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Re: Re: Proposal: Store "timestamptz" of database creation on "pg_database"

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: Kevin Grittner <kgrittn(at)mail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Christopher Browne <cbbrowne(at)gmail(dot)com>, Hannu Krosing <hannu(at)2ndquadrant(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Andres Freund <andres(at)2ndquadrant(dot)com>, Dimitri Fontaine <dimitri(at)2ndquadrant(dot)fr>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Re: Proposal: Store "timestamptz" of database creation on "pg_database"
Date: 2013-01-03 22:11:28
Message-ID: 50E60210.9000002@dunslane.net (view raw or flat)
Thread:
Lists: pgsql-hackers
On 01/03/2013 04:51 PM, Kevin Grittner wrote:
> Robert Haas wrote:
>> Christopher Browne <cbbrowne(at)gmail(dot)com> wrote:
>>> these timestamps Should Not be captured or carried forward by
>>> pg_dump.
>>> If we put a creation time into pg_database or pg_class, then
>>> streaming replication will, as a "physical" replication
>>> mechanism, carry the timestamp forward into replicas
>>> And in contrast, I'd expect Andres Freund's logical replication
>>> infrastructure *NOT* to carry these dates over, but rather to
>>> establish fresh new creation dates on a replica. (And from a
>>> forensic perspective, that's a perfectly fine thing.)
>> I agree all around.
> +1
>
> My analogy would be to xmin in tuples. Anything that preserves that
> should preserve table creation timestamp. If the tuples' xmin
> values in the table receiving the data differ, the creation
> timestamp should, too.
>
> In my experience, this would have been valuable forensic
> information many times. Preserving xmin rather than aggressively
> freezing never has been or would have been useful to me.
>


I don't especially have a horse in the race, but ISTM that if you want 
the information you want it to be able to persist across dump/restore, 
at least optionally. If you can happily lose it when you're forced to 
recover using a logical dump then it's not that important to you.


cheers

andrew


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