Unlike CM KSAM files, KSAM XL 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 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 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.
Both types of KSAM files allow the reuse of index entry space for deleted entries, but only KSAM XL allows 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 files. Instead, KSAMUTIL functions have been integrated into the following CI commands:
The FCOPY utility provides a method of migrating CM KSAM files to KSAM XL. KSAM XL 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.
