OpenText Analytics Database 26.2.x – Cluster functions

Sql-Reference: CANCEL_REBALANCE_CLUSTER

Mon, 01 Jan 0001 00:00:00 +0000

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)

Sql-Reference: CHECK_CLUSTER_HEALTH

Mon, 01 Jan 0001 00:00:00 +0000

Checks the health of the cluster and aggregates the data in the HEALTH_WATCHDOG_BLOCKED_TRANSACTIONS view.

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

Behavior type

Immutable

Syntax

SELECT CHECK_CLUSTER_HEALTH();

Example

=> select check_cluster_health();
                                     check_cluster_health                                                                                                             
-----------------------------------------------------------------------------------------------------------------------
 Cluster State: Not Healthy.
Reason: GCLX QUEUE BLOAT
Description: GCLX queue is too large.
Number of blocked transactions: 2
Hint: Try to resubmit request later or Tune the value of the database parameter GCLXBlockParameter to proceed.

(1 row)

-- On resolving
verticadb21249=> select check_cluster_health();
   check_cluster_health   
--------------------------
 Cluster State: Healthy.

(1 row)

Sql-Reference: DISABLE_LOCAL_SEGMENTS

Mon, 01 Jan 0001 00:00:00 +0000

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

Volatile

Syntax

DISABLE_LOCAL_SEGMENTS()

Privileges

Superuser

Examples

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

Sql-Reference: ENABLE_ELASTIC_CLUSTER

Mon, 01 Jan 0001 00:00:00 +0000

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

Volatile

Syntax

ENABLE_ELASTIC_CLUSTER()

Privileges

Superuser

Examples

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

Sql-Reference: ENABLE_LOCAL_SEGMENTS

Mon, 01 Jan 0001 00:00:00 +0000

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

Volatile

Syntax

ENABLE_LOCAL_SEGMENTS()

Privileges

Superuser

Examples

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

Sql-Reference: REALIGN_CONTROL_NODES

Mon, 01 Jan 0001 00:00:00 +0000

Causes OpenText™ Analytics Database to re-evaluate which nodes in the cluster or subcluster are control nodes and which nodes are assigned to them as dependents when large cluster is enabled. Call this function after altering fault groups in an Enterprise Mode database, or changing the number of control nodes in either database mode. After calling this function, query the V_CATALOG.CLUSTER_LAYOUT system table to see the proposed new layout for nodes in the cluster. You must also take additional steps before the new control node assignments take effect. See Changing the number of control nodes and realigning for details.

Note

In database versions prior to 10.0.1, control node assignments weren't restricted to be within the same Eon Mode subcluster. If you attempt to realign control nodes in a subcluster whose control nodes have dependents in other subclusters, this function returns an error. In this case, you must realign the control nodes in those other subclusters first. Realigning the other subclusters fixes the cross-subcluster dependencies, allowing you to realign the control nodes in the original subcluster you attempted to realign.

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

Behavior type

Volatile

Syntax

In Enterprise Mode:

REALIGN_CONTROL_NODES()

In Eon Mode:

REALIGN_CONTROL_NODES('subcluster_name')

Parameters

subcluster_name: The name of the subcluster where you want to realign control nodes. Only the nodes in this subcluster are affected. Other subclusters are unaffected. Only allowed when the database is running in Eon Mode.

Privileges

Superuser

Examples

In an Enterprise Mode database, choose control nodes from all nodes and assign the remaining nodes to a control node:

=> SELECT REALIGN_CONTROL_NODES();

In an Eon Mode database, re-evaluate the control node assignments in the subcluster named analytics:

=> SELECT REALIGN_CONTROL_NODES('analytics');

Sql-Reference: REBALANCE_CLUSTER

Mon, 01 Jan 0001 00:00:00 +0000

Rebalances the database cluster synchronously as a session foreground task. REBALANCE_CLUSTER returns only after the rebalance operation is complete. If the current session ends, the operation immediately aborts. To rebalance the cluster as a background task, call START_REBALANCE_CLUSTER.

On large cluster arrangements, you typically call REBALANCE_CLUSTER in a flow (see Changing the number of control nodes and realigning). After you change the number and distribution of control nodes (spread hosts), run REBALANCE_CLUSTER to achieve fault tolerance.

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

Tip

By default, before performing a rebalance, Vertica queries system tables to compute the size of all projections involved in the rebalance task. This query can add significant overhead to the rebalance operation. To disable this query, set projection configuration parameter RebalanceQueryStorageContainers to 0.

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

Behavior type

Volatile

Syntax

REBALANCE_CLUSTER()

Privileges

Superuser

Examples

=> SELECT REBALANCE_CLUSTER();
REBALANCE_CLUSTER
-------------------
 REBALANCED
(1 row)

Sql-Reference: RELOAD_SPREAD

Mon, 01 Jan 0001 00:00:00 +0000

Updates cluster changes to the catalog's Spread configuration file. These changes include:

New or realigned control nodes
New Spread hosts or fault group
New or dropped cluster nodes

This function is often used in a multi-step process for large and elastic cluster arrangements. Calling it might require you to restart the database. You must then rebalance the cluster to realize fault tolerance. For details, see Defining and Realigning Control Nodes.

Caution

In an Eon Mode database, using this function could result in the database becoming read-only. Nodes may become disconnected after you call this function. If the database no longer has primary shard coverage without these nodes, it goes into read-only mode to maintain data integrity. Once the nodes rejoin the cluster, the database will resume normal operation. See Maintaining Shard Coverage.

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

Behavior type

Volatile

Syntax

RELOAD_SPREAD( true )

Parameters

true: Updates cluster changes related to control message responsibilities to the Spread configuration file.

Privileges

Superuser

Examples

Update the cluster with changes to control messaging:

=> SELECT reload_spread(true);
 reload_spread
---------------
 reloaded
(1 row)

Sql-Reference: SET_CONTROL_SET_SIZE

Mon, 01 Jan 0001 00:00:00 +0000

Sets the number of control nodes that participate in the spread service when large cluster is enabled. If the database is running in Enterprise Mode, this function sets the number of control nodes for the entire database cluster. If the database is running in Eon Mode, this function sets the number of control nodes in the subcluster you specify. See Large cluster for more information.

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

Behavior type

Volatile

Syntax

In Enterprise Mode:

SET_CONTROL_SET_SIZE( control_nodes )

In Eon Mode:

SET_CONTROL_SET_SIZE('subcluster_name', control_nodes )

Parameters

subcluster_name

The name of the subcluster where you want to set the number of control nodes. Only allowed when the database is running in Eon Mode.

control_nodes

The number of control nodes to assign to the cluster (when in Enterprise Mode) or subcluster (when in Eon Mode). Value can be one of the following:

Positive integer value: OpenText™ Analytics Database assigns the number of control nodes you specify to the cluster or subcluster. This value can be larger than the current node count. This value cannot be larger than 120 (the maximum number of control nodes for a database). In Eon Mode, the total of this value plus the number of control nodes set for all other subclusters cannot be more than 120.
-1: Makes every node in the cluster or subcluster into control nodes. This value effectively disables large cluster for the cluster or subcluster.

Privileges

Superuser

Examples

In an Enterprise Mode database, set the number of control nodes for the entire cluster to 5:

=> SELECT set_control_set_size(5);
 SET_CONTROL_SET_SIZE
----------------------
 Control size set
(1 row)

Sql-Reference: SET_SCALING_FACTOR

Mon, 01 Jan 0001 00:00:00 +0000

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

Volatile

Syntax

SET_SCALING_FACTOR( factor )

Parameters

factor: An integer value between 1 and 32. OpenText™ Analytics Database 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 OpenText™ Analytics Database 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)

Sql-Reference: START_REBALANCE_CLUSTER

Mon, 01 Jan 0001 00:00:00 +0000

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

Volatile

Syntax

START_REBALANCE_CLUSTER()

Privileges

Superuser

Examples

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

OpenText Analytics Database 26.2.x – Cluster functions

Sql-Reference: CANCEL_REBALANCE_CLUSTER

Behavior type

Syntax

Privileges

Examples

See also

Sql-Reference: CHECK_CLUSTER_HEALTH

Behavior type

Syntax

Example

See also

Sql-Reference: DISABLE_LOCAL_SEGMENTS

Behavior type

Syntax

Privileges

Examples

Sql-Reference: ENABLE_ELASTIC_CLUSTER

Behavior type

Syntax

Privileges

Examples

Sql-Reference: ENABLE_LOCAL_SEGMENTS

Behavior type

Syntax

Privileges

Examples

Sql-Reference: REALIGN_CONTROL_NODES

Note

Behavior type

Syntax

Parameters

Privileges

Examples

See also

Sql-Reference: REBALANCE_CLUSTER

Tip

Behavior type

Syntax

Privileges

Examples

Sql-Reference: RELOAD_SPREAD

Caution

Behavior type

Syntax

Parameters

Privileges

Examples

See also

Sql-Reference: SET_CONTROL_SET_SIZE

Behavior type

Syntax

Parameters

Privileges

Examples

See also

Sql-Reference: SET_SCALING_FACTOR

Behavior type

Syntax

Parameters

Privileges

Best practices

Examples

Sql-Reference: START_REBALANCE_CLUSTER

Behavior type

Syntax

Privileges

Examples

See also