SUBJECT:         APAR  NUMBER: PQ59219
 
REFERENCE:  AREA:     TPFDF CENTRAL DATABASE ROUTINES
            SEGMENT:  UWAP13     - RELEASE:  TPFDF (Assembler)
 
 
Pre-requisite APARs are (TPF only) :
FOR SEGMENT UWAP13     (Assembler) - REL TPFDF
 PQ32210  PQ48551  PQ60572  
To be applied in the order listed for each segment.
 
ABSTRACT OF PROBLEM
___________________
The  DBRED LAST command specified without keys may inefficiently
read each LREC in order to reach the last LREC.
 
COMMENTS ON PROBLEM
___________________
When a DBRED LAST command without keys is specified, and  it  is
not the first command following a DBOPN, processing will proceed
to  step through the subfile and traverse every LREC in order to
get to the last LREC. In most cases, however, the backward chain
field in the prime block is set up to point to the last LREC  in
the  chain.    It  is more efficient to directly access the last
LREC using the backward chain field.
 
SOLUTION
________
In UWAP, determine if it is possible to use the  backward  chain
field  in  order  to access the last LREC directly. If it can be
used, then access the last record in the chain directly.  If  it
is  not  possible,  then continue to read each LREC and traverse
the chain in order to find the last LREC.
 
DEPENDENCIES
____________
 
Related Segments Affected By This APAR.
_______________________________________
 
Segments to be assembled or compiled:
 
Segments to be link edited:
 
Load Modules to be loaded:
 
Migration Considerations
========================
      None
 
-- END APAR PQ59219
 
 
 


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