READE implementation difficulties. RE: When is %EOF not an %EOF

["Steve Richter" <srichter@xxxxxxxxxxxxx>]

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Hans Boldt
Sent: Monday, September 29, 2003 11:08 AM
To: rpg400-l@xxxxxxxxxxxx
Subject: Re: When is %EOF not an %EOF

>Regarding READE, it's always been a thorn in the side of RPG
>development. At least, that's been my observation over the past 22
>years. Back in the S/38 days, there were significant performance
>problems with sparse keys and logicals over multiple physicals (if
>memory serves), which is why the "get next key equal" request was
>added. But there were still significant semantics mismatches, which
>is why the Factor-1 blank form was added. When implementing SAA
>RPG/370 in the late 80's, READE was the trickiest to get right. It's
>simply too weird a hybrid between a sequential and an indexed operation.

By "sparse keys" you mean that the next record is most likely not the same
key?

Was the difficulty only with READE in a file opened for update?  Without the
need for the database engine to read and lock the next sequential record,
couldnt READE be implemented solely in the compiled program code?  Where the
READE compiled code reads the next sequential record in the access path,
compares the keylist keys and returns EOF if it does not compare equal?

-Steve