270 lines
8.2 KiB
Plaintext
270 lines
8.2 KiB
Plaintext
[[api-conventions]]
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= API Conventions
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[partintro]
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--
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The *elasticsearch* REST APIs are exposed using:
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* <<modules-http,JSON over HTTP>>,
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* <<modules-thrift,thrift>>,
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* <<modules-memcached,memcached>>.
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The conventions listed in this chapter can be applied throughout the REST
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API, unless otherwise specified.
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* <<multi-index>>
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* <<common-options>>
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--
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[[multi-index]]
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== Multiple Indices
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Most APIs that refer to an `index` parameter support execution across multiple indices,
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using simple `test1,test2,test3` notation (or `_all` for all indices). It also
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support wildcards, for example: `test*`, and the ability to "add" (`+`)
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and "remove" (`-`), for example: `+test*,-test3`.
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All multi indices API support the following url query string parameters:
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`ignore_unavailable`::
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Controls whether to ignore if any specified indices are unavailable, this
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includes indices that don't exist or closed indices. Either `true` or `false`
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can be specified.
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`allow_no_indices`::
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Controls whether to fail if a wildcard indices expressions results into no
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concrete indices. Either `true` or `false` can be specified. For example if
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the wildcard expression `foo*` is specified and no indices are available that
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start with `foo` then depending on this setting the request will fail. This
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setting is also applicable when `_all`, `*` or no index has been specified.
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`expand_wildcards`::
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Controls to what kind of concrete indices wildcard indices expression expand
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to. If `open` is specified then the wildcard expression if expanded to only
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open indices and if `closed` is specified then the wildcard expression if
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expanded only to closed indices. Also both values (`open,closed`) can be
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specified to expand to all indices.
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The defaults settings for the above parameters depend on the api being used.
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NOTE: Single index APIs such as the <<docs>> and the
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<<indices-aliases,single-index `alias` APIs>> do not support multiple indices.
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[[common-options]]
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== Common options
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The following options can be applied to all of the REST APIs.
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[float]
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=== Pretty Results
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When appending `?pretty=true` to any request made, the JSON returned
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will be pretty formatted (use it for debugging only!). Another option is
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to set `format=yaml` which will cause the result to be returned in the
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(sometimes) more readable yaml format.
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[float]
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=== Human readable output
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Statistics are returned in a format suitable for humans
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(eg `"exists_time": "1h"` or `"size": "1kb"`) and for computers
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(eg `"exists_time_in_millis": 3600000`` or `"size_in_bytes": 1024`).
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The human readable values can be turned off by adding `?human=false`
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to the query string. This makes sense when the stats results are
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being consumed by a monitoring tool, rather than intended for human
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consumption. The default for the `human` flag is
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`false`. added[1.00.Beta,Previously defaulted to `true`]
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[float]
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=== Flat Settings
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The `flat_settings` flag affects rendering of the lists of settings. When
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flat_settings` flag is `true` settings are returned in a flat format:
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[source,js]
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--------------------------------------------------
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{
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"persistent" : { },
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"transient" : {
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"discovery.zen.minimum_master_nodes" : "1"
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}
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}
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--------------------------------------------------
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When the `flat_settings` flag is `false` settings are returned in a more
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human readable structured format:
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[source,js]
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--------------------------------------------------
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{
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"persistent" : { },
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"transient" : {
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"discovery" : {
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"zen" : {
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"minimum_master_nodes" : "1"
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}
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}
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}
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}
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--------------------------------------------------
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By default the `flat_settings` is set to `false`.
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[float]
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=== Parameters
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Rest parameters (when using HTTP, map to HTTP URL parameters) follow the
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convention of using underscore casing.
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[float]
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=== Boolean Values
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All REST APIs parameters (both request parameters and JSON body) support
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providing boolean "false" as the values: `false`, `0`, `no` and `off`.
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All other values are considered "true". Note, this is not related to
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fields within a document indexed treated as boolean fields.
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[float]
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=== Number Values
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All REST APIs support providing numbered parameters as `string` on top
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of supporting the native JSON number types.
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[[time-units]]
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[float]
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=== Time units
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Whenever durations need to be specified, eg for a `timeout` parameter, the duration
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can be specified as a whole number representing time in milliseconds, or as a time value like `2d` for 2 days. The supported units are:
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[horizontal]
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`y`:: Year
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`M`:: Month
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`w`:: Week
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`h`:: Hour
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`m`:: Minute
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`s`:: Second
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[[distance-units]]
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[float]
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=== Distance Units
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Wherever distances need to be specified, such as the `distance` parameter in
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the <<query-dsl-geo-distance-filter>>) or the `precision` parameter in the
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<<query-dsl-geohash-cell-filter>>, the default unit if none is specified is
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the meter. Distances can be specified in other units, such as `"1km"` or
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`"2mi"` (2 miles).
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The full list of units is listed below:
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[horizontal]
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Mile:: `mi` or `miles`
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Yard:: `yd` or `yards`
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Feet:: `ft` or `feet`
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Inch:: `in` or `inch`
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Kilometer:: `km` or `kilometers`
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Meter:: `m` or `meters`
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Centimeter:: `cm` or `centimeters`
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Millimeter:: `mm` or `millimeters`
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[[fuzziness]]
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[float]
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=== Fuzziness
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Some queries and APIs support parameters to allow inexact _fuzzy_ matching,
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using the `fuzziness` parameter. The `fuzziness` parameter is context
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sensitive which means that it depends on the type of the field being queried:
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[float]
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==== Numeric, date and IPv4 fields
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When querying numeric, date and IPv4 fields, `fuzziness` is interpreted as a
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`+/- margin. It behaves like a <<query-dsl-range-query>> where:
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-fuzziness <= field value <= +fuzziness
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The `fuzziness` parameter should be set to a numeric value, eg `2` or `2.0`. A
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`date` field interprets a long as milliseconds, but also accepts a string
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containing a time value -- `"1h"` -- as explained in <<time-units>>. An `ip`
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field accepts a long or another IPv4 address (which will be converted into a
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long).
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[float]
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==== String fields
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When querying `string` fields, `fuzziness` is interpreted as a
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http://en.wikipedia.org/wiki/Levenshtein_distance[Levenshtein Edit Distance]
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-- the number of one character changes that need to be made to one string to
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make it the same as another string.
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The `fuzziness` parameter can be specified as:
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`0`, `1`, `2`::
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the maximum allowed Levenshtein Edit Distance (or number of edits)
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`AUTO`::
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+
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--
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generates an edit distance based on the length of the term. For lengths:
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`0..1`:: must match exactly
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`1..4`:: one edit allowed
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`>4`:: two edits allowed
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`AUTO` should generally be the preferred value for `fuzziness`.
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--
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`0.0..1.0`::
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converted into an edit distance using the formula: `length(term) * (1.0 -
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fuzziness)`, eg a `fuzziness` of `0.6` with a term of length 10 would result
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in an edit distance of `4`. Note: in all APIs except for the
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<<query-dsl-flt-query>>, the maximum allowed edit distance is `2`.
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[float]
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=== Result Casing
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All REST APIs accept the `case` parameter. When set to `camelCase`, all
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field names in the result will be returned in camel casing, otherwise,
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underscore casing will be used. Note, this does not apply to the source
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document indexed.
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[float]
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=== JSONP
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All REST APIs accept a `callback` parameter resulting in a
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http://en.wikipedia.org/wiki/JSONP[JSONP] result.
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[float]
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=== Request body in query string
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For libraries that don't accept a request body for non-POST requests,
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you can pass the request body as the `source` query string parameter
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instead.
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[[url-access-control]]
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== URL-based access control
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Many users use a proxy with URL-based access control to secure access to
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Elasticsearch indices. For <<search-multi-search,multi-search>>,
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<<docs-multi-get,multi-get>> and <<docs-bulk,bulk>> requests, the user has
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the choice of specifying an index in the URL and on each individual request
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within the request body. This can make URL-based access control challenging.
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To prevent the user from overriding the index which has been specified in the
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URL, add this setting to the `config.yml` file:
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rest.action.multi.allow_explicit_index: false
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The default value is `true`, but when set to `false`, Elasticsearch will
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reject requests that have an explicit index specified in the request body.
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