The Vertica Database Forums

I've been trying to develop a report , got each table name and last query date using below query
SELECT
anchor_table_id,
max( query_start_timestamp ) as last_access
FROM
v_monitor.projection_usage
group by
1
and I've noticed that not all tables got an entry in this table although i've performed a query against them , anyone experienced the same issue or can suggest another query .

Systems tables are really views on top of Data Collector tables. So the time span for the data in the system table is dependent upon the retention of the data in the DC tables. You can see the current effective retention for each table on each node in the DATA_COLLECTOR table. You can increase the retention using a time-based policy (set_data_collector_policy()), as long as you also provide enough disk space to satisfy that time period.

—Sharon

You can read my post on setting a time based collection policy here.