OpenSearch/docs/reference/search/request/preference.asciidoc
Jason Tedor d09d89f8c5 Remove only node preference
This commit removes the search preference _only_node as the same
functionality can be obtained by using the search preference
_only_nodes. This commit also adds a test that ensures that _only_nodes
will continue to support specifying node IDs.

Relates #18875
2016-06-17 15:27:46 -04:00

66 lines
1.9 KiB
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[[search-request-preference]]
=== Preference
Controls a `preference` of which shard replicas to execute the search
request on. By default, the operation is randomized between the shard
replicas.
The `preference` is a query string parameter which can be set to:
[horizontal]
`_primary`::
The operation will go and be executed only on the primary
shards.
`_primary_first`::
The operation will go and be executed on the primary
shard, and if not available (failover), will execute on other shards.
`_replica`::
The operation will go and be executed only on a replica shard.
`_replica_first`::
The operation will go and be executed only on a replica shard, and if
not available (failover), will execute on other shards.
`_local`::
The operation will prefer to be executed on a local
allocated shard if possible.
`_prefer_nodes:abc,xyz`::
Prefers execution on the nodes with the provided
node ids (`abc` or `xyz` in this case) if applicable.
`_shards:2,3`::
Restricts the operation to the specified shards. (`2`
and `3` in this case). This preference can be combined with other
preferences but it has to appear first: `_shards:2,3;_primary`
`_only_nodes`::
Restricts the operation to nodes specified in node specification
https://www.elastic.co/guide/en/elasticsearch/reference/current/cluster.html
Custom (string) value::
A custom value will be used to guarantee that
the same shards will be used for the same custom value. This can help
with "jumping values" when hitting different shards in different refresh
states. A sample value can be something like the web session id, or the
user name.
For instance, use the user's session ID to ensure consistent ordering of results
for the user:
[source,js]
------------------------------------------------
GET /_search?preference=xyzabc123
{
"query": {
"match": {
"title": "elasticsearch"
}
}
}
------------------------------------------------
// CONSOLE