Date and Time Functions
The following built-in functions relate to dates and time.
Topics
Of these, the SQL extension CURRENT_ROW_TIMESTAMP is the most useful for a streaming context, because it gives you information about the times of streaming data as it emerges, not just when the query is run. This is a key difference between a streaming query and a traditional RDMS query: streaming queries remain "open," producing more data, so the timestamp for when the query was run does not offer good information.
LOCALTIMESTAMP, LOCALTIME, CURRENT_DATE, and CURRENT_TIMESTAMP all produce results which are set to values at the time the query first executes. Only CURRENT_ROW_TIMESTAMP generates a row with a unique timestamp (date and time) for each row.
A query run with LOCALTIMESTAMP (or CURRENT_TIMESTAMP or CURRENT_TIME) as one of the columns puts into all output rows the time the query is first run. If that column instead contains CURRENT_ROW_TIMESTAMP, each output row gets a newly-calculated value of TIME representing when that row was output.
To return a part (such as the day of the month) from a Datetime value, use EXTRACT
Time Zones
Amazon Kinesis Data Analytics runs in UTC. As a result, all time functions return time in UTC.
