I've a table with 2 billions records and I'm testing the "amazing" feature called "Flattened Table". My question is, can I monitor a refresh_columns? I'm waiting for 6 hours and don't know what's happening.
6 hours is lot of time . Do you have support contract ? if yes please open support case so that we can review further.
Yes Skamat we have contract. How can I send this problem to you. Today I spent 96,000 seconds in one refresh
Please open support ticket and include note to pass it to shrirang .
is there an answer to the original question? Is there a way to monitor progress of SELECT REFRESH_COLUMNS (with rebuild as the refresh method).
(The suggested answer is for projection refresh not column refresh)
Also if need to rebuild columns in multiple big tables will calling a single refresh_columns command with comma separated list of tables do the tables sequentially or in parallel?
I believe this DC table dc_refresh_columns contains that information.
That's correct! The dc_refresh_columns Data Collector table was introduced in Vertica 9.3:
dbadmin=> SELECT DISTINCT description FROM data_collector WHERE table_name = 'dc_refresh_columns';
History of all column refreshes
VER-68379 - Calls to REFRESH_COLUMNS can now be monitored in the new "dc_refresh_columns" table, which logs, for every call to REFRESH_COLUMNS, the time of the call, the name of the table, the refreshed columns, the mode used, the minimum and maximum key values, and the epoch.