Another Way to Sort a File
January 16, 2008 Ted Holt
I’ve been in the information business for almost 27 years, and sometimes it seems that I’ve spent half that time sorting data. Without question, putting data into proper sequence is a big part of our jobs. Card sorters are ancient history. Sort utilities (e.g., #GSORT and FMTDTA) still run, but hopefully not in new development. These days, logical files and SQL are the iSeries methods of choice for placing data into a certain order. Here’s another sorting method you may not be aware of.
The Reorganize Physical File (RGZPFM) command’s KEYFILE parameter provides a way to physically order records in the file. If you specify KEYFILE(*FILE), the data will be stored in key sequence. You may also specify the name of a logical file if you wish to store the data in the order of the logical file’s key field(s). The end result is that programs may read the file in arrival sequence, which is faster than reading by key.
While I’m on the subject, let me mention KEYFIELD(*RPLDLTRCD), which I did not know existed. Selecting this option tells the system to replace deleted records at the top of the file with active records from the end of the file. I wonder how many releases ago IBM snuck that one in on me?