At 3:55 PM -0500 on 06/27/2010, Paul Gilmartin wrote about Re: Delete
all members of a PDS that is allocated:
On Sun, 27 Jun 2010 09:30:10 -0500, Joel C. Ewing wrote:
the CBT PDS utility). I wouldn't call deleting all individual members
via ISPF LM services a viable production approach except for a PDS with
a small number of members, or perhaps for a one time exercise. Going
that route starts off requiring an order of magnitude more processing
resources than a "reset" for even a small PDS and gets exponentially
worse as the number of members increases.
Not exponentially. Quadratically, if I understand the technique.
-- gil
If I remember correctly, the index blocks at the start of PDS are
filled with the directory entries and when you delete one member, all
of the subsequent entries shift forward (and shift from block to
block). Thus when you delete in alpha order (as opposed to reverse
alpha order), you remove the first member entry and all the others
shift to fill the gap. Assuming that the same number of members fill
each block (due to being the same length) then the number of write
operations is computed by this method:
T = Total number of Members
M = The number of members per block
For I = 1 to T
Compute the Sum of the Ceiling of I/M (Ceiling meaning I/M rounded up
to the next integer).
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