[[indices-aliases]] === Update index alias API ++++ Update index alias ++++ Adds or removes index aliases. include::{es-repo-dir}/glossary.asciidoc[tag=index-alias-desc] [source,console] ---- POST /_aliases { "actions" : [ { "add" : { "index" : "my-index-000001", "alias" : "alias1" } } ] } ---- // TEST[setup:my_index] [[indices-aliases-api-request]] ==== {api-request-title} `POST /_aliases` [[indices-aliases-api-desc]] ==== {api-description-title} APIs in Elasticsearch accept an index name when working against a specific index, and several indices when applicable. The index aliases API allows aliasing an index with a name, with all APIs automatically converting the alias name to the actual index name. An alias can also be mapped to more than one index, and when specifying it, the alias will automatically expand to the aliased indices. An alias can also be associated with a filter that will automatically be applied when searching, and routing values. An alias cannot have the same name as an index. [[indices-aliases-api-query-params]] ==== {api-query-parms-title} include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=timeoutparms] [[indices-aliases-api-request-body]] ==== {api-request-body-title} `actions`:: + -- (Required, array of actions) Set of actions to perform. Valid actions include: `add`:: Adds an alias to an index. `remove`:: Removes an alias from an index. `remove_index`:: Deletes an index or index alias, like the <>. You can perform these actions on alias objects. Valid parameters for alias objects include: `index`:: (String) Wildcard expression of index names used to perform the action. + If the `indices` parameter is not specified, this parameter is required. + NOTE: You cannot add <> to an index alias. `indices`:: (Array) Array of index names used to perform the action. + If the `index` parameter is not specified, this parameter is required. + NOTE: You cannot add <> to an index alias. `alias`:: (String) Comma-separated list or wildcard expression of index alias names to add, remove, or delete. + If the `aliases` parameter is not specified, this parameter is required for the `add` or `remove` action. `aliases`:: (Array of strings) Array of index alias names to add, remove, or delete. + If the `alias` parameter is not specified, this parameter is required for the `add` or `remove` action. `filter`:: (Optional, query object) include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=index-alias-filter] + See <> for an example. `is_hidden`:: (Optional, boolean) If `true`, the alias will be excluded from wildcard expressions by default, unless overriden in the request using the `expand_wildcards` parameter, similar to <>. This property must be set to the same value on all indices that share an alias. Defaults to `false`. `must_exist`:: (Optional, boolean) If `true`, the alias to remove must exist. Defaults to `false`. `is_write_index`:: (Optional, boolean) If `true`, assigns the index as an alias's write index. Defaults to `false`. + An alias can have one write index at a time. + See <> for an example. + [IMPORTANT] ==== Aliases that do not explicitly set `is_write_index: true` for an index, and only reference one index, will have that referenced index behave as if it is the write index until an additional index is referenced. At that point, there will be no write index and writes will be rejected. ==== include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=index-routing] + See <> for an example. `index_routing`:: (Optional, string) Custom <> used for the alias's indexing operations. + See <> for an example. `search_routing`:: (Optional, string) Custom <> used for the alias's search operations. + See <> for an example. -- [[indices-aliases-api-example]] ==== {api-examples-title} [[indices-aliases-api-add-alias-ex]] ===== Add an alias The following request adds the `alias1` alias to the `test1` index. [source,console] -------------------------------------------------- POST /_aliases { "actions" : [ { "add" : { "index" : "test1", "alias" : "alias1" } } ] } -------------------------------------------------- // TEST[s/^/PUT test1\nPUT test2\n/] [[indices-aliases-api-remove-alias-ex]] ===== Remove an alias The following request removes the `alias1` alias. [source,console] -------------------------------------------------- POST /_aliases { "actions" : [ { "remove" : { "index" : "test1", "alias" : "alias1" } } ] } -------------------------------------------------- // TEST[continued] [[indices-aliases-api-rename-alias-ex]] ===== Rename an alias Renaming an alias is a simple `remove` then `add` operation within the same API. This operation is atomic, no need to worry about a short period of time where the alias does not point to an index: [source,console] -------------------------------------------------- POST /_aliases { "actions" : [ { "remove" : { "index" : "test1", "alias" : "alias1" } }, { "add" : { "index" : "test1", "alias" : "alias2" } } ] } -------------------------------------------------- // TEST[continued] [[indices-aliases-api-add-multi-alias-ex]] ===== Add an alias to multiple indices Associating an alias with more than one index is simply several `add` actions: [source,console] -------------------------------------------------- POST /_aliases { "actions" : [ { "add" : { "index" : "test1", "alias" : "alias1" } }, { "add" : { "index" : "test2", "alias" : "alias1" } } ] } -------------------------------------------------- // TEST[s/^/PUT test1\nPUT test2\n/] Multiple indices can be specified for an action with the `indices` array syntax: [source,console] -------------------------------------------------- POST /_aliases { "actions" : [ { "add" : { "indices" : ["test1", "test2"], "alias" : "alias1" } } ] } -------------------------------------------------- // TEST[s/^/PUT test1\nPUT test2\n/] To specify multiple aliases in one action, the corresponding `aliases` array syntax exists as well. For the example above, a glob pattern can also be used to associate an alias to more than one index that share a common name: [source,console] -------------------------------------------------- POST /_aliases { "actions" : [ { "add" : { "index" : "test*", "alias" : "all_test_indices" } } ] } -------------------------------------------------- // TEST[s/^/PUT test1\nPUT test2\n/] In this case, the alias is a point-in-time alias that will group all current indices that match, it will not automatically update as new indices that match this pattern are added/removed. It is an error to index to an alias which points to more than one index. It is also possible to swap an index with an alias in one, atomic operation. This means there will be no point in time where the alias points to no index in the cluster state. However, as indexing and searches involve multiple steps, it is possible for the in-flight or queued requests to fail due to a temporarily non-existent index. [source,console] -------------------------------------------------- PUT test <1> PUT test_2 <2> POST /_aliases { "actions" : [ { "add": { "index": "test_2", "alias": "test" } }, { "remove_index": { "index": "test" } } <3> ] } -------------------------------------------------- <1> An index we've added by mistake <2> The index we should have added <3> `remove_index` is just like <> [[filtered]] ===== Filtered aliases Aliases with filters provide an easy way to create different "views" of the same index. The filter can be defined using Query DSL and is applied to all Search, Count, Delete By Query and More Like This operations with this alias. To create a filtered alias, first we need to ensure that the fields already exist in the mapping: [source,console] -------------------------------------------------- PUT /test1 { "mappings": { "properties": { "user" : { "type": "keyword" } } } } -------------------------------------------------- Now we can create an alias that uses a filter on field `user`: [source,console] -------------------------------------------------- POST /_aliases { "actions": [ { "add": { "index": "test1", "alias": "alias2", "filter": { "term": { "user.id": "kimchy" } } } } ] } -------------------------------------------------- // TEST[continued] [[aliases-routing]] ===== Routing It is possible to associate routing values with aliases. This feature can be used together with filtering aliases in order to avoid unnecessary shard operations. The following command creates a new alias `alias1` that points to index `test`. After `alias1` is created, all operations with this alias are automatically modified to use value `1` for routing: [source,console] -------------------------------------------------- POST /_aliases { "actions": [ { "add": { "index": "test", "alias": "alias1", "routing": "1" } } ] } -------------------------------------------------- // TEST[s/^/PUT test\n/] It's also possible to specify different routing values for searching and indexing operations: [source,console] -------------------------------------------------- POST /_aliases { "actions": [ { "add": { "index": "test", "alias": "alias2", "search_routing": "1,2", "index_routing": "2" } } ] } -------------------------------------------------- // TEST[s/^/PUT test\n/] As shown in the example above, search routing may contain several values separated by comma. Index routing can contain only a single value. If a search operation that uses routing alias also has a routing parameter, an intersection of both search alias routing and routing specified in the parameter is used. For example the following command will use "2" as a routing value: [source,console] -------------------------------------------------- GET /alias2/_search?q=user.id:kimchy&routing=2,3 -------------------------------------------------- // TEST[continued] [[aliases-write-index]] ===== Write index It is possible to associate the index pointed to by an alias as the write index. When specified, all index and update requests against an alias that point to multiple indices will attempt to resolve to the one index that is the write index. Only one index per alias can be assigned to be the write index at a time. If no write index is specified and there are multiple indices referenced by an alias, then writes will not be allowed. It is possible to specify an index associated with an alias as a write index using both the aliases API and index creation API. Setting an index to be the write index with an alias also affects how the alias is manipulated during Rollover (see <>). [source,console] -------------------------------------------------- POST /_aliases { "actions": [ { "add": { "index": "test", "alias": "alias1", "is_write_index": true } }, { "add": { "index": "test2", "alias": "alias1" } } ] } -------------------------------------------------- // TEST[s/^/PUT test\nPUT test2\n/] In this example, we associate the alias `alias1` to both `test` and `test2`, where `test` will be the index chosen for writing to. [source,console] -------------------------------------------------- PUT /alias1/_doc/1 { "foo": "bar" } -------------------------------------------------- // TEST[continued] The new document that was indexed to `/alias1/_doc/1` will be indexed as if it were `/test/_doc/1`. [source,console] -------------------------------------------------- GET /test/_doc/1 -------------------------------------------------- // TEST[continued] To swap which index is the write index for an alias, the Aliases API can be leveraged to do an atomic swap. The swap is not dependent on the ordering of the actions. [source,console] -------------------------------------------------- POST /_aliases { "actions": [ { "add": { "index": "test", "alias": "alias1", "is_write_index": false } }, { "add": { "index": "test2", "alias": "alias1", "is_write_index": true } } ] } -------------------------------------------------- // TEST[s/^/PUT test\nPUT test2\n/]