The EXTRACT function extracts one field from a DATE, TIME, TIMESTAMP or INTERVAL expression. Returns BIGINT for all fields other than SECOND. For SECOND it returns DECIMAL(5,3) and includes milliseconds.
EXTRACT(YEAR| MONTH| DAY| HOUR| MINUTE| SECOND FROM <datetime expression>| <interval expression>)
|EXTRACT(DAY FROM INTERVAL ‘2 3:4:5.678’ DAY TO SECOND)||2|
|EXTRACT(HOUR FROM INTERVAL ‘2 3:4:5.678’ DAY TO SECOND)||3|
|EXTRACT(MINUTE FROM INTERVAL ‘2 3:4:5.678’ DAY TO SECOND)||4|
|EXTRACT(SECOND FROM INTERVAL ‘2 3:4:5.678’ DAY TO SECOND)||5.678|
|EXTRACT(MINUTE FROM CURRENT_ROW_TIMESTAMP) where CURRENT_ROW_TIMESTAMP is 2016-09-23 04:29:26.234||29|
|EXTRACT (HOUR FROM CURRENT_ROW_TIMESTAMP) where CURRENT_ROW_TIMESTAMP is 2016-09-23 04:29:26.234||4|
EXTRACT can be used for conditioning data, as in the following function which returns a 30 minute floor when CURRENT_ROW_TIMESTAMP is input for p_time.
CREATE or replace FUNCTION FLOOR30MIN( p_time TIMESTAMP ) RETURNS TIMESTAMP CONTAINS SQL RETURNS NULL ON NULL INPUT RETURN floor(p_time to HOUR) + (( EXTRACT ( MINUTE FROM p_time ) / 30)* INTERVAL '30' MINUTE ) ;
You would implement this function using code along the following lines:
SELECT stream FLOOR30MIN( CURRENT_ROW_TIMESTAMP ) as ROWTIME, * from "MyStream" ) over (range current row ) as r
The code above assumes that you have previously created a stream called “MyStream.”