The main difference is where the data is stored.

With a BLOB the data is considered stored in the row (record).  Actually
it's probably some space object behind the scenes (there's a 16 Mb size
limit). You can think of a BLOB as a very big data field.

With a DATALINK the data is in the IFS or some remote system and it's
referenced by URL instead.  Hence why it's called a link.  You can think of
the field as containing the path to your stream file.

A windows app could use ODBC to read your image db, then use the URL
w/access token to open the image file from the IFS.


----- Original Message ----- 
From: "Dan Bale" <dbale@xxxxxxxxxxxxx>
To: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx>
Sent: Friday, October 08, 2004 9:56 AM
Subject: DATALINK (was: How can I store an externally generated PDF in afile
or outq)

> > Alternately there is another database field type called a
> > DATALINK which contains the URL (path) of the PDF file.
> > If setup with "database permissions", the system will
> > secure the PDF file in the IFS and require an "access
> > token" read from the database file in order to reference
> > the PDF file.
> Whoa, I think I need to know more about this DATALINK.  We have a need in
> the near future to reference photos, drawings, signatures that will be
> stored in the IFS and link them to a particular record in the native
> database.  Or should I say, the native file record will have links to the
> IFS objects.  Without fully recognizing all of the capabilities, the only
> function I could see using this for would be to automatically pop up a
> photo/drawing/signature in Windows when a user hits a function key on a
> green-screen app (F9=Show mug shot).
> However, looking through the archives, I have to wonder how stable this
> In, Richard
> Theis of IBM shows what appear to be several complex steps to set up and
> then adds "Sometimes, it works !"  He provides a reference that I have yet
> to look at, but if it is typical of most IBM manuals, it won't give any
> to" advice.
> I guess I'm still unclear about the difference between a BLOB and a
> DATALINK.  Anyone feel like taking a stab?
> tia,
> db
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