[EMAIL PROTECTED] wrote:
I wonder - Why is it not possible to add records to the beginning of a data set? Wouldn't it be possible for a sufficiently clever program to place the inserted records into a newly allocated area on disk, and then modify the VTOC to point to that new area first and the old first area next? It might require rewriting a bunch of control blocks, and probably wouldn't work for some kinds of data sets (FBS comes to mind), but isn't it theoretically possible?
I'm speculating, but sequential files (QSAM, BSAM) were designed to be as device independent as possible. While your proposal would work a few times for a DASD file, it would not work on tape. Furthermore, while there may be a business case for inserting records into a file, the specific case of doing so only at the beginning is pretty rare, and wouldn't justify the expense of implementation.
Gerhard Postpischil Bradford, VT ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
