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Re: [GENERAL] pg_migrator not setting values of sequences?

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Zdenek Kotala <Zdenek(dot)Kotala(at)Sun(dot)COM>, Tilmann Singer <tils(at)tils(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [GENERAL] pg_migrator not setting values of sequences?
Date: 2009-07-16 04:28:47
Message-ID: 200907160428.n6G4SlO11897@momjian.us (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-hackers
Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > Tom Lane wrote:
> >> The most effective solution might be to revert the change in pg_migrator
> >> and instead have pg_dump interpret --binary-upgrade --schema-only to
> >> include the data for sequences.  It seems ugly as sin though :-(
> 
> > Uh, how is this going to behave in 8.5?  Do we still dump sequences, and
> > if so, aren't we heading down the road of dumping stuff only because a
> > previous release needed it?
> 
> In 8.5 we'll probably have it go over to treating sequences the same as
> other user tables.  What, do you think that'll be the only change
> required in pg_migrator's behavior between 8.4 and 8.5?  I think it'll
> more likely be down in the noise ...

I am just worried about jerking pg_dump around as pg_migrator's needs
change.

> > Can we run a query that just shifts columns around in the sequence heap
> > files we migrated?
> 
> Nope.  That's not exposed at the SQL level, even if we allowed ALTER
> TABLE on sequences (which I sure hope we don't).

Ah, I see what you mean:

	test=> create sequence xx;
	seCREATE SEQUENCE
	test=> select * from xx;
	 sequence_name | last_value | start_value | increment_by |     
	max_value      | min_value | cache_value | log_cnt | is_cycled |
	is_called
	---------------+------------+-------------+--------------+---------------------+-----------+-------------+---------+-----------+-----------
	
	 xx            |          1 |           1 |            1 |
	9223372036854775807 |         1 |           1 |       1 | f         | f
	(1 row)
	
	test=> update xx set last_value = 3;
	ERROR:  cannot change sequence "xx"

-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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