumstances, JoinQuery supports running the subquery on a separate collection. In these cases this collection can be specified using "fromIndex".

Field Summary

Fields

Modifier and Type	Field and Description
static String	TYPE

Constructor Summary

Constructors

Constructor and Description
JoinQuery(String from, String to, String fromIndex, Query query)

Method Summary

Modifier and Type	Method and Description
JoinQuery	clone()
List<Query>	getChildQueries() Returns all the children of the query in question.
String	getFrom()
String	getFromIndex()
Query	getQuery()
String	getTo()
boolean	isEmptyQuery()
boolean	removeChildQuery(Query toRemove) Remove 'toRemove', if 'toRemove' is currently a child of this Query object.
boolean	replaceChildQuery(Query toReplace, Query replacement) Swap 'replacement' in as a replacement, if 'toReplace' is currently a child of this Query object.

Methods inherited from class com.lucidworks.search.dsl.request.DslCloneable

clone, deepClone

Methods inherited from class com.lucidworks.search.dsl.DslBase

equals, hashCode, toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

TYPE

public static final String TYPE

See Also:

Constant Field Values

Constructor Detail

JoinQuery

public JoinQuery(String from,
                 String to,
                 String fromIndex,
                 Query query)

Method Detail

getTo

public String getTo()

Returns:

the field name compared against the set of "from" field values. The overall result set contains documents whose "to" field contains any of the values in the "from" field of subquery matches.

getFrom

public String getFrom()

Returns:

the field name containing the values of interest in the subquery matches. All values in this field matched by the subquery are gathered into a set and used to identify the documents matching the overall query

getFromIndex

public String getFromIndex()

Returns:

a separate collection to run the subquery on. This option is only supported conditionally based on backend- specific requirements. If not specified, the subquery is run on the same collection that the "to" values are gathered in.

getQuery

public Query getQuery()

Returns:

the subquery used to identify the documents whose "from" field values are of interest.

getChildQueries

public List<Query> getChildQueries()

Description copied from class: Query

Returns all the children of the query in question. The returned List is provided as a copy - changes made to it do not impact the originating Query object in any way.

Specified by:

getChildQueries in class Query

replaceChildQuery

public boolean replaceChildQuery(Query toReplace,
                                 Query replacement)

Description copied from class: Query

Swap 'replacement' in as a replacement, if 'toReplace' is currently a child of this Query object. Because a tree of Query objects might conceivably have repeated clauses, this method is implemented to test 'toReplace' using reference-equality instead of value-equality.

Specified by:

replaceChildQuery in class Query

Returns:

true if a replacement was made, false otherwise.

removeChildQuery

public boolean removeChildQuery(Query toRemove)

Description copied from class: Query

Remove 'toRemove', if 'toRemove' is currently a child of this Query object. Because a tree of Query objects might conceivably have repeated clauses, this method is implemented to test 'toRemove' using reference-equality instead of value-equality.

Specified by:

removeChildQuery in class Query

Returns:

true if a removal was made, false otherwise.

isEmptyQuery

public boolean isEmptyQuery()

Specified by:

isEmptyQuery in class Query

Returns:

true if this query is now essentially "empty" (doesn't affect query logic at all) and can now be removed from the query tree. This can happen, for example, if all child queries were removed and the query logic depends on having at least one child query.

clone

public JoinQuery clone()

Specified by:

clone in class Query