MERGE, Output File Qualifiers
*Conan The Librarian (sorry for the slow response - running on an old VAX)
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VMS Help MERGE, Output File Qualifiers *Conan The Librarian (sorry for the slow response - running on an old VAX) |
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Must be specified immediately after the output file specification
in the SORT or MERGE command line.
1 - /ALLOCATION
Specifies the number of blocks to be preallocated for the output
file. Used for optimization when you know that the output file
allocation will differ substantially from the total input
file allocation (because you are reformatting data or omitting
records).
Format
output-file-spec/ALLOCATION=n
1.1 - Qualifier Value
n
Specifies the number of blocks to be allocated. A value of 1 to
4,294,967,295 is allowed.
1.2 - Full Description
Sort/Merge preallocates space for the output file based on total
input file allocation, thereby avoiding the overhead of extending
the file every time another few blocks are written to it.
However, if you know that the output file allocation will differ
substantially from the total input file allocation (because you
are reformatting data or omitting records), you can specify the
number of blocks to be preallocated for the output file.
The /ALLOCATION qualifier is required if the /CONTIGUOUS
qualifier is used.
1.3 - Example
$ SORT/KEY=(POS:1,SIZ:80) STATS.DAT -
_$ SUMMARY.LIS/ALLOCATION=1000/CONTIGUOUS
This SORT command allocates 1000 contiguous blocks for the
output file SUMMARY.LIS.
2 - /BUCKET_SIZE
Specifies the OpenVMS RMS bucket size (the number of 512-byte
blocks per bucket) for the output file. Used with relative and
indexed-sequential output disk files for optimization.
Format
output-file-spec/BUCKET_SIZE=n
2.1 - Qualifier Value
n
Specifies the bucket size. A value of 1 to 32 is allowed.
2.2 - Full Description
Use the /BUCKET_SIZE qualifier with relative and indexed-
sequential output disk files to specify OpenVMS RMS bucket size
(the number of 512-byte blocks per bucket). If the output file
organization is the same as for the input files, the default
value is the same as the first input file bucket size. If output
file organization is different, the default value is 1. The
maximum number of blocks per bucket is 32.
2.3 - Example
$ SORT/KEY=(POS:1,SIZ:80) STATS1.DAT,STATS2.DAT -
_$ SUMMARY.LIS/BUCKET_SIZE=16/RELATIVE
This SORT command results in the output file SUMMARY.LIS that
has a bucket size of 16 with relative organization.
3 - /CONTIGUOUS
Requests that the output file be stored in contiguous disk
blocks, thereby decreasing access time. Note that you must also
specify the /ALLOCATION qualifier because if the preallocated
space is too small, OpenVMS RMS may be unable to extend the file
contiguously.
Format
output-file-spec/CONTIGUOUS
3.1 - Full Description
By default, Sort/Merge does not allocate contiguous disk blocks
for the output file. You can request, however, that the output
file be stored in contiguous disk blocks by specifying the
/CONTIGUOUS qualifier, thereby decreasing access time. If you use
the /CONTIGUOUS qualifier, you must also specify the /ALLOCATION
qualifier because if the preallocated space is too small, OpenVMS
RMS may be unable to extend the file contiguously.
3.2 - Example
$ SORT/KEY=(POS:1,SIZ:80) STATS.DAT -
_$ SUMMARY.LIS/ALLOCATION=1000/CONTIGUOUS
This SORT command allocates 1,000 contiguous blocks for the
output file SUMMARY.LIS.
4 - /FORMAT
Specifies the output file record format if it differs from the
input file format.
Format
output-file-spec/FORMAT=(type:n ...)
4.1 - Qualifier Values
BLOCK_SIZE:n
Specifies the output file's block size, in bytes, if you have
directed the file to magnetic tape. You can also accept the
default. If the input file is a tape file, the block size of
the output file defaults to that of the input file. Otherwise,
the output file block size defaults to the size used when the
tape was mounted.
Acceptable values for block size n range from 20 to 65,532. To
ensure correct data interchange with other Compaq systems,
however, specify a block size of not more than 512 bytes. For
compatibility with systems that are not made by Compaq, the
block size should not exceed 2,048 bytes.
CONTROLLED:n
Specifies variable with fixed-length control (VFC) records in the
output file.
n
Optionally indicates the maximum record size (in bytes) of the
output records. The maximum record size allowed depends on the
file organization.
Sequential files 32,767
Relative files 16,383
Indexed-sequential files 16,362
These totals include control bytes. If you do not specify the
maximum record size, the default is a length large enough to hold
the longest output record.
FIXED:n
Specifies fixed-length records in the output file.
SIZE:n
Specifies the size, in bytes, of the fixed portion of VFC
(CONTROLLED) records, up to a maximum of 255 bytes. If you do
not specify SIZE, the default is the size of the fixed portion of
the first input file. If you specify this size as 0, OpenVMS RMS
defaults the value to 2 bytes.
VARIABLE:n
Specifies variable-length records in the output file.
4.2 - Full Description
If the sort operation is a record or tag sort, the default output
record format is the same as the first input file record format.
If the sort operation is an address or index sort, the default
output record format is fixed record format. If the input files
have different record formats, Sort provides an output record
size that is large enough to contain the largest record in the
input files.
When you specify the output record format, you can indicate
the maximum record size, in bytes, of the output records. You
can specify fixed-length records, variable-length records, or
variable with fixed-length control records.
4.3 - Example
$ SORT/KEY=(POS:1,SIZ:80) STATS.DAT SUMMARY.LIS/FORMAT=FIXED:80
The input file STATS.DAT consists of variable-length records
that are 80 bytes in length. The /FORMAT qualifier specifies
that the output file, SUMMARY.LIS, consists of fixed-length
records.
5 - /INDEXED_SEQUENTIAL
Defines the output file organization as indexed sequential. The
output file must exist and must be empty. Used with the /OVERLAY
qualifier.
Format
output-file-spec/INDEXED_SEQUENTIAL
5.1 - Full Description
If the organization of the output file is to be different
from that of the input files, then you must specify the
new organization. Use the /INDEXED_SEQUENTIAL qualifier to
define indexed-sequential organization for the output file.
Additionally, the output file must exist and must be empty, and
you must use the /OVERLAY qualifier.
5.2 - Example
$ CREATE/FDL=NEW.FDL AVERAGE.DAT
$ SORT/KEY=(POS:1,SIZ:80) DATA.DAT,STATS.DAT -
_$ AVERAGE.DAT/INDEXED_SEQUENTIAL/OVERLAY
The CREATE/FDL command creates the empty file AVERAGE.DAT. The
SORT command specifies that the output file have an indexed-
sequential organization and be written to the empty file
AVERAGE.DAT.
6 - /OVERLAY
Specifies an existing empty file that the output file is to be
overlaid, or written to. The /OVERLAY qualifier is required when
you use the /INDEXED_SEQUENTIAL qualifier.
Format
output-file-spec/OVERLAY
6.1 - Full Description
To specify that an empty file is to be overlaid with sorted
records, use the /OVERLAY qualifier.
If the input file organization is indexed-sequential, the output
file must already exist and must be empty. If the output file
is not empty, /OVERLAY does not write over the file. Instead, it
appends the result of the sort to the existing output file.
If the input file organization is sequential or relative, you can
create an empty file for the sorted records using an OpenVMS RMS
program and use the /OVERLAY qualifier to specify that the output
file is to be overlaid.
You can use the Create/FDL utility to create an empty data
file; use the /OVERLAY qualifier to specify that Sort is to
write output to that file. Any attributes that you specify when
creating the empty file then become attributes of the Sort output
file.
See the OpenVMS Record Management Services Reference Manual for
more information. You can also refer to this manual if you want
to use the Convert utility to produce an indexed-sequential file
on output.
6.2 - Example
$ CREATE/FDL=NEW.FDL AVERAGE.DAT
$ SORT/KEY=(POS:1,SIZ:80) STATS.DAT AVERAGE.DAT/OVERLAY
The FDL file NEW.FDL specifies special attributes for the
file AVERAGE.DAT. When Sort writes output to that file, the
resulting Sort output file has the attributes specified by the
FDL file.
7 - /RELATIVE
Defines the output file organization as relative.
Format
output-file-spec/RELATIVE
7.1 - Full Description
If the organization of the output file is to be different
from that of the input files, then you must specify the new
organization. If you do not specify file organization, the
default for record and tag sorts is the organization of the
first input file. You must use the /RELATIVE qualifier to specify
relative output file organization.
7.2 - Example
$ SORT/KEY=(POS:1,SIZ:80) STATS.DAT SUMMARY.LIS/RELATIVE
Because the input file STATS.DAT is not a relative file and
the output file, SUMMARY.LIS, will be, /RELATIVE qualifies the
output file specification.
8 - /SEQUENTIAL
Defines output file organization as sequential. This is the
default for address and index sorts. (The default for record
and tag sorts is the organization of the first input file.)
Format
output-file-spec/SEQUENTIAL
8.1 - Full Description
If the organization of the output file is to be different from
that of the input files, you must specify the new organization.
If you do not specify file organization, the default for record
and tag sorts is the organization of the first input file. If you
do not specify file organization, the default organization for
address and index sorts is sequential.
Use the /SEQUENTIAL qualifier when the default is not sequential
file organization and you want an output file with sequential
file format.
8.2 - Example
$ SORT/KEY=(POS:1,SIZ:80) STATS.DAT SUMMARY.LIS/SEQUENTIAL
Because the input file STATS.DAT is not a sequential file and
the output file SUMMARY.LIS will be, /SEQUENTIAL qualifies the
output file specification.
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