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List:       pgsql-bugs
Subject:    Re: [BUGS] BUG #7888: Small issue on wiki page Round time
From:       Bruce Momjian <bruce () momjian ! us>
Date:       2013-02-18 14:26:54
Message-ID: 20130218142654.GM12030 () momjian ! us
[Download RAW message or body]


It is a wiki, so you can easily get an account and make the change
yourself.  Thanks.

---------------------------------------------------------------------------

On Sun, Feb 17, 2013 at 07:14:00PM +0000, spm@spamik.cz wrote:
> The following bug has been logged on the website:
> 
> Bug reference:      7888
> Logged by:          Jan Krajdl
> Email address:      spm@spamik.cz
> PostgreSQL version: Unsupported/Unknown
> Operating system:   all
> Description:        
> 
> Hi,
> 
> I have found small issue on this wiki page:
> http://wiki.postgresql.org/wiki/Round_time
> 
> There is mistake in "alternative approach" function - select
> '1970-01-01'::timestamptz results in timestamp '1970-01-01 00:00:00' with
> local timezone. But function is using it as a start of epoch which was same
> time but in timezone GMT. If you use this function and you have postgres
> server in non GMT timezone, rounded results are in GMT timezone but they
> have timezone information about local timezone.
> 
> I'm quite noob with postgres but I tried to fix it and it looks that this
> code:
> 
> CREATE FUNCTION date_round(base_date timestamptz, round_interval INTERVAL)
> RETURNS timestamptz AS $BODY$
> SELECT TIMESTAMP WITH TIME ZONE 'epoch' + (EXTRACT(epoch FROM $1)::INTEGER +
> EXTRACT(epoch FROM $2)::INTEGER / 2)
>                 / EXTRACT(epoch FROM $2)::INTEGER * EXTRACT(epoch FROM
> $2)::INTEGER * INTERVAL '1 second';
> $BODY$ LANGUAGE SQL STABLE;
> 
> is doing it better - returned time looks correct. So if you want you can
> update this page.
> 
> Regards,
> 
> -- 
> Jan Krajdl
> 
> 
> 
> -- 
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-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +


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