Browse Prior Art Database

Allocation of Buffers in External Sorting Operations

IP.com Disclosure Number: IPCOM000102845D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 35K

Publishing Venue

IBM

Related People

Conner, WM: AUTHOR

Abstract

This invention relates to a method for allocating buffers in the overlapping input and output phases in CPU-based external sorting operations. In this regard, the number of available buffers is a function of the merge order M, the merge order being the number of strings created in the initial run generation phase of the external sort.

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Allocation of Buffers in External Sorting Operations

      This invention relates to a method for allocating buffers in
the overlapping input and output phases in CPU-based external sorting
operations.  In this regard, the number of available buffers is a
function of the merge order M, the merge order being the number of
strings created in the initial run generation phase of the external
sort.

      The method comprises the steps of (a) ascertaining the total
internal storage for the external sort less the minimum storage
required for merging; (b) calculating the factor W = M*B*L/2, B being
the blocking factor and L being the record length; and (c)
determining the transfer buffer unit X available as the total storage
- W - minimum merge requirement.

      For any given number of buffers, the number assigned to
maximize throughput in overlapped input and output external sorting
operations is data dependent.  The numbers or ratio varies as to
whether the data is random or presequenced. I/O buffer allocation
tuned for a random data string would be out of tune for presequenced
data.  Sampling of the key value distribution for tuning the
allocation would require an additional data pass.  The method
provides a broad rather than narrow throughput bandpass solution.

      Disclosed anonymously.