RE: RPG native to SQL

["Richard Jackson" <richardjackson@xxxxxxxxxxxxxxxxxx>]

Native IO has a different view of the tables than SQL IO.

It is possible to replace each read with a SELECT and each CHAIN/READE loop
with an OPEN CURSOR and FETCH loop.  You can use an IBM SQL language
extension to fetch and update records using relative record numbers (I think
...)  But SQL has a lot more overhead per statement and most single
statements (those not using a cursor) perform a full open and close on the
file.  Programs using a large variety of SQL statements will probably occupy
several times more virtual storage.  Please note that the ODBC driver
programs used by the ERP products easily use 30 megabytes of "warm" virtual
storage and sometimes use 100 megabytes.

You should rearchitect applications to take advantage of the strengths of
SQL (set selection and update) and to avoid the known issues and "badness of
fit".  In particular, the high cost per statement suggests that you should
execute several times fewer statements or buy hardware to offset the delta
and careful tuning or more memory will probably be required.


Richard Jackson
mailto:richardjackson@richardjackson.net
http://www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325

-----Original Message-----
From: owner-midrange-l@midrange.com
[mailto:owner-midrange-l@midrange.com]On Behalf Of Raikov, Lo
Sent: Tuesday, August 29, 2000 10:16 PM
To: 'MIDRANGE-L@midrange.com'
Subject: RPG native to SQL


Does anybody have experience converting native RPG to SQL RPG? Are there any
known methodologies? Tools? Consultancies?

Lo
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