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703dbff83d
The `exists` and `missing` filters need to merge postings lists of all existing terms, which can be very costly, especially on high-cardinality fields. This commit indexes the field names of a document under `_field_names` and reuses it to speed up the `exists` and `missing` filters. This is only enabled for indices that are created on or after Elasticsearch 1.3.0. Close #5659
12 lines
367 B
Plaintext
12 lines
367 B
Plaintext
[[mapping-field-names-field]]
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=== `_field_names`
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coming[1.3.0]
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The `_field_names` field indexes the field names of a document, which can later
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be used to search for documents based on the fields that they contain typically
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using the `exists` and `missing` filters.
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`_field_names` is indexed by default for indices that have been created after
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Elasticsearch 1.3.0.
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