-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Hi all,
now that we have the tablespace support don't you think that
each tablespace needs his own costs instead of a system wide
one ?

I searched in the archives and on the TODO list without success.

Regards
Gaetano Mendola


-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (MingW32)
Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org

iD8DBQFBIz2i7UpzwH2SGd4RAvLqAJ9fKt/1wy8sKySEIptubwz+CR85CACg/q3x
IOPx9xKYld8WJJaDaydQtgE=
=8w+B
-----END PGP SIGNATURE-----


Wed, 18 Aug 2004 13:31:49 +0200
Gaetano Mendola <mendola@bigfoot.com>
Tablespace and cpu costs
On Wed, 18 Aug 2004, Gaetano Mendola wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Hi all,
> now that we have the tablespace support don't you think that
> each tablespace needs his own costs instead of a system wide
> one ?
>
> I searched in the archives and on the TODO list without success.

Yep. I've looked at this but didn't think it necessary for the first stage
of implementation.

I definately plan to do it for 8.1

Gavin

Wed, 18 Aug 2004 22:23:21 +1000 (EST)
Gavin Sherry <swm@linuxworld.com.au>
Re: Tablespace and cpu costs
Gavin Sherry wrote:

> On Wed, 18 Aug 2004, Gaetano Mendola wrote:
>>-----BEGIN PGP SIGNED MESSAGE-----
>>Hash: SHA1
>>
>>Hi all,
>>now that we have the tablespace support don't you think that
>>each tablespace needs his own costs instead of a system wide
>>one ?
>>
>>I searched in the archives and on the TODO list without success.
> 
> 
> Yep. I've looked at this but didn't think it necessary for the first stage
> of implementation.
> 
> I definately plan to do it for 8.1

Do you have an Idea on how you want implement this ( usage side ) ?



Regards
Gaetano Mendola



Wed, 18 Aug 2004 16:51:31 +0200
Gaetano Mendola <mendola@bigfoot.com>
Re: Tablespace and cpu costs
On Wed, 18 Aug 2004, Gaetano Mendola wrote:

> Gavin Sherry wrote:
>
> > On Wed, 18 Aug 2004, Gaetano Mendola wrote:
> >>-----BEGIN PGP SIGNED MESSAGE-----
> >>Hash: SHA1
> >>
> >>Hi all,
> >>now that we have the tablespace support don't you think that
> >>each tablespace needs his own costs instead of a system wide
> >>one ?
> >>
> >>I searched in the archives and on the TODO list without success.
> >
> >
> > Yep. I've looked at this but didn't think it necessary for the first stage
> > of implementation.
> >
> > I definately plan to do it for 8.1
>
> Do you have an Idea on how you want implement this ( usage side ) ?
>

Well, as far as I can tell there are two ways we could do it without
reinventing the wheel -- but both are ugly.

The first is to add a parameter to CREATE TABLESPACE and ALTER TABLESPACE
called RANDOMPAGECOST (or something like that) which allows users to set
the random page cost for a given tablespace. I'm undecided as to whether
they should be able to set the sequential scan cost. That seems
reasonable too at first look.

The second option is to have a pg_tablespace.conf file which defines
tablespace specific settings in some way or another.

Either way, the data will be feed into the planner so that the costing
routines will be able to use them.

Anyone else got some thoughts on how we could do this in a cleaner manner?

Gavin

Thu, 19 Aug 2004 09:40:28 +1000 (EST)
Gavin Sherry <swm@linuxworld.com.au>
Re: Tablespace and cpu costs
> The first is to add a parameter to CREATE TABLESPACE and ALTER TABLESPACE
> called RANDOMPAGECOST (or something like that) which allows users to set
> the random page cost for a given tablespace. I'm undecided as to whether
> they should be able to set the sequential scan cost. That seems
> reasonable too at first look.
> 
> The second option is to have a pg_tablespace.conf file which defines
> tablespace specific settings in some way or another.
> 
> Either way, the data will be feed into the planner so that the costing
> routines will be able to use them.
> 
> Anyone else got some thoughts on how we could do this in a cleaner manner?

Yes, exactly like we have ALTER USER SET blah=foo; and ALTER DATABASE 
SET blah = foo;

Chris


Thu, 19 Aug 2004 09:40:23 +0800
Christopher Kings-Lynne <chriskl@familyhealth.com.au>
Re: Tablespace and cpu costs
Gavin Sherry wrote:

> On Wed, 18 Aug 2004, Gaetano Mendola wrote:
> 
> 
>>Gavin Sherry wrote:
>>
>>
>>>On Wed, 18 Aug 2004, Gaetano Mendola wrote:
>>>
>>>>-----BEGIN PGP SIGNED MESSAGE-----
>>>>Hash: SHA1
>>>>
>>>>Hi all,
>>>>now that we have the tablespace support don't you think that
>>>>each tablespace needs his own costs instead of a system wide
>>>>one ?
>>>>
>>>>I searched in the archives and on the TODO list without success.
>>>
>>>
>>>Yep. I've looked at this but didn't think it necessary for the first stage
>>>of implementation.
>>>
>>>I definately plan to do it for 8.1
>>
>>Do you have an Idea on how you want implement this ( usage side ) ?
>>
> 
> 
> Well, as far as I can tell there are two ways we could do it without
> reinventing the wheel -- but both are ugly.
> 
> The first is to add a parameter to CREATE TABLESPACE and ALTER TABLESPACE
> called RANDOMPAGECOST (or something like that) which allows users to set
> the random page cost for a given tablespace. I'm undecided as to whether
> they should be able to set the sequential scan cost. That seems
> reasonable too at first look.
> 
> The second option is to have a pg_tablespace.conf file which defines
> tablespace specific settings in some way or another.
> 
> Either way, the data will be feed into the planner so that the costing
> routines will be able to use them.

That is the goal.

> Anyone else got some thoughts on how we could do this in a cleaner manner?

I think we need both, I think could be also usefull add a STORE option:

ALTER TABLESPACE RANDOMPAGECOST 0.001 STORE

if the STORE is present then the pg_tablespace.conf is updated

this could be argued with the fact that we do not have SET cpu_costs STORE bu this
doesn't mean that we can not have it in the future :-)

I think is also usefull insert it in the dump "as comment" before the tablespace
creation, this in order to don't loose these setting.


Regards
Gaetano Mendola
















Thu, 19 Aug 2004 12:30:42 +0200
Gaetano Mendola <mendola@bigfoot.com>
Re: Tablespace and cpu costs