Example:
dbadmin=> \x
Expanded display is on.
dbadmin=> SELECT sysdate,
dbadmin-> DATE_TRUNC('MILLENNIUM', sysdate) AS BY_MILLENNIUM,
dbadmin-> DATE_TRUNC('CENTURY', sysdate) AS BY_CENTURY,
dbadmin-> DATE_TRUNC('DECADE', sysdate) AS BY_DECADE,
dbadmin-> DATE_TRUNC('YEAR', sysdate) AS BY_YEAR,
dbadmin-> DATE_TRUNC('QUARTER', sysdate) AS BY_QUARTER,
dbadmin-> DATE_TRUNC('MONTH', sysdate) AS BY_MONTH,
dbadmin-> DATE_TRUNC('DAY', sysdate) AS BY_DAY,
dbadmin-> DATE_TRUNC('HOUR', sysdate) AS BY_HOUR,
dbadmin-> DATE_TRUNC('MINUTE', sysdate) AS BY_MINUTE,
dbadmin-> DATE_TRUNC('SECOND', sysdate) AS BY_SECOND,
dbadmin-> DATE_TRUNC('MILLISECONDS', sysdate) AS BY_MILLISECONDS,
dbadmin-> DATE_TRUNC('MICROSECONDS', sysdate) AS BY_MICROSECONDS;
-[ RECORD 1 ]---+---------------------------
sysdate | 2019-04-04 16:34:32.705186
BY_MILLENNIUM | 2001-01-01 00:00:00
BY_CENTURY | 2001-01-01 00:00:00
BY_DECADE | 2010-01-01 00:00:00
BY_YEAR | 2019-01-01 00:00:00
BY_QUARTER | 2019-04-01 00:00:00
BY_MONTH | 2019-04-01 00:00:00
BY_DAY | 2019-04-04 00:00:00
BY_HOUR | 2019-04-04 16:00:00
BY_MINUTE | 2019-04-04 16:34:00
BY_SECOND | 2019-04-04 16:34:32
BY_MILLISECONDS | 2019-04-04 16:34:32.705
BY_MICROSECONDS | 2019-04-04 16:34:32.705186
So did the current Millennium begin on January 1, 2000 or January 1, 2001? Let’s ask Vertica!
dbadmin=> SELECT DATE_TRUNC('MILLENNIUM', '01/01/2000'::TIMESTAMP),
dbadmin-> DATE_TRUNC('MILLENNIUM', '01/01/2001'::TIMESTAMP);
DATE_TRUNC | DATE_TRUNC
---------------------+---------------------
1001-01-01 00:00:00 | 2001-01-01 00:00:00
(1 row)
Helpful Link:
https://www.vertica.com/docs/latest/HTML/Content/Authoring/SQLReferenceManual/Functions/Date-Time/DATE_TRUNC.htm
Have fun!
About the Author
James Knicely
Vertica Field Chief Technologist
I've had the privilege of working with many database technologies in my career. But after being introduced to Vertica in May of 2011 as a client, I was hooked on the new technology after witnessing a query run in milliseconds that had previously ran for hours on the legacy database we had in place. It was then that I knew I wanted to eventually join the Vertica team, and 4 years later I did! I am currently a Vertica evangelist and am ready to help you get on board! Please feel free to reach out to me with any questions you have about Vertica and make sure to follow my Vertica Quick Tips!
