Re: Record blocking optimization

Secondary files are optional.  In general it works like this, it reads all 
records from the primary file, and then reads all records from Each 
secondary file in the order they are listed.  Now, there are things you 
can do with matching records and stuff.  But I've only used that once in a 
proof of concept, and it seemed interesting.  Wait, I did screw up a 
matching records program on a S/36 back around 1984.

When you compile with a primary file, that file will get a nice 
RNF7086-RPG handles blocking for the file. message.

Rob Berendt
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Tony Carolla <carolla@xxxxxxxxx> 
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03/15/2005 03:50 PM
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Re: Record blocking optimization






Thanks for the info.  That 'sequential only' language had me worried. 

<snip>
> That said, on first listen, this sounds like it might lend itself to the
> old RPG cycle, which still works in RPG-IV, if the idea is to optimize.
> It's hard to beat the cycle, though I'm sure buffering optimization
> would get close.  Using primary and secondary, the compiler sets up the
> optimum block size.
</snip>

My curiosity is piqued.  My mindset has been on avoiding the cycle,
and just optimizing this thing as best as I can (read blocking, using
all DSs for input/output/updates, etc).

Now this is a little humbling, but I am a late comer to the game of
RPG (I have used IV only, and was taught to avoid the cycle at all
costs), and I have never written a pgm using the cycle AND primary AND
secondary input files.  I know that if you specify a file as input
primary, every record will be read from the file, and the calc specs
will be repeated for each record, but I am not sure how the secondary
file plays into this.  Is a record automatically read from the
secondary file also?


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