Using below query, you will get the size of Vertica tables.
SELECT anchor_table_schema,
anchor_table_name,
SUM(used_bytes) / (1024/1024/ * 1024/ * 1024) AS TABLE_SIZE_GB
FROM v_monitor.projection_storage
GROUP BY anchor_table_schema,
anchor_table_name
order by sum(used_bytes) desc;
Check out the most important queries to check table size
https://www.orahow.com/2018/06/how-to-check-size-of-tables-in-vertica.html