Re: epoch and timezone changed bevior

On 09/24/2015 03:42 PM, Willy-Bas Loos wrote:
> Hi,
>
> We're upgrading a database from 8.4 to 9.4
> The web developer complains that the timestamps are suddenly 2 hours late.
> We are in GMT+02.
> The issue would go away if we cast the postgres timestamps to timestamp
> WITH timezone. It works in pg8.4 and 9.4
>
> He told me that PHP always uses timezones, so i tried to reproduce it
> without the application layer.
> Since PHP always uses a timezone, the first part of the query always
> converts to "with time zone', it is what i presume PHP is doing.
>
> select timestamp with time zone 'epoch' + extract(epoch from
> now()::timestamp) * interval '1 second'-now(),substr(version(), 12, 3)
> --> 02:00:00 9.4
> --> 00:00:00 8.4
>
> select timestamp with time zone 'epoch' + extract(epoch from
> now()::timestamp WITH TIME ZONE) * interval '1 second' -
> now(),substr(version(), 12, 3)
> --> 00:00:00 9.4
> --> 00:00:00 8.4
>
> Is there a reason for this change of behavior between 8.4 and 9.* ?

Yes. As of 9.2, the server's timezone is set when the database is
initialized. See the following commit message:
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=ca4af308c32d03db5fbacb54d6e583ceb904f268
--
Vik Fearing +33 6 46 75 15 36
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support