Correction: The phrase "Adding and deleting patch daily" should read "adding
and deleting paths daily".  Oops.

-----Original Message-----
From: John Clogg
Sent: Wednesday, February 12, 2003 10:48 AM
To: [log in to unmask]
Subject: Re: Skipper for Image and V-Plus


Michael,
I most certainly agree that absolute rules (never do this, always do that)
are seldom appropriate.  Fred White addressed the question of sorted chains
quite well in his paper "The Three Bears of Image", which I assume can be
found at the Adager web site.  The upshot of his message is that sorted
chains can be a resource hog if misused, but are useful if applied
appropriately.  (As I recall, he summed up the idea of using features
appropriately during his presentation of the paper at an HP3000 IUG
conference by saying "Don't take suppositories orally!")

Adding lots of entries to a sorted chain can be inefficient, if the entries
are added out of sequence.  For a database where PUTs are relatively
infrequent, and retrieval can be enhanced by having sorted chains, by all
means use them, especially if you can sort the entries before adding them to
the database!  I don't believe adding and deleting patch daily would be a
good idea.  Rebuilding all the chains would be a huge amount of work, and
would probably take more time than you would save by doing your updates
without the paths.

I am not familiar with Skipper.

-----Original Message-----
From: Michael Anderson [mailto:[log in to unmask]]
Sent: Wednesday, February 12, 2003 10:26 AM
To: [log in to unmask]
Subject: Skipper for Image and V-Plus


Hello to all,

Quick question;

I am in the process of designing an Image database, for quick day-time
inquiry, batch updates run at night. Because of this kind of database
usage, and the fact that it is mainly static historical data, and fast
retrieval is the number one requirement. I have used lots of paths,
including sorted paths. So called experts tell me all the time, not to
used too many paths, and never sorted paths. I disagree with
unconditional rules,  Like Never! Why is it that Image has sorted paths?
Like: Lets design in a feature, and tell everyone to avoid it at all
cost, doh. I understand the overhead, but that's only during
DBPUT,DBDELETE, right? Just looking at and old 1984 article that made
mention of Skipper. Has anyone ever used Skipper, a COBOL interface for
Image (on-the-fly chain sorts). I am curious about it, what it is, or
was, anyone know of this?

Would it be a wiser use of resources if I remove all paths before the
nightly batch updates, and re-add the paths when the batch updates are
complete? And of course I am referring to using ADAGER!





--
Michael Anderson
Spring Independent School District
16717 Ella Boulevard
Houston, Texas 77090-4299
office: 281.586.1105
fax: 281.586.1187
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