Thread: Postgresql DB on a live cd

Postgresql DB on a live cd

From
Lucio
Date:
Hi,

I'am trying to create a demo cd (knoppix) with a jdbc application.

This application uses a static (read-only, no insert, modify or delete) 200MB
postgresql db, so can't put pgsql/data/base and pgsql/data/pg_xlog in ramdisk.

postmaster fails to start because can't open the files in these two dirs with
read and write access.

The question is : can postmaster start only with read access ?

Any alternative solutions ?

Thank in advance,
Lucio


Re: Postgresql DB on a live cd

From
"Marc G. Fournier"
Date:
On Wed, 19 Nov 2003, Lucio wrote:

> Hi,
>
> I'am trying to create a demo cd (knoppix) with a jdbc application.
>
> This application uses a static (read-only, no insert, modify or delete) 200MB
> postgresql db, so can't put pgsql/data/base and pgsql/data/pg_xlog in ramdisk.
>
> postmaster fails to start because can't open the files in these two dirs with
> read and write access.
>
> The question is : can postmaster start only with read access ?
>
> Any alternative solutions ?

Create a memory file system and mount that onto as the directory its
trying to use?


Re: Postgresql DB on a live cd

From
Mailer
Date:
> Create a memory file system and mount that onto as the directory its
> trying to use?

Hi Marc

This is what Knoppix already makes: during boot creates /var/lib/pgsql as a link
to a ramdisk (maybe do you mean something different with "memory fs" ?)

Just now with pg_resetxlog (thanks god there's the net) I have cleared the
pg_xlog dir: 112MB --> 16MB   and this is a good first result.

Still continue to experiment...

Thanks and regards

Lucio


Re: Postgresql DB on a live cd

From
Ron Mayer
Date:
Lucio wrote:
> Hi,
>
> I'am trying to create a demo cd (knoppix) with a jdbc application.
>
> This application uses a static (read-only, no insert, modify or delete) 200MB
> postgresql db, so can't put pgsql/data/base and pgsql/data/pg_xlog in ramdisk.

One thing I don't think I saw mentioned yet....
I think some large sorts and temporary tables also use  ..../base/[whatevernumber]/pgsql_tmp
so you probably want to make that a symlink to something on the ramdisk
as well.

Re: Postgresql DB on a live cd

From
Ron Mayer
Date:
Lucio wrote:
>
> This application uses a static (read-only, no insert, modify or delete) 200MB
> postgresql db, so can't put pgsql/data/base and pgsql/data/pg_xlog in ramdisk.

One thing I don't think I saw mentioned yet....I think certain queries
create temporary tables (or at least use some temporary space) so  ..../base/[whatevernumber]/pgsql_tmp
should be a symlink to something on the ramdisk as well.

(Kinda off-topic -- anecdotally it feels to me that some queries
go faster if I put /pgsql_tmp on a different device & disk controller.
If I verify this I'll post results to perform)
  Ron Mayer  rm_pg@cheapcomplexdevices.com

Re: Postgresql DB on a live cd

From
Date:
Alle 09:47, giovedì 20 novembre 2003, Ron Mayer ha scritto:

> One thing I don't think I saw mentioned yet....I think certain queries
> create temporary tables (or at least use some temporary space) so
>    ..../base/[whatevernumber]/pgsql_tmp
> should be a symlink to something on the ramdisk as well.
>
> (Kinda off-topic -- anecdotally it feels to me that some queries
> go faster if I put /pgsql_tmp on a different device & disk controller.
> If I verify this I'll post results to perform)
>
>    Ron Mayer
>    rm_pg@cheapcomplexdevices.com

Hi, ron

Sorry, yesterday I was out for working.

Ye, pgsql/data/base is in ramdisk.

I have got to launch my live cd. After resetting pg_xlog,
the pgsql dir is only 80MB (from 200MB).

The requirements to run the live cd are now to 256MB RAM (sigh!!).

Regards

Lucio


Re: Postgresql DB on a live cd

From
Lucio
Date:
> Create a memory file system and mount that onto as the directory its
> trying to use?

Hi Marc

This is what Knoppix already makes: during boot creates /var/lib/pgsql as a link
to a ramdisk (maybe do you mean something different with "memory fs" ?)

Just now with pg_resetxlog (thanks god there's the net) I have cleared the
pg_xlog dir: 112MB --> 16MB   and this is a good first result.

Still continue to experiment...

Thanks and regards

Lucio