Re: RPG and BLOCK(*YES)

["James W. Kilgore" <qappdsn@xxxxxxxxxxxxx>]

> <<SNIP>>
>
> Here are my questions:
> When should you use BLOCK(*YES)?

We use it when we are processing the file IP without a key.

>
> Is there an overhead to blocking?  For example if I am only reading a
> couple of records, does it take overhead to load a huge chunk of data for a
> couple of records?

I think that this may depend upon the drives being used and your blocking
factor.  I think that some have larger buffer sizes than others.


>
> Should you use it when doing random chains all over the file?

NO


>
> Should you use it when doing a SETLL/READ but only reading a few records?
> If not, then when is the cut over from when to use it and not to use it?

If you have a reasonable assurance that the data is in key order -AND- the
blocking factor will retrieve the records that you DO want.  Although I never
depend on this, cache seems to work fine here.

>

I have no hard evidence to support any of the above.  It's just from years of
tweaking a program here and there and noticing any run time changes.