REBALANCE_TABLE

Synchronously rebalances data in the specified table.

A rebalance operation performs the following tasks:

Distributes data based on:
- User-defined fault groups, if specified
- Large cluster automatic fault groups
Redistributes database projection data across all nodes.

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

Behavior type

Syntax

REBALANCE_TABLE('[[database.]schema.]table-name')

Parameters

schema: Database and schema. The default schema is public. If you specify a database, it must be the current database.
table-name: The table to rebalance.

Privileges

Superuser

When to rebalance

Rebalancing is useful or even necessary after you perform the following tasks:

Mark one or more nodes as ephemeral in preparation of removing them from the cluster.
Add one or more nodes to the cluster so that Vertica can populate the empty nodes with data.
Change the scaling factor of an elastic cluster, which determines the number of storage containers used to store a projection across the database.
Set the control node size or realign control nodes on a large cluster layout
Add nodes to or remove nodes from a fault group.

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.

Examples

The following command shows how to rebalance data on the specified table.

=> SELECT REBALANCE_TABLE('online_sales.online_sales_fact');
REBALANCE_TABLE
-------------------
 REBALANCED
(1 row)