[[doc-values]] === `doc_values` Most fields are <> by default, which makes them searchable. The inverted index allows queries to look up the search term in unique sorted list of terms, and from that immediately have access to the list of documents that contain the term. Sorting, aggregations, and access to field values in scripts requires a different data access pattern. Instead of looking up the term and finding documents, we need to be able to look up the document and find the terms that it has in a field. Doc values are the on-disk data structure, built at document index time, which makes this data access pattern possible. They store the same values as the `_source` but in a column-oriented fashion that is way more efficient for sorting and aggregations. Doc values are supported on almost all field types, with the __notable exception of `analyzed` string fields__. All fields which support doc values have them enabled by default. If you are sure that you don't need to sort or aggregate on a field, or access the field value from a script, you can disable doc values in order to save disk space: [source,js] -------------------------------------------------- PUT my_index { "mappings": { "my_type": { "properties": { "status_code": { <1> "type": "keyword" }, "session_id": { <2> "type": "keyword", "doc_values": false } } } } } -------------------------------------------------- // CONSOLE <1> The `status_code` field has `doc_values` enabled by default. <2> The `session_id` has `doc_values` disabled, but can still be queried. TIP: The `doc_values` setting is allowed to have different settings for fields of the same name in the same index. It can be disabled (set to `false`) on existing fields using the <>.