RE: What about Blobs? -- MIDRANGE-L

I guess it has more to do with my own laziness than anything else.  The
"pointer to the folder containing" method may be more efficient but I am
thinking more about implementation and operational details more than
anything.  Not sure if PTTFC ("pointer to the folder containing") method is
harder to deploy to Linux vs. Windows vs. iSeries.  If the data is in a blob
in a column in a table, I know exactly where to get it and store it and, I
only have one record to monitor.  Imagine a successful write to the table
but the data fails to update or write to the IFS.  Yeah, more commitment
control and editing will take care of that but I told you, I'm lazy.  One
record, one read, one update, one delete.  It *seems* simpler.

Somewhere on this list is probably a chart comparing the 'write to the table
with a blob column' method to the 'write to the table AND the folder'
method.  Such a thing would be interesting to see on a new i5.  Are we
talking minutes, seconds, milliseconds?

Thanks for your perspective. It IS worth a look.


Pete Helgren
Value Added Software, Inc
801.581.1154 x202

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Nathan M. Andelin
Sent: Thursday, January 27, 2005 4:35 PM
To: 'Midrange Systems Technical Discussion'
Subject: RE: What about Blobs?

Pete,

Blob fields may be a bit more "cross platform" in the sense that utilities
exist to export iSeries tables containing blob fields to MS SQL Server (for
example), without needing to convert the "/" in IFS file references to "\"
for Windows.

On the other hand, you might also want to consider runtime efficiencies.  If
you're planning on using blob fields for storing documents, images, and
other binary files, which users may need to access from a browser, wouldn't
you have to convert the Blob to a "temporary" directory, pass the URL to the
browser, then cleanup temporary stream files later?

If the files are stored in a directory to begin with, all you need to do is
pass the URL to the browser.  Correct me if mistaken, but Blobs can't be
stored on "optical" media.  IFS files can be simply copied to an optical
drive and "file paths" changed to reflect the move, so you're not using hard
drives to store files that might otherwise be archived to  optical media
(which is more economical).

Is your primary goal to streamline the migration of applications and data to
other platforms, or to offer operational efficiencies to end-users?

Nathan.


-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Pete Helgren
Sent: Thursday, January 27, 2005 3:28 PM
To: 'Midrange Systems Technical Discussion'
Subject: What about Blobs?


(Wasn't that a movie title?)

Anyway, as a follow up to my success with the VARLEN data type (varchar),
can the same be done with BLOB's?  That is, can a BLOB be defined in DDS ? I
saw plenty of Blob posts, but no example about how it is done in DDS.  Use
SQL to Alter Table maybe?  Or, is a BLOB a whole different beast and needs
to be created only through SQL?

The alternative, as mentioned in many posts, is to point to a location the
IFS and store that location in a table column.  Since this is a Java app,
the blob type seems more "cross platform", at least allowing me to write and
test code while hanging in the sky at 30,000 for hours on end..

Open to other suggestions on how best to manage it. 

Pete Helgren
Value Added Software, Inc
801.581.1154 x202



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