Horton

Re: Support for jsonpath .datetime() method

Alexander Korotkov <a.korotkov@postgrespro.ru>

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From: Alexander Korotkov <a.korotkov@postgrespro.ru>
To: Nikita Glukhov <n.gluhov@postgrespro.ru>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Liudmila Mantrova <l.mantrova@postgrespro.ru>, Anastasia Lubennikova <lubennikovaav@gmail.com>
Date: 2019-07-24T13:45:04Z
Lists: pgsql-hackers 
On Wed, Jul 24, 2019 at 1:50 AM Nikita Glukhov <n.gluhov@postgrespro.ru> wrote:
> So it's unclear what we should do:
>  - implement YY and RR strictly following the standard only in .datetime()
>  - fix YY implementation in to_date()/to_timestamp() and implement RR
>  - use our non-standard templates in .datetime()

Also it appears that according to standard .datetime() should treat
spaces and delimiters differently than our to_date()/to_timestamp().
It requires strict matching of spaces and delimiters in input and
format strings.  We don't have such behavior in both non-FX and FX
modes.  Also, standard doesn't define FX mode at all.  This rules
cover jsonpath .datetime() method and CAST(... FORMAT ...) – new cast
clause defined by standard.

So, I think due to reasons of compatibility it doesn't worth trying to
make behavior of our to_date()/to_timestamp() to fit requirements for
jsonpath .datetime() and CAST(... FORMAT ...).  I propose to leave
this functions as is (maybe add new patterns), but introduce another
datetime parsing mode, which would fit to the standard.  Opinions?

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

Commits

  1. Allow datetime values in JsonbValue

  2. Error suppression support for upcoming jsonpath .datetime() method

  3. Implement jsonpath .datetime() method

  4. Implement parse_datetime() function

  5. Implement standard datetime parsing mode

  6. Support for SSSSS datetime format pattern

  7. Support for FF1-FF6 datetime format patterns