SQL: change the default precision for CURRENT_TIMESTAMP

[astefan]

For CURRENT_TIMESTAMP function at the moment we have the following documentation example:

SELECT CURRENT_TIMESTAMP AS result;

         result
------------------------
2018-12-12T14:48:52.448Z

Which isn't entirely correct, because the lack of a precision, defaults it to 0. The 0 precision means no milliseconds are returned.

[elasticmachine]

Pinging @elastic/es-search

[matriv]

In my opinion we should change the behaviour, as for example PostgreSQL behaves like:

postgres=# select current_timestamp;
       current_timestamp
-------------------------------
 2019-02-22 10:55:28.484944+02
(1 row)

oracle and sqlserver seems to behave also the same way: https://docs.microsoft.com/en-us/sql/t-sql/functions/current-timestamp-transact-sql?view=sql-server-2017#a-get-the-current-system-date-and-time
http://www.oracletutorial.com/oracle-date-functions/oracle-current_timestamp/

MySQL on the other hand seems to return by default only seconds.

[bpintea]

I would also favor one of the two solutions: present meaningful millis with precision 3, or stop at seconds with default precision 0.

[costin]

It seems to me that there's no clear rule regarding precision and it's to the operating system/implementation. On one hand I like the default precision (0 in this case) however I can see how, based on the existing behavior, the millis are expected hence why I propose to change, for current_timestamp, the precision to 3.

[astefan]

master (8.0.0): dbb9331
7.x (7.1.0): 542e2c5
7.0 (7.0.0): 3a84ccc
6.7 (6.7.0): 5dc5c6a