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Unlike CM KSAM files, KSAM XL and KSAM64 data records and
indexes are combined in a single file. The file limit of KSAM XL
files is substantially larger than CM KSAM files. The physical size
of the KSAM file is the same as the MPE/iX native mode flat file.
KSAM XL and KSAM64 files allow only fixed-length records.
CM KSAM files allow fixed-length or variable-length records. When
the data is copied from CM KSAM variable-length records to KSAM
XL or KSAM64 fixed-length records, shorter records are padded with
a fill character to the defined fixed-length record size. The fill
character is specified during the file creation. The default fill
character for an ASCII file is a blank. The default fill character
for a binary file is a binary zero.
The three types of KSAM files allow the reuse of index entry
space for deleted entries, but only KSAM XL and KSAM64 allow the
reuse of deleted record space. If chronological order of the records
is not necessary, deleted record space can be reused.
KSAMUTIL, the utility used to create, rename, and purge CM KSAM files,
does not support KSAM XL and KSAM64 files. Instead, KSAMUTIL functions
have been integrated into the following CI commands:
BUILD PURGE RENAME LISTFILE
The FCOPY utility provides a method of migrating CM KSAM files
to KSAM XL and KSAM64. KSAM XL and KSAM64 files, however, cannot
use the NOKSAM option in file copying.
Transaction management guarantees consistency and recoverability from system
crashes. System logging provides this recoverability. System logging is
attached after the first FCLOSE of the file. This occurs automatically
with the BUILD command. Files built with HPFOPEN or
FOPEN intrinsics are attached after the first FCLOSE
intrinsic call or with the DOMAIN=CREATE option of the
HPFOPEN intrinsic.
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