Ben wrote: > Hi, > > How can I know the T24 is sequential , random or mix? > I guess T24 is mix. It has sequential and random both. > Yes. You cannot really tell about T24 unless you are looking at the code. I suspect that as with many other programs it does a lot of SSELECT when it really only needs SELECT. Obviously online (people based) inquiries will be random access, but batch jobs should do their best to provide sequential access if possible. This is complicated/prevented in some cases by the fact that a batch job may be reading through one file sequentially, but reading and writing to many others in random fashion. In that case, you will be limited by the random IO pattern rather than the sequential. > If I execute the select in Jbase, it is sequential or random IO? > In jbase or T24, there are many api such as SELECT, READ, WRITE, > READNEXT etc. How can I know they are sequential or random? > Basica rule of thumb is:
jBC SELECT/SELECT/LIST - provides a sequential recordset in hash order of the file; SSELECT/SORT - Access sequentially while SELECTIng, but then sorts the keys and traversing a sorted list will generate random access; You also need your files to be well sized ( a little over sized is good). Jim --~--~---------~--~----~------------~-------~--~----~ Please read the posting guidelines at: http://groups.google.com/group/jBASE/web/Posting%20Guidelines IMPORTANT: Type T24: at the start of the subject line for questions specific to Globus/T24 To post, send email to [email protected] To unsubscribe, send email to [email protected] For more options, visit this group at http://groups.google.com/group/jBASE?hl=en -~----------~----~----~----~------~----~------~--~---
