From: Tom Lane <tgl@sss.pgh.pa.us>
To: Vik Fearing <vik@postgresfriends.org>
cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>,
        Thomas Munro <thomas.munro@gmail.com>,
        Petr Fedorov <petr.fedorov@phystech.edu>,
        pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Since '2001-09-09 01:46:40'::timestamp microseconds are lost when
 extracting epoch
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Comments: In-reply-to Vik Fearing <vik@postgresfriends.org>
	message dated "Mon, 25 May 2020 18:52:01 +0200"
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Date: Mon, 25 May 2020 13:07:30 -0400
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Vik Fearing <vik@postgresfriends.org> writes:
> On 5/25/20 6:40 PM, Tom Lane wrote:
>> While at it, maybe we could
>> fix things so that the syntax reverse-lists the same way instead
>> of injecting Postgres-isms...

> I'm not sure what this means.

This:

regression=3D# create view myview as select extract(year from current_time=
stamp) as y;
CREATE VIEW
regression=3D# \d+ myview
...
View definition:
 SELECT date_part('year'::text, CURRENT_TIMESTAMP) AS y;

What had been a 100% spec-compliant view definition is now quite
Postgres-specific.  I fixed some similar problems in 0bb51aa96 (before
that, the CURRENT_TIMESTAMP part would've reverse-listed differently
too); but I didn't tackle EXTRACT(), SUBSTRING(), and other cases.

I'm not claiming that we really need to fix all of those.  But if we are
going to pick nits about which data type EXTRACT() returns then I think
it's legit to worry about its reverse-list representation at the same
time ... especially if we must touch the grammar's translation anyway.

			regards, tom lane