Partition Mergeout

Vertica keeps data from different table partitions or partition groups separate on disk. The Tuple Mover adheres to this separation policy when it consolidates ROS containers. When a partition is first created, it typically has frequent data loads and requires regular activity from the Tuple Mover. As a partition ages, it commonly transitions to a mostly read-only workload and requires much less activity.

The Tuple Mover has two different policies for managing these different partition workloads:

• Active partition is the partition that was most recently created. The Tuple Mover uses a strata-based algorithm that seeks to minimize the number of times individual tuples undergo mergeout. A table's active partition count identifies how many partitions are active for that table.
• Inactive partitions are those that were not most recently created. The Tuple Mover consolidates ROS containers to a minimal set while avoiding merging containers whose size exceeds MaxMrgOutROSSizeMB.

For details on how the Tuple Mover identifies active partitions, see Active and Inactive Partitions.