Date: Wed, 22 Feb 2017 09:22:28 -0800
From: David Fetter <david@fetter.org>
To: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Cc: Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>,
	Robert Haas <robertmhaas@gmail.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: Replication vs. float timestamps is a disaster
Message-ID: <20170222172228.GA22565@fetter.org>
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On Mon, Feb 20, 2017 at 11:58:12AM +0100, Petr Jelinek wrote:
> On 20/02/17 08:03, Andres Freund wrote:
> > On 2017-02-19 10:49:29 -0500, Tom Lane wrote:
> >> Robert Haas <robertmhaas@gmail.com> writes:
> >>> On Sun, Feb 19, 2017 at 3:31 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >>>> Thoughts?  Should we double down on trying to make this work according
> >>>> to the "all integer timestamps" protocol specs, or cut our losses and
> >>>> change the specs?
> >>
> >>> I vote for doubling down.  It's bad enough that we have so many
> >>> internal details that depend on this setting; letting that cascade
> >>> into the wire protocol seems like it's just letting the chaos spread
> >>> farther and wider.
> >>
> >> How do you figure that it's not embedded in the wire protocol already?
> >> Not only the replicated data for a timestamp column, but also the
> >> client-visible binary I/O format, depend on this.  I think having some
> >> parts of the protocol use a different timestamp format than other parts
> >> is simply weird, and as this exercise has shown, it's bug-prone as all
> >> get out.
> > 
> > I don't think it's that closely tied together atm. Things like
> > pg_basebackup, pg_receivexlog etc should work, without having to match
> > timestamp storage.  Logical replication, unless your output plugin dumps
> > data in binary / "raw" output, also works just fine across the timestamp
> > divide.
> > 
> > It doesn't sound that hard to add a SystemToIntTimestamp() function,
> > given it only needs to do something if float timestamps are enabled?
> > 
> 
> It's definitely not hard, we already have
> IntegerTimestampToTimestampTz() which does the opposite conversion anyway.
> 
> That being said, I did wonder myself if we should just deprecate float
> timestamps as well.

+1 for deprecating them.  If we need a timestamp(tz) with a wider
range, we are getting options we didn't have before for implementing
it.

Best,
David.
-- 
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
Skype: davidfetter      XMPP: david(dot)fetter(at)gmail(dot)com

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