Sub-second EXTRACT behaves differently from postgres

[habnabit]

On postgres v11.5 (but I'm pretty sure this has always behaved as such):

=# select current_timestamp, extract(microseconds from current_timestamp);
       current_timestamp       | date_part
-------------------------------+-----------
 2019-09-11 18:03:45.553972+00 |  45553972

On cockroachdb v19.1.3:

> select current_timestamp, extract(microseconds from current_timestamp);
         current_timestamp         | extract
+----------------------------------+---------+
  2019-09-11 18:03:35.056128+00:00 |   56128

The postgres documentation for datetime functions agrees with the postgres behavior: sub-second EXTRACT gives the full seconds as part of the extracted value. "Note that this includes full seconds."

I have to say I prefer the cockroachdb behavior, but it should probably be aligned with the postgres behavior.

[habnabit]

Oh, I should mention.. I discovered this because also extract(epoch ..) is a float with sub-second precision on postgres but an integer on cockroachdb.