Re: How to move a tablespace?

Robert Treat <xzilla(at)users(dot)sourceforge(dot)net> writes:
> On Friday 22 June 2007 14:14, Chris Hoover wrote:
>> How do you correctly move a tablespace?
>>
>> I am thinking this would be the process:
>> 1. Cleanly shutdown Postgres
>> 2. Move tablespace directory and all contents to new location
>> 3. Create a symlink from the new location back to the old location
>> 4. Restart Postgres

> On a side note, this is one reason to make tablespaces on clean mount points,
> so that you can swap the disk systems out underneath, but maintain the same
> mountpoint, and not let the db care about the difference.

But you'd still have to shut down the postmaster.

The fine manual sayeth

: The directory $PGDATA/pg_tblspc contains symbolic links that point to
: each of the non-built-in tablespaces defined in the cluster. Although
: not recommended, it is possible to adjust the tablespace layout by hand
: by redefining these links. Two warnings: do not do so while the server
: is running; and after you restart the server, update the pg_tablespace
: catalog to show the new locations. (If you do not, pg_dump will continue
: to show the old tablespace locations.)

and elsewhere

: Each user-defined tablespace has a symbolic link inside the
: PGDATA/pg_tblspc directory, which points to the physical tablespace
: directory (as specified in its CREATE TABLESPACE command). The symbolic
: link is named after the tablespace's OID. Inside the physical tablespace
: directory there is a subdirectory for each database that has elements in
: the tablespace, named after the database's OID. Tables within that
: directory follow the filenode naming scheme. The pg_default tablespace
: is not accessed through pg_tblspc, but corresponds to
: PGDATA/base. Similarly, the pg_global tablespace is not accessed through
: pg_tblspc, but corresponds to PGDATA/global.

regards, tom lane