11[[cluster-update-settings]]
22== Cluster Update Settings
33
4- Allows to update cluster wide specific settings. Settings updated can
5- either be persistent (applied across restarts) or transient (will not
6- survive a full cluster restart). Here is an example:
4+ Use this API to review and change cluster-wide settings.
5+
6+ To review cluster settings:
7+
8+ [source,js]
9+ --------------------------------------------------
10+ GET /_cluster/settings
11+ --------------------------------------------------
12+ // CONSOLE
13+
14+ Updates to settings can be persistent, meaning they apply across restarts, or transient, where they don't
15+ survive a full cluster restart. Here is an example of a persistent update:
716
817[source,js]
918--------------------------------------------------
@@ -16,7 +25,7 @@ PUT /_cluster/settings
1625--------------------------------------------------
1726// CONSOLE
1827
19- Or :
28+ This update is transient :
2029
2130[source,js]
2231--------------------------------------------------
@@ -29,8 +38,7 @@ PUT /_cluster/settings?flat_settings=true
2938--------------------------------------------------
3039// CONSOLE
3140
32- The cluster responds with the settings updated. So the response for the
33- last example will be:
41+ The response to an update returns the changed setting, as in this response to the transient example:
3442
3543[source,js]
3644--------------------------------------------------
@@ -44,11 +52,14 @@ last example will be:
4452--------------------------------------------------
4553// TESTRESPONSE[s/\.\.\./"acknowledged": true,/]
4654
47- Resetting persistent or transient settings can be done by assigning a
48- `null` value. If a transient setting is reset, the persistent setting
49- is applied if available. Otherwise Elasticsearch will fallback to the setting
50- defined at the configuration file or, if not existent, to the default
51- value. Here is an example:
55+ You can reset persistent or transient settings by assigning a
56+ `null` value. If a transient setting is reset, the first one of these values that is defined is applied:
57+
58+ * the persistent setting
59+ * the setting in the configuration file
60+ * the default value.
61+
62+ This example resets a setting:
5263
5364[source,js]
5465--------------------------------------------------
@@ -61,8 +72,7 @@ PUT /_cluster/settings
6172--------------------------------------------------
6273// CONSOLE
6374
64- Reset settings will not be included in the cluster response. So
65- the response for the last example will be:
75+ The response does not include settings that have been reset:
6676
6777[source,js]
6878--------------------------------------------------
@@ -74,8 +84,8 @@ the response for the last example will be:
7484--------------------------------------------------
7585// TESTRESPONSE[s/\.\.\./"acknowledged": true,/]
7686
77- Settings can also be reset using simple wildcards. For instance to reset
78- all dynamic `indices.recovery` setting a prefix can be used :
87+ You can also reset settings using wildcards. For example, to reset
88+ all dynamic `indices.recovery` settings :
7989
8090[source,js]
8191--------------------------------------------------
@@ -88,25 +98,19 @@ PUT /_cluster/settings
8898--------------------------------------------------
8999// CONSOLE
90100
91- Cluster wide settings can be returned using:
92-
93- [source,js]
94- --------------------------------------------------
95- GET /_cluster/settings
96- --------------------------------------------------
97- // CONSOLE
98101
99102[float]
100- === Precedence of settings
103+ === Order of Precedence
104+
105+ The order of precedence for cluster settings is:
101106
102- Transient cluster settings take precedence over persistent cluster settings,
103- which take precedence over settings configured in the `elasticsearch.yml`
104- config file.
107+ 1. transient cluster settings
108+ 2. persistent cluster settings
109+ 3. settings in the `elasticsearch.yml` configuration file.
105110
106- For this reason it is preferrable to use the `elasticsearch.yml` file only
107- for local configurations, and set all cluster-wider settings with the
111+ It's best to use the `elasticsearch.yml` file only
112+ for local configurations, and set all cluster-wide settings with the
108113`settings` API.
109114
110- A list of dynamically updatable settings can be found in the
111- <<modules,Modules>> documentation.
115+ You can find the list of settings that you can dynamically update in <<modules,Modules>>.
112116
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