Thread: BLOBs

BLOBs

From
Dustin Sallings
Date:
    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?

    Is anyone working on BLOBs?

    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.  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.

    TIA.

--
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pub  1024/3CAE01D5 1994/11/03 Dustin Sallings <dustin@spy.net>
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L_______________________ I hope the answer won't upset her. ____________


Re: [GENERAL] BLOBs

From
Peter T Mount
Date:
[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