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Browse Prior Art Database

Large Virtual Storage Exploitation of Data Space for Sorting

IP.com Disclosure Number: IPCOM000111160D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Kirchhofer, R: AUTHOR [+2]

Abstract

This method utilizes large amounts of virtual storage to achieve an efficient and fast sorting procedure. Although we present these ideas in the context of the MVS/ESA* Data Space mechanism, our ideas can be extended to use any areas of virtual storage.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Large Virtual Storage Exploitation of Data Space for Sorting

      This method utilizes large amounts of virtual storage to
achieve an efficient and fast sorting procedure.  Although we present
these ideas in the context of the MVS/ESA* Data Space mechanism, our
ideas can be extended to use any areas of virtual storage.

      With an external sort, subsets of a large file are sorted and
sorted sequences of records called runs are written to secondary
storage.  When sorting completes, the runs of data written by the
sorting procedure are read back from secondary storage and merged.

Typically storage for the sorting procedure of an external sort is
broken down into three parts:

1.  Input I/O buffers

2.  Output I/O buffers

3.  Record Storage Area (RSA)

      Sorting proceeds by reading a portion of the input file into
the input I/O buffers and moving the data into RSA.  When RSA fills,
records within RSA are sorted and moved to output I/O buffers to be
written to secondary storage.  This process continues until all of
the input data is sorted.  At that point, the remaining contents of
RSA are flushed to the output I/O buffers and written to secondary
storage.

           +--------------+
              |              |
              |  I/O buffers |
              |    for input |
              |    file      |
              +--------------+
              |  I/O buffers |
              |    for work  |
              |    file      |
              +--------------+
              |              |
              |              |
              |  Record      |
              |  Storage     |
              |  Area        |
              |              |
              |              |
              +--------------+

      The size of a run created during the sorting process is equal
to the size of RSA or can b...