SQL vs. READ Performance Opinions

["Brian Piotrowski" <bpiotrowski@xxxxxxxxxxxxxxx>]

Hi All,

 

I was having a discussion with a fellow RPG programmer on the merits of
using SQL vs. a READ command in RPG.  Can someone tell me about their
experiences with using SQL over an RPG read command in terms of
performance?

 

Let me give you an example - we have a physical file that contains over
100,000 records.  We have a program that searches from a "FROM" date and
reads to either the end of the file or the "TO" date, whichever comes
first.  The program that does the READ statement uses a logical file.
The SQL statement uses a BETWEEN parameter to only select those records
that match the indicated criteria.

 

>From what understand, there would be a disk I/O for every record it
needs to read between the FROM and TO dates.  However, with an SQL
SELECT statement, I would only encounter a single disk I/O.

 

Is this correct?  In the case of this above program, which is the most
efficient way of getting the data?

 

Thanks!

 

Brian.

 

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Brian Piotrowski

Specialist - I.T.

Simcoe Parts Service, Inc.

Ph: 705-435-7814 x343

Fx: 705-435-6746

bpiotrowski@xxxxxxxxxxxxxxx

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