Re: How to store data on an external drive

Hi Martin,

Thanks for reply.  However, your answer confuses me.

>your tables are probably not using the new default tablespace
>SET default_tablespace = new_tablespace_name
>any new tables will be placed into new default tablespace by inserting TABLESPACE clause

This is what I did:

I created tablespace on my home machine by using  CREATE TABLESPACE
psqldata LOCATION '/media/disk/psqldata'; The mounted folder
'/media/disk/psqldata' is on my external drive. Yes, it works fine on my
home machine when I use SET default_tablespace = psqldata.

The problem came when I went to work on my office machine with the same
external drive. I tried to create a tablespace by using the same clause,
CREATE TABLESPACE psqldata LOCATION '/media/disk/psqldata'; But, I got
an error message saying that I can create this table space because the
folder is not empty.  The PostgreSQL manual dose say "The location must
be an existing, empty directory" as in
http://www.postgresql.org/docs/8.3/static/manage-ag-tablespaces.html.
There is already stuff in that folder after I created the tablespace on
my home machine.

So, I did not even create a tablespace for that folder on my office
machine yet. I don't see how set SET default_tablespace =
new_tablespace_name can solve this problem.  Maybe, there was a
misunderstanding between us in your last e-mail.

 > Can you put the WHOLE database on the external drive?

This is my question to you guys.

I have not succeeded putting whole database on my external drive yet
with PostgreSQL. Yet, it seems to be easy to do the same with MySQL by
editing my.cnf file.  Thanks.

Best,
Jia

Martin Gainty wrote:
> your tables are probably not using the new default tablespace
>
> SET default_tablespace = new_tablespace_name
> any new tables will be placed into new default tablespace by inserting TABLESPACE clause
>
> can you put the WHOLE database on the external drive?
> Martin Gainty
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>
> > Date: Mon, 7 Sep 2009 20:20:52 -0400
> > From: chen.1002@gmail.com
> > To: pgsql-general@postgresql.org
> > Subject: [GENERAL] How to store data on an external drive
> >
> > Hi there,
> >
> > As a beginner of PostgreSQL, I installed PostgreSQL 8.3.7 on Ubuntu
> 9.04
> > by using sudo apt-get install.
> >
> > Now, I want to store PostgreSQL data on an external drive because I
> work
> > both on my office machine and on my home machine a lot. This way, I can
> > always bring my external drive to either location and work on data
> > stored on the drive.
> >
> > I tried to use tablespaces as in
> > http://www.postgresql.org/docs/8.3/static/manage-ag-tablespaces.html.
> > But, it does not seem to work because once I create a tablespace
> located
> > at one folder in the external drive for one machine, I can not create a
> > tablespace located at the same folder on the other machine since the
> > folder is not empty any more.
> >
> > Then, on my home machine, I copied everything in
> > /var/lib/postgresql/8.3/main to a folder on my external drive (say
> > folder /media/disk/psqldata) and edited postgresql.conf to comment out
> > line data_directory = '/var/lib/postgresql/8.3/main' and add
> > data_directory = '/media/disk/psqldata'. I am hoping that once I edit
> > postgresql.conf on my office machine the same way, it would work. But,
> > my guess is that this won't work.
> >
> > Please let me know whether this is right way to do it. Please let me
> > know your way of doing it too. Thanks.
> >
> > Best,
> > Jia
> >
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