Vertica – Projection Refreshes

Before a new projection can go live, it needs to be refreshed from the raw data.A refresh transfers data to projections that are not able to participate in query execution due to missing or out-of-date data.

START_REFRESH()

Several rules to being able to do an asynchronous refresh mainly (Full details here)

  • All nodes must be up in order to start a refresh..
  • Runs in the background asynchronously
SELECT START_REFRESH();

REFRESH()

Slightly different in that it performs a synchronous, optionally-targeted refresh of a specified table’s projections. (Full details here)

select refresh('schema.table');:

MONITORING

select node_name, projection_name, refresh_status, refresh_start 
from projection_refreshes where anchor_table_name = 'table';

More detail for refreshing projections

select node_name, projection_name, refresh_status, 
refresh_start, refresh_duration_sec, runtime_priority 
from projection_refreshes 
where is_executing = 't';
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