Re: Tablespaces - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Tablespaces
Date
Msg-id 200403031752.i23HqeB03122@candle.pha.pa.us
Whole thread Raw
In response to Re: Tablespaces  (Greg Stark <gsstark@mit.edu>)
Responses Re: Tablespaces
Re: Tablespaces
List pgsql-hackers
Greg Stark wrote:
> 
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> 
> > Greg Stark wrote:
> > > 
> > > > > I am expecting to hear some bleating about this from people whose
> > > > > preferred platforms don't support symlinks ;-).  However, if we don't
> > > 
> > > Well, one option would be to have the low level filesystem storage (md.c?)
> > > routines implement a kind of symlink themselves. Just a file with a special
> > > magic number followed by a path.
> 
> On further contemplation it doesn't seem like using symlinks really ought to
> be necessary. It should be possible to drive everything off the catalog tables
> while avoidin having the low level filesystem code know anything about them.
> 
> Instead of having the low level code fetch the pg_* records themselves, some
> piece of higher level code would do the query and call down to storage layer
> to inform it of the locations for everything. It would have to do this on
> database initialization and on any subsequent object creation.
> 
> Basically maintain an in-memory hash table of oid -> path, and call down to
> the low level code whenever that hash changes. (Or more likely oid->ts_id and
> a separate list of ts_id -> path.)

The advantage of symlinks is that an administrator could see how things
are laid out from the command line.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
359-1001+  If your life is a hard drive,     |  13 Roberts Road +  Christ can be your backup.        |  Newtown Square,
Pennsylvania19073
 


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