Edward Brown wrote:
I don't agree. Disk access is inherently slower than RAM access.
Therefore a process that makes efficient use of RAM will be faster than
an equivalent algorithm making efficient use of disk.
In your case, it's just a matter of scale:
50 million records at (lets say) 14 bytes per ID plus the multivalue
marker needed to build up the dynamic array.
15 * 50,000,000 = 750,000,000 bytes.
That's 732,422KB, 715MB
If your process is running on a modern server then this kind of op
becomes practical.
Assumptions:
- that the dynamic array isn't using Unicode. If it is then memory
reqirements double.
- That you select every record - normally (presumably) it would be just
a fraction?
In fact isn't all of this theoretical? Using the index select / readfwd
/ own tests method, there's no need to build workfiles or dynamic arrays
at all - simply do the tests as each record is retrieved with readfwd
and then create the report / do the processing all within the same loop?
Ed
The only real reason I can see for _really_ needing the extra data
structure or workfile is if you have post sorting, maybe on a calculated
value, say sorting on a totaled value. You need a pass through the data
first to get that value.
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