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Index Aliases
editIndex Aliases
editAPIs in elasticsearch accept an index name when working against a specific index, and several indices when applicable. The index aliases API allow to alias 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 aliases indices. An alias can also be associated with a filter that will automatically be applied when searching, and routing values.
Here is a sample of associating the alias alias1
with index test1
:
curl -XPOST 'http://localhost:9200/_aliases' -d ' { "actions" : [ { "add" : { "index" : "test1", "alias" : "alias1" } } ] }'
An alias can also be removed, for example:
curl -XPOST 'http://localhost:9200/_aliases' -d ' { "actions" : [ { "remove" : { "index" : "test1", "alias" : "alias1" } } ] }'
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:
curl -XPOST 'http://localhost:9200/_aliases' -d ' { "actions" : [ { "remove" : { "index" : "test1", "alias" : "alias1" } }, { "add" : { "index" : "test1", "alias" : "alias2" } } ] }'
Associating an alias with more than one index are simply several add
actions:
curl -XPOST 'http://localhost:9200/_aliases' -d ' { "actions" : [ { "add" : { "index" : "test1", "alias" : "alias1" } }, { "add" : { "index" : "test2", "alias" : "alias1" } } ] }'
It is an error to index to an alias which points to more than one index.
Filtered Aliases
editAliases 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:
curl -XPUT 'http://localhost:9200/test1' -d '{ "mappings": { "type1": { "properties": { "user" : { "type": "string", "index": "not_analyzed" } } } } }
Now we can create an alias that uses a filter on field user
:
curl -XPOST 'http://localhost:9200/_aliases' -d '{ "actions" : [ { "add" : { "index" : "test1", "alias" : "alias2", "filter" : { "term" : { "user" : "kimchy" } } } } ] }'
Routing
editIt 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:
curl -XPOST 'http://localhost:9200/_aliases' -d ' { "actions" : [ { "add" : { "index" : "test", "alias" : "alias1", "routing" : "1" } } ] }'
It’s also possible to specify different routing values for searching and indexing operations:
curl -XPOST 'http://localhost:9200/_aliases' -d ' { "actions" : [ { "add" : { "index" : "test", "alias" : "alias2", "search_routing" : "1,2", "index_routing" : "2" } } ] }'
As shown in the example above, search routing may contain several values separated by comma. Index routing can contain only a single value.
If an operation that uses routing alias also has a routing parameter, an intersection of both alias routing and routing specified in the parameter is used. For example the following command will use "2" as a routing value:
curl -XGET 'http://localhost:9200/alias2/_search?q=user:kimchy&routing=2,3'
Add a single alias
editAn alias can also be added with the endpoint
PUT /{index}/_alias/{name}
where
|
The index the alias refers to. Can be any of |
|
The name of the alias. This is a required option. |
|
An optional routing that can be associated with an alias. |
|
An optional filter that can be associated with an alias. |
You can also use the plural _aliases
.
Examples:
edit- Adding time based alias
-
curl -XPUT 'localhost:9200/logs_201305/_alias/2013'
- Adding a user alias
-
First create the index and add a mapping for the
user_id
field:curl -XPUT 'localhost:9200/users' -d '{ "mappings" : { "user" : { "properties" : { "user_id" : {"type" : "integer"} } } } }'
Then add the alias for a specific user:
curl -XPUT 'localhost:9200/users/_alias/user_12' -d '{ "routing" : "12", "filter" : { "term" : { "user_id" : 12 } } }'
Aliases during index creation
editAliases can also be specified during index creation:
curl -XPUT localhost:9200/logs_20142801 -d '{ "mappings" : { "type" : { "properties" : { "year" : {"type" : "integer"} } } }, "aliases" : { "current_day" : {}, "2014" : { "filter" : { "term" : {"year" : 2014 } } } } }'
Delete aliases
editThe rest endpoint is: /{index}/_alias/{name}
where
|
|
|
|
Alternatively you can use the plural _aliases
. Example:
curl -XDELETE 'localhost:9200/users/_alias/user_12'
Retrieving existing aliases
editThe get index alias api allows to filter by alias name and index name. This api redirects to the master and fetches the requested index aliases, if available. This api only serialises the found index aliases.
Possible options:
|
The index name to get aliases for. Partially names are supported via wildcards, also multiple index names can be specified separated with a comma. Also the alias name for an index can be used. |
|
The name of alias to return in the response. Like the index option, this option supports wildcards and the option the specify multiple alias names separated by a comma. |
|
What to do is an specified index name doesn’t
exist. If set to |
The rest endpoint is: /{index}/_alias/{alias}
.
For future versions of Elasticsearch, the default Multiple Indices options will error if a requested index is unavailable. This is to bring this API in line with the other indices GET APIs
Examples:
editAll aliases for the index users:
curl -XGET 'localhost:9200/users/_alias/*'
Response:
{ "users" : { "aliases" : { "user_13" : { "filter" : { "term" : { "user_id" : 13 } }, "index_routing" : "13", "search_routing" : "13" }, "user_14" : { "filter" : { "term" : { "user_id" : 14 } }, "index_routing" : "14", "search_routing" : "14" }, "user_12" : { "filter" : { "term" : { "user_id" : 12 } }, "index_routing" : "12", "search_routing" : "12" } } } }
All aliases with the name 2013 in any index:
curl -XGET 'localhost:9200/_alias/2013'
Response:
{ "logs_201304" : { "aliases" : { "2013" : { } } }, "logs_201305" : { "aliases" : { "2013" : { } } } }
All aliases that start with 2013_01 in any index:
curl -XGET 'localhost:9200/_alias/2013_01*'
Response:
{ "logs_20130101" : { "aliases" : { "2013_01" : { } } } }
There is also a HEAD variant of the get indices aliases api to check if index aliases exist. The indices aliases exists api supports the same option as the get indices aliases api. Examples:
curl -XHEAD -i 'localhost:9200/_alias/2013' curl -XHEAD -i 'localhost:9200/_alias/2013_01*' curl -XHEAD -i 'localhost:9200/users/_alias/*'