Package com.lucidworks.search.dsl.request.query

Class 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".

    • Constructor Detail

      • JoinQuery

        public JoinQuery​(java.lang.String from,
                 java.lang.String to,
                 java.lang.String fromIndex,
                 Query query)

    • Method Detail

      • getTo

        public java.lang.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 java.lang.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 java.lang.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 java.util.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.