Re: Default timezone changes in 9.1 - Mailing list pgsql-general

From Terence Ferraro
Subject Re: Default timezone changes in 9.1
Date
Msg-id CAEghcWAGjfaLJWiZqx8TRmN2qUOtpX9EwVxqS7ZHgZ++7qFJqw@mail.gmail.com
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In response to Re: Default timezone changes in 9.1  (Gavin Flower <GavinFlower@archidevsys.co.nz>)
Responses Re: Default timezone changes in 9.1
Re: Default timezone changes in 9.1
List pgsql-general
Sorry about the double post, I thought the list disallowed attachments so I sent it again with a pastebin link instead of an attachment.

This change does not affect the storage at all. If it did, pre-9.1 things would have been a mess. Rather, this allows the system to determine the timezone for localized use at runtime.

Post 9.1, the system determines this via initdb data directory initialization and automatically sets it within postgresql.conf.

In other words, the default now is *not* GMT but rather the system detected timezone at initdb runtime. Removing that statically set configuration option, in this case, *then* assumes GMT.

In other words, it may be 2 AM NZST, but would you really want to walk around and have all of your clocks read 1 PM (GMT)? :)

T.J.

On Sat, Dec 15, 2012 at 10:35 PM, Gavin Flower <GavinFlower@archidevsys.co.nz> wrote:
On 16/12/12 16:07, Terence Ferraro wrote:
We recently began upgrading our clients' servers from 9.0 -> 9.2. After a few deployments and a little digging we noticed that 9.0 -> 9.1 broke the use of no timezone set within postgresql.conf. That is, not setting the option was now defaulting to GMT instead of the system timezone. Unfortunately, this put quite a damper on our "one configuration file to rule them all" setup across servers located throughout various time zones.

I obtained the commit ca4af308c32d03db5fbacb54d6e583ceb904f268 from the git repository and have reversed it against 9.2. Though it didn't apply as smoothly as initially hoped; applying a few of the failed hunks manually allowed me to successfully compile 9.2.1 with these changes reversed.

After some (light) testing, the previous functionality of the system choosing the timezone at runtime seems to be functional again.

I found this functionality invaluable and figured I'd get the patch (http://pastebin.com/5AyaX2RF) posted in case anyone else ever needs this functionality back. It works against 9.2.1; no guarantees on future releases of course and YMMV.

T.J.

I simply do not understand why you would _NOT_ want to store date/times as GMT!

Storing as GMT, allows the times to be easily converted into whatever time zone you are in, also allows for times to be correctly ordered irrespective of time zone.

If I make a phone call from Auckland to New York at 2am NZST on Friday, then my colleague is talking to me at the same time - even though it is still Thursday for them!


Cheers,
Gavin


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