29 lines
987 B
Plaintext
29 lines
987 B
Plaintext
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[[java-joining-queries]]
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=== Joining queries
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Performing full SQL-style joins in a distributed system like Elasticsearch is
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prohibitively expensive. Instead, Elasticsearch offers two forms of join
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which are designed to scale horizontally.
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<<java-query-dsl-nested-query,`nested` query>>::
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Documents may contains fields of type `nested`. These
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fields are used to index arrays of objects, where each object can be queried
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(with the `nested` query) as an independent document.
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<<java-query-dsl-has-child-query,`has_child`>> and <<java-query-dsl-has-parent-query,`has_parent`>> queries::
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A parent-child relationship can exist between two
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document types within a single index. The `has_child` query returns parent
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documents whose child documents match the specified query, while the
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`has_parent` query returns child documents whose parent document matches the
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specified query.
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include::nested-query.asciidoc[]
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include::has-child-query.asciidoc[]
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include::has-parent-query.asciidoc[]
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