Re: Should I replace all CHAIN, SETLL, and READs to SQL

Yes, SQL allows access via RRN, but you do not want to use it. As
accessing via RRN forces a full table scan.

Unless you plan to add a unique key, I'd stick with RLA.

Furthermore, simply replacing RLA op-codes with the SQL equivalent is
usually a bad idea; since the program is still designed for record at a
time processing. RPG RLA is optimized for record at a time, SQL is not.
SQL is designed to process sets. May not be such a big deal in an
interactive program...but for a batch program you'll end up with horrible
performance.

HTH,
Charles


On Fri, Nov 2, 2012 at 11:06 AM, John Allen <jallen@xxxxxxxxxxx> wrote:

I have been thinking about changing all CHAINs SETLLs and
READs in our software to SQL



Our programs use these operations for various reasons such
as:

Simple SETLL to check if a value is valid

Reading records for loading subfiles

Chaining by RRN (used in subfile processing, the input file
does not have a unique key so RRN is stored in Subfile then
used for accessing the original record)

Reading and chaining to several files for processing
thousands of records and doing validations, calculations
etc.



My main concern would be:

How this would affect performance

Does SQL allow for accessing records by RRN.



Does anyone have any thoughts on why this is a good or bad
idea



Thanks



John



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