32 lines
1.4 KiB
Plaintext
32 lines
1.4 KiB
Plaintext
[discrete]
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[[search-fields]]
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=== Return fields in a search
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By default, each hit in the search response includes the document
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<<mapping-source-field,`_source`>>, which is the entire JSON object that was
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provided when indexing the document. If you only need certain fields in the
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search response, you can use
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<<request-body-search-source-filtering,source filtering>> to restrict what
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parts of the source are returned.
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Returning fields using only the document source has some limitations:
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* The `_source` field does not include <<multi-fields, multi-fields>> or
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<<alias, field aliases>>. Likewise, a field in the source does not contain
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values copied using the <<copy-to,`copy_to`>> mapping parameter.
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* Since the `_source` is stored as a single field in Lucene, the whole source
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object must be loaded and parsed, even if only a small number of fields are
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needed.
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{es} supports some alternative methods for returning fields that help avoid
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these downsides:
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* The <<request-body-search-docvalue-fields, `docvalue_fields`>>
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parameter allows for loading fields from their doc values. This can be a good
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choice when returning a fairly small number of fields that support doc values,
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such as keywords and dates.
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* It's also possible to store an individual field's values by using the
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<<mapping-store,`store`>> mapping option. You can use the
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<<request-body-search-stored-fields, `stored_fields`>> parameter to return
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these stored values in the search response.
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