Synchronize filenames in table with filesystem

On Tue, Dec 1, 2009 at 9:19 AM, Ludwig Kniprath <ludwig@kni-online.de> wrote:

Hi List,
not another question on how to store files (db or filesystem), i decided to use the filesystem.

I'm now searching for a trigger, that deletes the physical file when deleting a database-record containing the filename in one of its fields. Is there a sample somewhere how this could be done? I'm runnig PG 8.4 on a windows machine.

Perhaps when you delete your record, you can use a before delete
trigger to insert this path to a "Files_To_Delete" table. Then using
Cron, you can query this table to get the list of file you want to
delete.

On the other hand, if you really want to delete each file with a
trigger, you are probably better off using Large Objects (lo):
http://www.postgresql.org/docs/8.4/interactive/lo.html

And in the off chance that you one day use the truncate command you
can periodically schedule the vacuumlo command:
http://www.postgresql.org/docs/8.4/interactive/vacuumlo.html

--
Regards,
Richard Broersma Jr.

Visit the Los Angeles PostgreSQL Users Group (LAPUG)
http://pugs.postgresql.org/lapug

On Dec 1, 2009, at 9:19 AM, Ludwig Kniprath wrote:

Hi List,
not another question on how to store files (db or filesystem), i decided to use the filesystem.

I'm now searching for a trigger, that deletes the physical file when deleting a database-record containing the filename in one of its fields. Is there a sample somewhere how this could be done? I'm runnig PG 8.4 on a windows machine.

I've done that by having the trigger put the name of the file to be deleted in a "to be deleted" table. Then an external process polls that table and deletes any file it finds in there (using listen/notify if you need that to happen immediately, but just polling works fine if it's just garbage collection).

That has the advantage of not deleting files until the transaction commits too.

Cheers,
Steve

-----Original Message-----
From: pgsql-general-owner@postgresql.org
[mailto:pgsql-general-owner@postgresql.org] On Behalf Of Steve Atkins
Sent: Tuesday, December 01, 2009 9:44 AM
To: pgsql-general General
Subject: Re: [GENERAL] Synchronize filenames in table with filesystem

On Dec 1, 2009, at 9:19 AM, Ludwig Kniprath wrote:

Hi List,
not another question on how to store files (db or

filesystem), i decided to use the filesystem.

I'm now searching for a trigger, that deletes the physical

file when deleting a database-record containing the filename
in one of its fields. Is there a sample somewhere how this
could be done? I'm runnig PG 8.4 on a windows machine.

I've done that by having the trigger put the name of the file
to be deleted in a "to be deleted" table. Then an external
process polls that table and deletes any file it finds in
there (using listen/notify if you need that to happen
immediately, but just polling works fine if it's just garbage
collection).

That has the advantage of not deleting files until the
transaction commits too.

Cheers,
Steve

--
Sent via pgsql-general mailing list
(pgsql-general@postgresql.org) To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

I'm with Ludwig..

Better to have the database perform it's primary function, and stay away
from os chores.

You can also use LISTEN/NOTIFY.