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3.3

Runtime Configuration

The CrateDB cluster can be configured at runtime using the SET and RESET statement. See the Cluster Settings configuration section for details about the supported settings.

If SET is used with PERSISTENT the change will survive a cluster restart, if used with TRANSIENT the value will be restored to default or config file value on a restart:

cr> SET GLOBAL PERSISTENT stats.enabled = false;
SET OK, 1 row affected (... sec)

cr> select sys.cluster.settings['stats']['enabled'] from sys.cluster;
+------------------------------+
| settings['stats']['enabled'] |
+------------------------------+
| FALSE                        |
+------------------------------+
SELECT 1 row in set (... sec)

You can change multiple values at once:

cr> SET GLOBAL TRANSIENT stats.enabled = true,
... stats.jobs_log_size = 1024, stats.operations_log_size = 4096;
SET OK, 1 row affected (... sec)

cr> select settings['stats']['enabled'],
...   settings['stats']['jobs_log_size'],
...   settings['stats']['operations_log_size']
... from sys.cluster;
+-...------------+-...------------------+-...------------------------+
| ...['enabled'] | ...['jobs_log_size'] | ...['operations_log_size'] |
+-...------------+-...------------------+-...------------------------+
| TRUE           |                 1024 |                       4096 |
+-...------------+-...------------------+-...------------------------+
SELECT 1 row in set (... sec)

Its also possible to save a complete nested object of settings:

cr> SET GLOBAL TRANSIENT stats = {
...   jobs_log_size = 2048,
...   operations_log_size = 8192
... };
SET OK, 1 row affected (... sec)

cr> SELECT
...   settings['stats']['jobs_log_size'] AS jobs_size,
...   settings['stats']['operations_log_size'] AS op_size
... FROM sys.cluster;
+-----------+---------+
| jobs_size | op_size |
+-----------+---------+
|      2048 |    8192 |
+-----------+---------+
SELECT 1 row in set (... sec)

Using the RESET statement, a setting will be reset to either on node startup defined configuration file value or to its default value:

cr> RESET GLOBAL stats.enabled, stats.operations_log_size;
RESET OK, 1 row affected (... sec)

cr> SELECT
...   settings['stats']['jobs_log_size'] AS jobs_size,
...   settings['stats']['operations_log_size'] AS op_size
... FROM sys.cluster;
+-----------+---------+
| jobs_size | op_size |
+-----------+---------+
|      2048 |   10000 |
+-----------+---------+
SELECT 1 row in set (... sec)

RESET can also be done on objects:

cr> RESET GLOBAL stats;
RESET OK, 1 row affected (... sec)

cr> SELECT
...   settings['stats']['jobs_log_size'] AS jobs_size,
...   settings['stats']['operations_log_size'] AS op_size
... FROM sys.cluster;
+-----------+---------+
| jobs_size | op_size |
+-----------+---------+
|     10000 |   10000 |
+-----------+---------+
SELECT 1 row in set (... sec)