On 7/18/07, Schuh, Richard <[EMAIL PROTECTED]> wrote:

Without BOB, the primary input would never present a record to the fanin
if you let it default to the normal order of primary then secondary. The
full array would not be created; instead, the pipe would either end
without creating the array or it might stall.

:-)  I round that to one point for sure.
The book says that end-of-file is not propagated on the primary input
of gate so fanin will not see end-of-file on its primary until gate
terminates. That's the point where fanin will switch to the secondary
input. So even though we know records will either be on the primary or
secondary, the reversed order is needed to prevent a stalled pipeline.

Rob

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