Purging ROS containers

Vertica periodically checks ROS storage containers to determine whether delete vectors are eligible for purge, as follows:.

Vertica periodically checks ROS storage containers to determine whether delete vectors are eligible for purge, as follows:

  1. Counts the number of aged-out delete vectors in each container—that is, delete vectors that are equal to or earlier than the ancient history mark (AHM) epoch.

  2. Calculates the percentage of aged-out delete vectors relative to the total number of records in the same ROS container.

  3. If this percentage exceeds the threshold set by configuration parameter PurgeMergeoutPercent (by default, 20 percent), Vertica automatically performs a mergeout on the ROS container that permanently removes all aged-out delete vectors. Vertica uses the TM resource pool's MAXCONCURRENCY setting to determine how many threads are available for the mergeout operation.

You can also manually purge all aged-out delete vectors from ROS containers with two Vertica meta-functions:

Both functions remove all aged-out delete vectors from ROS containers, regardless of how many are in a given container.