47 lines
1.6 KiB
Plaintext
47 lines
1.6 KiB
Plaintext
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[[doc-values]]
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=== `doc_values`
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Most fields are <<mapping-index,indexed>> by default, which makes them
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searchable. The inverted index allows queries to look up the search term in
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unique sorted list of terms, and from that immediately have access to the list
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of documents that contain the term.
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Sorting, aggregations, and access to field values in scripts requires a
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different data access pattern. Instead of lookup up the term and finding
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documents, we need to be able to look up the document and find the terms that
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is has in a field.
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Doc values are the on-disk data structure, built at document index time, which
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makes this data access pattern possible. Doc values are supported on almost
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all field types, with the __notable exception of `analyzed` string fields__.
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All fields which support doc values have them enabled by default. If you are
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sure that you don't need to sort or aggregate on a field, or access the field
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value from a script, you can disable doc values in order to save disk space:
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[source,js]
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--------------------------------------------------
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PUT my_index
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{
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"mappings": {
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"my_type": {
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"properties": {
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"status_code": { <1>
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"type": "string",
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"index": "not_analyzed"
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},
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"session_id": { <2>
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"type": "string",
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"index": "not_analyzed",
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"doc_values": false
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}
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}
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}
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}
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}
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--------------------------------------------------
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// AUTOSENSE
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<1> The `status_code` field has `doc_values` enabled by default.
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<2> The `session_id` has `doc_values` disabled, but can still be queried.
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