+   RMS records, index keys, and RFA access?    The Question is:     Dear Wizard,   L please could you tell me if accessing records in an RMS indexed file is more$  efficient by RFA or by primary key?   M Is the access by RFA adversely affected by bucket splits and record deletions 
  for example?    
 kind regards,     Matthew French  The Answer is :   G   Yes, RFA access is always more efficient than access by an index key.    F   Accessing a record by RFA allows RMS to go directly the bucket whereF   the record was originally created, and look for the correct ID usingE   a simple binary match, and normally a single cache lookup or I/O is 	   needed.    G   There are cases where RMS might perform the lookup and might not find F   the record itself, where RMS might find a RRV for it; a redirection.E   This case arises if the record was ever involved in a bucket split. F   RMS will then follow that RRV for an additional cache lookup (and anB   I/O, if neeed).  There will be no more than one RRV indirection.   G   Accessing a record by primary key involves at least one index lookup, D   and more commonly additional lookups as the index tree is commonlyF   two or three or more levels deep.   From the lowest-level index, RMSE   locates the bucket that actually currently holds the record and RMS B   will then sequentially scan that bucket looking for a key match,>   using the appropriate comparisons and decompression support.   C   Obviously RFA access is always more efficient, and can be roughly    three times more efficent.   D   Bucket splits, as referenced above, can cause a redirection shouldF   the have been resident in the upper portion of the split bucket.  IfF   subsequent bucket splits occur, the original RRV is updated to pointI   to the current residence for the record; there is only one indirection. G   As follows from this, bucket splits can be expensive operations owing 3   to the need to update all existing affected RRVs.    D   Do realize that RFA-based pointers require maintaining consistencyF   across the contents of the target file and a separate storage of RFA   information.   0  Answer written or last revised on  19-MAY-2004 