
You can monitor the progress of this phase of the COPY command via the data collector table DC_MERGE_EVENTS.
Example:
dbadmin->vmart@sandbox1=> SELECT DISTINCT component, description
dbadmin->vmart@sandbox1--> FROM data_collector
dbadmin->vmart@sandbox1--> WHERE table_name = 'dc_merge_events';
component | description
-------------+------------------------------------------------------------------------
MergeEvents | Events and progress of large sort that requires buffering data in disk
(1 row)
dbadmin=> COPY bf FROM '/home/dbadmin/bf.txt' DIRECT;
Rows Loaded
-------------
13000000
(1 row)
dbadmin=> SELECT time::TIME time, RIGHT(node_name, 1) node, event_description,
dbadmin-> rows_processed, rows_remaining, elapsed_time_seconds,
dbadmin-> remaining_time_seconds, percent_completed
dbadmin-> FROM dc_merge_events
dbadmin-> WHERE session_id = current_session()
dbadmin-> ORDER BY time;
time | node | event_description | rows_processed | rows_remaining | elapsed_time_seconds | remaining_time_seconds | percent_completed
-----------------+------+-----------------------------------------+----------------+----------------+----------------------+------------------------+-------------------
11:11:12.383548 | 1 | Started merge sort from chunks on disk. | 0 | 26000000 | 0 | -1 | 0
11:11:12.38366 | 1 | Running multi-phase merge. | 0 | 26000000 | 0 | -1 | 0
11:11:12.386755 | 1 | Running multi-phase merge. | 0 | 26000000 | 0 | -1 | 0
11:11:18.420824 | 1 | Running multi-phase merge. | 1149120 | 24850880 | 6 | 130 | 4
11:11:24.323535 | 1 | Running multi-phase merge. | 2298240 | 23701760 | 11 | 123 | 8
11:11:30.143029 | 1 | Running multi-phase merge. | 3447360 | 22552640 | 17 | 116 | 13
11:11:36.234431 | 1 | Running multi-phase merge. | 4596480 | 21403520 | 23 | 111 | 17
11:11:42.157763 | 1 | Running multi-phase merge. | 5745600 | 20254400 | 29 | 104 | 22
11:11:48.048463 | 1 | Running multi-phase merge. | 6894720 | 19105280 | 35 | 98 | 26
11:11:54.092553 | 1 | Running multi-phase merge. | 8043840 | 17956160 | 41 | 93 | 30
11:12:00.10969 | 1 | Running multi-phase merge. | 9192960 | 16807040 | 47 | 87 | 35
11:12:06.125121 | 1 | Running multi-phase merge. | 10342080 | 15657920 | 53 | 81 | 39
11:12:12.12821 | 1 | Running multi-phase merge. | 11491200 | 14508800 | 59 | 75 | 44
11:12:13.639376 | 1 | Merge has made progress. | 11778480 | 14221520 | 61 | 73 | 45
11:12:18.029708 | 1 | Running multi-phase merge. | 12640320 | 13359680 | 65 | 69 | 48
11:12:20.287778 | 1 | Final merge phase of multi-phase merge. | 13000000 | 13000000 | 67 | 67 | 50
11:12:40.262602 | 1 | DataTarget write finished. | 26000000 | 0 | 87 | 0 | 100
(17 rows)
Helpful Links:https://www.vertica.com/docs/latest/HTML/Content/Authoring/SQLReferenceManual/SystemTables/MONITOR/DATA_COLLECTOR.htm
https://www.vertica.com/docs/latest/HTML/Content/Authoring/AdministratorsGuide/Monitoring/Vertica/EnablingAndDisablingDataCollector.htm
Have fun!