[[indices-update-settings]]
== Update Indices Settings

Change specific index level settings in real time.

The REST endpoint is `/_settings` (to update all indices) or
`{index}/_settings` to update one (or more) indices settings. The body
of the request includes the updated settings, for example:

[source,js]
--------------------------------------------------
{
    "index" : {
        "number_of_replicas" : 4
    } 
}
--------------------------------------------------

The above will change the number of replicas to 4 from the current
number of replicas. Here is a curl example:

[source,js]
--------------------------------------------------
curl -XPUT 'localhost:9200/my_index/_settings' -d '
{
    "index" : {
        "number_of_replicas" : 4
    } 
}'
--------------------------------------------------

[WARNING]
========================
When changing the number of replicas the index needs to be open. Changing
the number of replicas on a closed index might prevent the index to be opened correctly again.
========================

Below is the list of settings that can be changed using the update
settings API:

`index.number_of_replicas`::
    The number of replicas each shard has.

`index.auto_expand_replicas` (string)::
    Set to a dash delimited lower and upper bound (e.g. `0-5`)
    or one may use `all` as the upper bound (e.g. `0-all`), or `false` to disable it.

`index.blocks.read_only`::
    Set to `true` to have the index read only, `false` to allow writes
    and metadata changes.

`index.blocks.read`::
    Set to `true` to disable read operations against the index.

`index.blocks.write`::
    Set to `true` to disable write operations against the index.

`index.blocks.metadata`::
    Set to `true` to disable metadata operations against the index.

`index.refresh_interval`::
    The async refresh interval of a shard.

`index.index_concurrency`::
    experimental[] Defaults to `8`.

`index.translog.flush_threshold_ops`::
    When to flush based on operations.

`index.translog.flush_threshold_size`::
    When to flush based on translog (bytes) size.

`index.translog.flush_threshold_period`::
    When to flush based on a period of not flushing.

`index.translog.disable_flush`::
    Disables flushing. Note, should be set for a short
    interval and then enabled.

`index.cache.filter.max_size`::
    The maximum size of filter cache (per segment in shard).
    Set to `-1` to disable.

`index.cache.filter.expire`::
    experimental[] The expire after access time for filter cache.
    Set to `-1` to disable.

`index.gateway.snapshot_interval`::
    experimental[] The gateway snapshot interval (only applies to shared
    gateways). Defaults to 10s.

<<index-modules-merge,merge policy>>::
    All the settings for the merge policy currently configured.
    A different merge policy can't be set.

`index.merge.scheduler.*`::
    experimental[] All the settings for the merge scheduler.

`index.routing.allocation.include.*`::
    A node matching any rule will be allowed to host shards from the index.

`index.routing.allocation.exclude.*`::
    A node matching any rule will NOT be allowed to host shards from the index.

`index.routing.allocation.require.*`::
    Only nodes matching all rules will be allowed to host shards from the index.

`index.routing.allocation.disable_allocation`::
    Disable allocation. Defaults to `false`. Deprecated in favour for `index.routing.allocation.enable`.

`index.routing.allocation.disable_new_allocation`::
    Disable new allocation. Defaults to `false`. Deprecated in favour for `index.routing.allocation.enable`.

`index.routing.allocation.disable_replica_allocation`::
    Disable replica allocation. Defaults to `false`. Deprecated in favour for `index.routing.allocation.enable`.

`index.routing.allocation.enable`::
    Enables shard allocation for a specific index. It can be set to:
    * `all` (default) - Allows shard allocation for all shards.
    * `primaries` - Allows shard allocation only for primary shards.
    * `new_primaries` - Allows shard allocation only for primary shards for new indices.
    * `none` - No shard allocation is allowed.

`index.routing.rebalance.enable`::
    Enables shard rebalancing for a specific index. It can be set to:
    * `all` (default) - Allows shard rebalancing for all shards.
    * `primaries` - Allows shard rebalancing only for primary shards.
    * `replicas` - Allows shard rebalancing only for replica shards.
    * `none` - No shard rebalancing is allowed.

`index.routing.allocation.total_shards_per_node`::
    Controls the total number of shards (replicas and primaries) allowed to be allocated on a single node. Defaults to unbounded (`-1`).

`index.recovery.initial_shards`::
    When using local gateway a particular shard is recovered only if there can be allocated quorum shards in the cluster. It can be set to:
    * `quorum` (default)
    * `quorum-1` (or `half`)
    * `full`
    * `full-1`.
    * Number values are also supported, e.g. `1`.

`index.gc_deletes`::
    experimental[]

`index.ttl.disable_purge`::
    experimental[] Disables temporarily the purge of expired docs.

<<index-modules-store,store level throttling>>::
    All the settings for the store level throttling policy currently configured.

`index.translog.fs.type`::
    experimental[] Either `simple` or `buffered` (default).

`index.compound_format`::
    experimental[] See <<index-compound-format,`index.compound_format`>> in
    <<index-modules-settings>>.

`index.compound_on_flush`::
    experimental[] See <<index-compound-on-flush,`index.compound_on_flush>> in
    <<index-modules-settings>>.

<<index-modules-slowlog>>::
    All the settings for slow log.

`index.warmer.enabled`::
    See <<indices-warmers>>. Defaults to `true`.

[float]
[[bulk]]
=== Bulk Indexing Usage

For example, the update settings API can be used to dynamically change
the index from being more performant for bulk indexing, and then move it
to more real time indexing state. Before the bulk indexing is started,
use:

[source,js]
--------------------------------------------------
curl -XPUT localhost:9200/test/_settings -d '{
    "index" : {
        "refresh_interval" : "-1"
    } }'
--------------------------------------------------

(Another optimization option is to start the index without any replicas,
and only later adding them, but that really depends on the use case).

Then, once bulk indexing is done, the settings can be updated (back to
the defaults for example):

[source,js]
--------------------------------------------------
curl -XPUT localhost:9200/test/_settings -d '{
    "index" : {
        "refresh_interval" : "1s"
    } }'
--------------------------------------------------

And, an optimize should be called:

[source,js]
--------------------------------------------------
curl -XPOST 'http://localhost:9200/test/_optimize?max_num_segments=5'
--------------------------------------------------

[float]
[[update-settings-analysis]]
=== Updating Index Analysis

It is also possible to define new <<analysis,analyzers>> for the index.
But it is required to <<indices-open-close,close>> the index
first and <<indices-open-close,open>> it after the changes are made.

For example if `content` analyzer hasn't been defined on `myindex` yet
you can use the following commands to add it:

[source,js]
--------------------------------------------------
curl -XPOST 'localhost:9200/myindex/_close'

curl -XPUT 'localhost:9200/myindex/_settings' -d '{
  "analysis" : {
    "analyzer":{
      "content":{
        "type":"custom",
        "tokenizer":"whitespace"
      }
    }
  }
}'

curl -XPOST 'localhost:9200/myindex/_open'
--------------------------------------------------