Trailing-Edge
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PDP-10 Archives
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BB-H580E-SB_1985
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isam.hlp
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ISAM.HLP
ISAM - Indexed Sequential File Maintainence Program
/B Mode
Build Indexed File from Sequential Access File
.R ISAM
*indexfil,isamdatafil=sequfil/B
This mode is assumed by default if no mode switch is supplied.
If the device name is not specified for any file, "DSK:" is assumed.
The default extensions are, respectively, ".IDX", ".IDA", and ".SEQ".
If the isam data file name is omitted, the name of the index file is
used. If both the index file name and the isam data file name are
omitted, the name of the input file is used for them.
Answers to questions:
MODE OF INPUT FILE: S(ixbit), A(scii), F(ixed) or V(ariable)
MODE OF (ISAM) DATA FILE: S(ixbit), A(scii), F(ixed) or V(ariable)
(may differ from input)
MAXIMUM RECORD SIZE: (size of largest record of input file in
bytes)
KEY DESCRIPTOR: sxm.n
where s = S indicates the key is signed
s = U indicates the key is unsigned
x = X indicates the key is alphanumeric
x = N indicates the key is numeric display
x = C indicates the key is COMPUTATIONAL
x = F indicates the key is COMP-1
(floating point)
x = P indicates the key is COMP-3
(packed decimal)
m = the number of the byte in the record
where the key begins
n = the size of the key in bytes or digits
RECORDS PER INPUT BLOCK: number of records per logical block of the
input file (0 if unblocked)
SIZE OF LARGEST INPUT BLOCK: number of characters per block (asked
only if input file is unblocked and on
magtape)
TOTAL RECORDS PER DATA BLOCK: (RECOMMENDED = ): number of records
per logical block of the ISAM data file,
recommended number optimized for disk
space
EMPTY RECORDS PER DATA BLOCK: number of records to initially leave
empty in each data block (to facilitate
later random insertions)
TOTAL ENTRIES PER INDEX BLOCK: (RECOMMENDED = ): number of index
entries to be contained in each logical
block of the index file, recommended
number optimized for disk space
EMPTY ENTRIES PER INDEX BLOCK: number of entries to initially leave
empty in each index block
PERCENTAGE OF DATA FILE TO LEAVE EMPTY: essentially, this specifies
the number of additional empty blocks to
be initially added to the file (in order
to speed up later growth)
PERCENTAGE OF INDEX FILE TO LEAVE EMPTY: similar to above
MAXIMUM NUMBER OF RECORDS FILE CAN BECOME: a number in excess of what
the file is ever likely to grow to
/M Mode
Maintain Existing Indexed File
.R ISAM
*outputindexfil,outputdatafil=inputindexfil/M
Default devices are all "DSK:". Default extensions are, respectively,
".IDX", ".IDA", and ".IDX". Default filenames are as with the /B
mode.
Answers to questions are the same as for /B, except that only the last
5 questions are asked, and the existing values for these parameters
are typed in parentheses. Any of these parameters may be left
unchanged by typing just carriage-return.
/P Mode
Pack Indexed File Back into a Sequential File
.R ISAM
*sequfil=indexfil/P
Default devices are "DSK:". Default extensions are ".SEQ" and ".IDX",
respectively. If the sequential output file name is omitted, the name
of the index file is used.
Answers to questions:
MODE OF OUTPUT FILE: S(ixbit), A(scii), F(ixed) or V(ariable)
RECORDS PER OUTPUT BLOCK: blocking factor of output file
/I Mode
Ignore errors while /Packing or /Maintaining
.R ISAM
*sequfil=indexfil/P/I
When used in conjunction with /P or /M, /I will cause fatal errors
(prefixed with ?) to become warnings (prefixed with %), thus ignoring
the error.
/C Mode
Check an ISAM File for Errors
.R ISAM
*indexfil/C
Default device is "DSK:". Default extension is ".IDX".
The ISAM file is /Checked for errors. No file output is produced and
all errors are logged on the terminal as warnings.
/R Mode
Rename the ISAM File
.R ISAM
*outputindexfil,outputdatafil=inputindexfil/R
Default devices , file names and extensions are as defined for /M
The input ISAM file is /Renamed to be as defined in the output file
specification(s).
/S Mode
Provide Statistics when Building an ISAM File
.R ISAM
*indexfil,isamdatafil=sequfil/B/S
Used in conjunction with the /B switch, statistics describing various
index and data blocking factors are displayed during the build
dialogue.
/ADV Mode
Set Sequential ASCII Advancing
.R ISAM
*sequfil/A[DV]:mode=indexfil/P
where mode = 6[8] - use COBOL-68 default (BEFORE)
7[4] - use COBOL-74 default (AFTER)
A[FTER] - AFTER ADVANCING 1 LINE
B[EFORE] - BEFORE ADVANCING 1 LINE
When not specified with the /ADV switch, ADVANCING will default to the
COBOL-68 mode (BEFORE ADVANCING 1 LINE)."[" and "]" denote optional
syntax.
Indirect commands:
.R ISAM
*@commandfile.ext
[END OF ISAM.HLP]