Normally SQL simply ignores a logical, it simply uses it to find the
physical. Normally you always use the physical and it is up to SQL to
decide which index it will use.

The exception to this is if the logical has select/omit. The SQL will honor
it but it used to drop into the old Sequel query engine. They may have
fixed that but normally you would not want to do that. You let SQL decide
whats the best way.

Logicals are not something that SQL understands. Logicals are a file I/O
concept.

I use array's to read multiple records equal to the Sfl Page size + 1.but I
would consider this an advanced subject. SQL provides what I think are
superior facilities for doing screen I/O but you have to think differently.
.

On Thu, Sep 3, 2015 at 1:14 PM, Booth Martin <booth@xxxxxxxxxxxx> wrote:

I am fairly new with SQL so please excuse what are most likely very simple
questions.

I am looking to understand the pros and cons with SQL.
On large files with data that will be used in various applications and in
various sort-by schemes, are logical files a help?
If so, does one reference the physical file and then SQL finds the best
logical, or does it help to specify a specific logical file?
What is the right way to collect a set of records equal to SFLPAGE?

So far, I believe my biggest problem is that I haven't yet figured out how
to ask the right questions.


--
Booth Martin
www.martinvt.com
(802)461-5349

If the world comes to an end, I want to be in Cincinnati. Everything comes
there ten years later. -- Mark Twain
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