Cluster scaling functions

• 1: CANCEL_REBALANCE_CLUSTER
• 2: DISABLE_LOCAL_SEGMENTS
• 3: ENABLE_ELASTIC_CLUSTER
• 4: ENABLE_LOCAL_SEGMENTS
• 5: SET_SCALING_FACTOR
• 6: START_REBALANCE_CLUSTER

1 - CANCEL_REBALANCE_CLUSTER

Stops any rebalance task that is currently in progress or is waiting to execute.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Syntax

CANCEL_REBALANCE_CLUSTER()

Privileges

Superuser

Examples

=> SELECT CANCEL_REBALANCE_CLUSTER();
 CANCEL_REBALANCE_CLUSTER
--------------------------
 CANCELED
(1 row)

See also

• START_REBALANCE_CLUSTER
• REBALANCE_CLUSTER

2 - DISABLE_LOCAL_SEGMENTS

Disables local data segmentation, which breaks projections segments on nodes into containers that can be easily moved to other nodes. See Local data segmentation for details.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Syntax

DISABLE_LOCAL_SEGMENTS()

Privileges

Superuser

Examples

=> SELECT DISABLE_LOCAL_SEGMENTS();
 DISABLE_LOCAL_SEGMENTS
------------------------
 DISABLED
(1 row)

3 - ENABLE_ELASTIC_CLUSTER

Enables elastic cluster scaling, which makes enlarging or reducing the size of your database cluster more efficient by segmenting a node's data into chunks that can be easily moved to other hosts.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Syntax

ENABLE_ELASTIC_CLUSTER()

Privileges

Superuser

Examples

=> SELECT ENABLE_ELASTIC_CLUSTER();
 ENABLE_ELASTIC_CLUSTER
------------------------
 ENABLED
(1 row)

4 - ENABLE_LOCAL_SEGMENTS

Enables local storage segmentation, which breaks projections segments on nodes into containers that can be easily moved to other nodes. See Local data segmentation for more information.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Syntax

ENABLE_LOCAL_SEGMENTS()

Privileges

Superuser

Examples

=> SELECT ENABLE_LOCAL_SEGMENTS();
 ENABLE_LOCAL_SEGMENTS
-----------------------
 ENABLED
(1 row)

5 - SET_SCALING_FACTOR

Sets the scaling factor that determines the number of storage containers used when rebalancing the database and when using local data segmentation is enabled. See Cluster Scaling for details.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Syntax

SET_SCALING_FACTOR( factor )

Parameters

factor

An integer value between 1 and 32. Vertica uses this value to calculate the number of storage containers each projection is broken into when rebalancing or when local data segmentation is enabled.

Privileges

Superuser

Best practices

The scaling factor determines the number of storage containers that Vertica uses to store each projection across the database during rebalancing when local segmentation is enabled. When setting the scaling factor, follow these guidelines:

• The number of storage containers should be greater than or equal to the number of partitions multiplied by the number of local segments:

  num-storage-containers >= ( num-partitions * num-local-segments )

• Set the scaling factor high enough so rebalance can transfer local segments to satisfy the skew threshold, but small enough so the number of storage containers does not result in too many ROS containers, and cause ROS pushback. The maximum number of ROS containers (by default 1024) is set by configuration parameter ContainersPerProjectionLimit.

Examples

=> SELECT SET_SCALING_FACTOR(12);
 SET_SCALING_FACTOR
--------------------
 SET
(1 row)

6 - START_REBALANCE_CLUSTER

Asynchronously rebalances the database cluster as a background task. This function returns immediately after the rebalancing operation is complete. Rebalancing persists until the operation is complete, even if you close the current session or the database shuts down. In the case of shutdown, rebalancing resumes after the cluster restarts. To stop the rebalance operation, call CANCEL_REBALANCE_CLUSTER.

For detailed information about rebalancing tasks, see Rebalancing data across nodes.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Syntax

START_REBALANCE_CLUSTER()

Privileges

Superuser

Examples

=> SELECT START_REBALANCE_CLUSTER();
 START_REBALANCE_CLUSTER
-------------------------
 REBALANCING
(1 row)

See also