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List:       postgresql-general
Subject:    Re: [GENERAL] BLOBs
From:       Peter T Mount <peter () retep ! org ! uk>
Date:       1998-07-25 11:38:41
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[moved this to the hackers list]

On Thu, 23 Jul 1998, Dustin Sallings wrote:

> 
> 	Hey, I never saw a follow-up on any of the BLOB questions, so I thought
> I'd throw them in here again:
> 
> 	Is there a way to actually *delete* a BLOB?

the lo_unlink() function will delete the blob given it's oid.

> 	Is anyone working on BLOBs?

I'm working on the blob orphaning problem that exists for JDBC & ODBC.

> 	Last time I tried to use it, it seemed to store each BLOB in a file by
> itself (two files?) in the middle of my data directory, which seems like a very
> bad thing IMO.

The current scheme actually creates a table and index pair for each blob,
which is what you are seeing.

There was talk of having another storage manager which stores all of them
in a single file, but nothing happened with it.

>  I also couldn't find any documented way of removing them, and
> simply deleting the file(s) caused my vacuum to fail.  I'd really like to use
> BLOBs instead of nasty MIME encoding of large images, but I'd definitely need
> to be able to delete, and it'd be nice if I wouldn't fill up that one directory
> with them.  If nobody is working on BLOBs, it might be fun to find a way to
> implement another storage mechanism, possibly a single file (group of files) to
> store the BLOB, or a directory hierarchy.

Take a look at the ImageViewer example in the src/interfaces/jdbc/examples
directory. Ok, it's in java, but it does show how to store, retrieve and
delete images from a database.

-- 
Peter T Mount peter@retep.org.uk or petermount@earthling.net
Main Homepage: http://www.retep.org.uk
************ Someday I may rebuild this signature completely ;-) ************
Work Homepage: http://www.maidstone.gov.uk Work EMail: peter@maidstone.gov.uk

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