FastSort Manual

Introduction to FastSort

FastSort Manual—429834-003

1-9

Scratch Files

FastSort sorts files smaller than 100 kilobytes in memory. For larger input files,

FastSort uses up to 32 scratch files to temporarily store groups of records called runs.

You can create a scratch file before you run FastSort, or you can have SORTPROG

create one for you. If you manually create a scratch file, SORTPROG leaves the file

intact after the sort or merge run. If SORTPROG creates the scratch file, it is a

temporary file and SORTPROG automatically purges it after the sort completes.

Once an initial scratch file exists, FastSort creates additional scratch files as needed. If

the initial scratch file becomes full, FastSort automatically creates overflow scratch files

until either the sort completes or there are 32 total scratch files. A sort operation

requires scratch space equal to all output records from the SORTPROG process plus

6 bytes per record for overhead. For more information about scratch files, see

Section 9, Optimizing Sort Performance.

Output Files

FastSort can send output to most types of disk files, except EDIT files or

NonStop SQL/MP objects. FastSort can send output to a tape file, but it cannot write

records to blocked tape files. After a sort or merge run, you can use FUP to load a

blocked tape file. For instructions about using FUP, see the File Utility Program (FUP)

Reference Manual. You can also load your output into an EDIT file using the EDIT GET

command. For instructions on how to use the GET command, see Appendix C, Using

Supported File Types.

You can have FastSort compute the size of the output file and then create it, or you

can specify an existing output file. For more information about output files, see

Appendix C, Using Supported File Types.

Using DEFINEs With FastSort

You can use DEFINEs to configure most aspects of a sort or merge operation.

FastSort recognizes class SPOOL and class SORT or SUBSORT DEFINEs. DEFINEs

are optional.

Class SPOOL DEFINE

FastSort allows a class SPOOL DEFINE for the list file (that is, the TACL RUN

command OUT parameter). For example, the following implicit TACL RUN command

specifies a SPOOL DEFINE named =out_file for the FastSort list file. The TACL

ADD DEFINE command first creates the SPOOL DEFINE and sets the LOC attribute.

ADD DEFINE =out_file, CLASS SPOOL, LOC \ny.$s.#sort

...

SORT / OUT =out_file /

...

For more information about class SPOOL DEFINEs, see Guardian User’s Guide.