RE: Implicit Access Path Sharing

["David Morris" <dmorris@xxxxxxxxxxxxx>]

Brad,

You are right that it makes no sense unless some other criteria is 
added.  The most likely criteria for me would be to specify that A 
is a unique key.  I would most likely do this when A is the primary key 
to a file and B is a commonly used attribute of the based on file.  This 
allows the commonly used attribute to be retrieved directly from the 
access path without requiring additional I/O.  For example I might set 
up a key of customer number and name and a unique key of customer 
number.  Once this is done, an SQL statement that joins to the customer 
file to select customer names can run significantly faster.

David Morris

>>> "Stone, Brad V (TC)" <bvstone@taylorcorp.com> 04/28/99 07:47AM >>>
Then the question is, if you already had LF1 with A & B as keys (and no
selects, etc), why would you create LF2 with A as a key?  That's redundant
to begin with and does you no good assuming there are no other criteria
needed by either logical.

Bradley V. Stone
Taylor Corporation - OASIS Programmer/Analyst   
bvstone@taylorcorp.com 



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