Tuple Mover Parameters

These parameters control how the Tuple Mover operates.

Query the CONFIGURATION_PARAMETERS system table to determine what levels (node, session, user, database) are valid for a given parameter.

Parameters Description

ActivePartitionCount

Sets the number of active partitions. The active partitions are those most recently created. For example:

=> ALTER DATABASE DEFAULT SET ActivePartitionCount = 2;

For information about how the Tuple Mover treats active and inactive partitions during a mergeout operation, see Partition Mergeout.

Default: 1
CancelTMTimeout

When partition, copy table, and rebalance operations encounter a conflict with an internal Tuple Mover job, those operations attempt to cancel the conflicting Tuple Mover job. This parameter specifies the amount of time, in seconds, that the blocked operation waits for the Tuple Mover cancellation to take effect. If the operation is unable to cancel the Tuple Mover job within limit specified by this parameter, the operation displays an error and rolls back.

Default: 300
EnableTMOnRecoveringNode

Boolean, specifies whether Tuple Mover performs mergeout activities on nodes with a node state of RECOVERING. Enabling Tuple Mover reduces the number of ROS containers generated during recovery. Having fewer than 1024 ROS containers per projection allows Vertica to maintain optimal recovery performance.

Default: 1 (enabled)
MaxMrgOutROSSizeMB

Specifies in MB the maximum size of ROS containers that are candidates for mergeout operations. The Tuple Mover avoids merging ROS containers that are larger than this setting.

After a rebalance operation, Tuple Mover groups ROS containers in batches that are smaller than MaxMrgOutROSSizeMB. ROS containers that are larger than MaxMrgOutROSSizeMB are merged individually.

Default: -1 (no maximum limit)

MergeOutInterval

 Specifies in seconds how frequently the Tuple Mover checks the mergeout request queue for pending requests:
  1. If the queue contains mergeout requests, the Tuple Mover does nothing and goes back to sleep.
  2. If the queue is empty, the Tuple Mover:
    • Processes pending storage location move requests.
    • Checks for new unqueued purge requests and adds them to the queue.

    It then goes back to sleep.

Default: 600
PurgeMergeoutPercent

Specifies as a percentage the threshold of deleted records in a ROS container that invokes an automatic mergeout operation, to purge those records. Vertica only counts the number of 'aged-out' delete vectors—that is, delete vectors that are as 'old' or older than the ancient history mark (AHM) epoch.

This threshold applies to all ROS containers for non-partitioned tables. It also applies to ROS containers of all inactive partitions. In both cases, aged-out delete vectors are permanently purged from the ROS container.

This configuration parameter only applies to automatic mergeout operations. It does not apply to manual mergeout operations that are invoked by calling meta-functions DO_TM_TASK('mergeout') and PURGE.

Default: 20 (percent)