Re: [HACKERS] 8.5 TODO: Add comments to output indicating version of pg_dump and of the database server

[Philip Warner]

shakahsha...@gmail.com wrote:
> -- PostgreSQL database dump
> --
> -- pg_dump version: 8.5devel
> --
> -- remote database version: 8.5devel (80500)
> --
>   


FWIW, and I havent read the entire thread, but pg_dump already *stores*
this information in a custom format. Try:

pg_dump -Fc blah
pg_restore -L ...

and you will get something like:

;
; Archive created at Sun Nov 29 12:34:24 2009
; dbname: blah
; TOC Entries: 202
; Compression: -1
; Dump Version: 1.10-0
; Format: CUSTOM
; Integer: 4 bytes
; Offset: 8 bytes
; Dumped from database version: 8.0.3
; Dumped by pg_dump version: 8.0.3
;

so, all that is needed is to add the relevant statements into the output
code.



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Re: [HACKERS] 8.5 TODO: Add comments to output indicating version of pg_dump and of the database server

[Chris Browne]

pete...@gmx.net (Peter Eisentraut) writes:
> On Fri, 2009-09-25 at 16:59 -0400, Tom Lane wrote:
>> "shakahsha...@gmail.com"  writes:
>> > From pg_dump/pg_restore section (9.2 of the Todo page on the
>> > PostgreSQL Wiki), is the following item
>> >   "Add comments to output indicating version of pg_dump and of the
>> > database server"
>> > simply asking for a change to the pg_dump header from:
>> 
>> I think so, but what's not clear is whether this is a good idea to do
>> in the default output.  It might only be appropriate in "verbose" mode,
>> so as not to introduce unnecessary diffs between logically identical
>> dumps.
>
> Well, a diff of the same database made by different (major) versions of
> pg_dump will already be different in most situations, so adding the
> pg_dump version number in it is essentially free from this perspective.
>
> What is the use case for adding the server version?
>
> I can imagine something like wanting to know exactly where the dump came
> from, but then host name and such would be better.  (And then you can
> infer the server version from that.)

I added this ToDo because we had a case where we were spelunking
through some old pg_dumps, and the provenance was sufficiently distant
that we couldn't readily infer what PostgreSQL version was involved.

If pg_dump reported something like:

-- pg_dump version: 8.5_devel
-- postgres server version: 8.4.17

then it would be trivial to ascertain the information.

Actually, I have no argument with your point; perhaps a whole "header
section" is the right answer:

-- pg_dump version: 8.5_devel
-- postgres server version: 8.4.17
-- dump began at: 2010-07-01 14:22:27 EDT
-- server name: wolfe
-- more, maybe?


>> Another issue is that it's not all that clear what to do or how to do it
>> for archive dumps --- do you then want both pg_dump and pg_restore to
>> tell you about themselves?
>
> I don't see a good reason for pg_restore to get involved.

Agreed.  This isn't needed for pg_restore to do anything better; it's
so that humans can do better "archaeology."
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Re: [HACKERS] 8.5 TODO: Add comments to output indicating version of pg_dump and of the database server

[David Fetter]

On Sat, Sep 26, 2009 at 11:02:55PM +0300, Peter Eisentraut wrote:
> On Fri, 2009-09-25 at 16:59 -0400, Tom Lane wrote:
> > "shakahsha...@gmail.com"  writes:
> > > From pg_dump/pg_restore section (9.2 of the Todo page on the
> > > PostgreSQL Wiki), is the following item "Add comments to output
> > > indicating version of pg_dump and of the database server" simply
> > > asking for a change to the pg_dump header from:
> > 
> > I think so, but what's not clear is whether this is a good idea to
> > do in the default output.  It might only be appropriate in
> > "verbose" mode, so as not to introduce unnecessary diffs between
> > logically identical dumps.
> 
> Well, a diff of the same database made by different (major) versions
> of pg_dump will already be different in most situations, so adding
> the pg_dump version number in it is essentially free from this
> perspective.
> 
> What is the use case for adding the server version?

There have been cases where pg_restore doesn't fix infelicities.  For
example, there was a time when it was a good idea to run adddepend
after the reload.  Knowing what server version the dump came from
could be handy for this kind of case.

> I can imagine something like wanting to know exactly where the dump
> came from, but then host name and such would be better.  (And then
> you can infer the server version from that.)

You can infer the server version until the next upgrade, at which
point the information is lost.

Cheers,
David.
-- 
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Skype: davidfetter  XMPP: david.fet...@gmail.com

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Re: [HACKERS] 8.5 TODO: Add comments to output indicating version of pg_dump and of the database server

[Peter Eisentraut]

On Fri, 2009-09-25 at 16:59 -0400, Tom Lane wrote:
> "shakahsha...@gmail.com"  writes:
> > From pg_dump/pg_restore section (9.2 of the Todo page on the
> > PostgreSQL Wiki), is the following item
> >   "Add comments to output indicating version of pg_dump and of the
> > database server"
> > simply asking for a change to the pg_dump header from:
> 
> I think so, but what's not clear is whether this is a good idea to do
> in the default output.  It might only be appropriate in "verbose" mode,
> so as not to introduce unnecessary diffs between logically identical
> dumps.

Well, a diff of the same database made by different (major) versions of
pg_dump will already be different in most situations, so adding the
pg_dump version number in it is essentially free from this perspective.

What is the use case for adding the server version?

I can imagine something like wanting to know exactly where the dump came
from, but then host name and such would be better.  (And then you can
infer the server version from that.)

> Another issue is that it's not all that clear what to do or how to do it
> for archive dumps --- do you then want both pg_dump and pg_restore to
> tell you about themselves?

I don't see a good reason for pg_restore to get involved.



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Re: [HACKERS] 8.5 TODO: Add comments to output indicating version of pg_dump and of the database server

[Tom Lane]

"shakahsha...@gmail.com"  writes:
> From pg_dump/pg_restore section (9.2 of the Todo page on the
> PostgreSQL Wiki), is the following item
>   "Add comments to output indicating version of pg_dump and of the
> database server"
> simply asking for a change to the pg_dump header from:

I think so, but what's not clear is whether this is a good idea to do
in the default output.  It might only be appropriate in "verbose" mode,
so as not to introduce unnecessary diffs between logically identical
dumps.  We long ago got rid of timestamps in the default output for
exactly that reason.

Another issue is that it's not all that clear what to do or how to do it
for archive dumps --- do you then want both pg_dump and pg_restore to
tell you about themselves?  If pg_restore adds anything, then this'd
also break the principle that pg_dump >foo should give identical output
to pg_dump -Fc | pg_restore >foo.  Which is something that I for one
put a great deal of stock in, for testing purposes.

regards, tom lane

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[HACKERS] 8.5 TODO: Add comments to output indicating version of pg_dump and of the database server

[shakahsha...@gmail.com]

>From pg_dump/pg_restore section (9.2 of the Todo page on the
PostgreSQL Wiki), is the following item
  "Add comments to output indicating version of pg_dump and of the
database server"

simply asking for a change to the pg_dump header from:

--
-- PostgreSQL database dump
--

to something like:

-- PostgreSQL database dump
--
-- pg_dump version: 8.5devel
--
-- remote database version: 8.5devel (80500)
--

?

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