Vertica In-active partitions

It is not always necessary to increase active partition count. Older partitions are not explicitly read-only, but Tuple Mover will work on inactive partitions with lower priority. The following query will find which partitions are "active" in the sense that they are being processed as "strata" in Tuple Mover:

SELECT p.node_name, p.partition_key, p.ros_id, p.ros_size_bytes, p.ros_row_count, ROS_container_count
FROM partitions p JOIN strata s ON p.partition_key = s.stratum_key AND p.node_name=s.node_name
WHERE p.projection_name = '<your_projection_name>' ORDER BY p.node_name, p.partition_key;

It will help to know what version of Vertica you are using, because Tuple Mover behavior changed a bit between major versions (7.x, 8.x, 9.x, 10.x)

Vertica version is 8.x

I'm not sure I understand the issue. Even data loaded into inactive partitions is available for query and will be processed through strata eventually. It is just not fully optimized at first. In Vertica 8.x, you can assign more resources to TM resource pool, then run SELECT DO_TM_TASK('mergeout'); and TM will start to merge out inactive partition data though it will take longer to process and the manual mergeout may take a noticeable amount of resources causing other jobs and queries to slow.