> I actually meant I thought we were going to have a pg_class column
> called relversion that held the currently active version for that
> relation.
> 
> Yes, the file name will be pg_class_oid.version_id.
> 
> Is that OK?

We recently discussed pure *unique-id* file names...

Vadim
 

Tue, 27 Jun 2000 12:42:35 -0700
"Mikheev, Vadim" <vmikheev@SECTORBASE.COM>
RE: Big 7.1 open items
[ Charset ISO-8859-1 unsupported, converting... ]
> > I actually meant I thought we were going to have a pg_class column
> > called relversion that held the currently active version for that
> > relation.
> > 
> > Yes, the file name will be pg_class_oid.version_id.
> > 
> > Is that OK?
> 
> We recently discussed pure *unique-id* file names...
> 

Well, that would allow us to mix database files in the same directory,
if we wanted to do that.  My opinion it is better to keep databases in
separate directories in each tablespace for clarity and performance
reasons.


-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

Tue, 27 Jun 2000 15:52:40 -0400 (EDT)
Bruce Momjian <pgman@candle.pha.pa.us>
Re: Big 7.1 open items
Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Well, that would allow us to mix database files in the same directory,
> if we wanted to do that.  My opinion it is better to keep databases in
> separate directories in each tablespace for clarity and performance
> reasons.

One reason not to do that is that we'd still have to special-case
the system-wide relations.  If it's just tablespace and OID in the
path, then the system-wide rels look just the same as any other rel
as far as the low-level stuff is concerned.  That would be nice.

My feeling about the "clarity and performance" issue is that if a
dbadmin wants to keep track of database contents separately, he can
put different databases' tables into different tablespaces to start
with.  If he puts several tables into one tablespace, he's saying
he doesn't care about distinguishing their space usage.  There's
no reason for us to force an additional level of directory lookup
to be done whether the admin wants it or not.

			regards, tom lane

Tue, 27 Jun 2000 17:19:31 -0400
Tom Lane <tgl@sss.pgh.pa.us>
Re: Big 7.1 open items 
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Well, that would allow us to mix database files in the same directory,
> > if we wanted to do that.  My opinion it is better to keep databases in
> > separate directories in each tablespace for clarity and performance
> > reasons.
> 
> One reason not to do that is that we'd still have to special-case
> the system-wide relations.  If it's just tablespace and OID in the
> path, then the system-wide rels look just the same as any other rel
> as far as the low-level stuff is concerned.  That would be nice.

Yes, good point about pg_shadow.  They don't have databases.  How do we
get multiple pg_class tables in the same directory?  Is the
pg_class.relversion file a number like 1,2,3,4, or does it come out of
some global counter like oid.  If so, we could put them in the same
directory.

Should we be concerned about performance when 10-20 database are sitting
in the same directory?  I am thinking about open() and other calls that
scan the directory.  Certainly shorter file names will help.

> 
> My feeling about the "clarity and performance" issue is that if a
> dbadmin wants to keep track of database contents separately, he can
> put different databases' tables into different tablespaces to start
> with.  If he puts several tables into one tablespace, he's saying
> he doesn't care about distinguishing their space usage.  There's
> no reason for us to force an additional level of directory lookup
> to be done whether the admin wants it or not.

OK.

-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

Tue, 27 Jun 2000 17:23:49 -0400 (EDT)
Bruce Momjian <pgman@candle.pha.pa.us>
Re: Big 7.1 open items
Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Yes, good point about pg_shadow.  They don't have databases.  How do we
> get multiple pg_class tables in the same directory?  Is the
> pg_class.relversion file a number like 1,2,3,4, or does it come out of
> some global counter like oid.  If so, we could put them in the same
> directory.

I think we could get away with insisting that each database store its
pg_class and friends in a separate tablespace (physically distinct
directory) from any other database.  That gets around the OID conflict.

It's still an open question whether OID+version is better than
unique-ID for naming files that belong to different versions of the
same relation.  I can see arguments on both sides.

			regards, tom lane

Tue, 27 Jun 2000 17:30:17 -0400
Tom Lane <tgl@sss.pgh.pa.us>
Re: Big 7.1 open items 
Tom Lane wrote:

> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Yes, good point about pg_shadow.  They don't have databases.  How do we
> > get multiple pg_class tables in the same directory?  Is the
> > pg_class.relversion file a number like 1,2,3,4, or does it come out of
> > some global counter like oid.  If so, we could put them in the same
> > directory.
>
> I think we could get away with insisting that each database store its
> pg_class and friends in a separate tablespace (physically distinct
> directory) from any other database.  That gets around the OID conflict.
>
> It's still an open question whether OID+version is better than
> unique-ID for naming files that belong to different versions of the
> same relation.  I can see arguments on both sides.
>

I don't stick to unique-ID. My main point has always been the
transactional control of file allocation change.
However *VERSION(_ID)* may be misleading because it couldn't
mean the version of pg_class tuples.

Regards.

Hiroshi Inoue
Inoue@tpf.co.jp



Wed, 28 Jun 2000 08:16:27 +0900
Hiroshi Inoue <Inoue@tpf.co.jp>
Re: Big 7.1 open items
Bruce Momjian writes:

> How do we get multiple pg_class tables in the same directory?

pg_class.DBOID


-- 
Peter Eisentraut                  Sernanders vï¿½g 10:115
peter_e@gmx.net                   75262 Uppsala
http://yi.org/peter-e/            Sweden



Wed, 28 Jun 2000 20:37:44 +0200 (CEST)
Peter Eisentraut <peter_e@gmx.net>
Re: Big 7.1 open items