Defining Functions › Device Functions › Standard Features—Processing Techniques

Standard Features—Processing Techniques

• Single Page Subfile (SFL) load up—Programs that use SFLs only load the SFL on a demand basis. Normally, this means only when the Rollup key or F8 is pressed. This makes their performance more efficient. However, the device function types that need to read all of a restricted number of records (namely the EDTTRN and DSPTRN functions) reads more than a page of records at a time if appropriate.
• Concurrency checking and record locking—Programs that update the database do not generally hold a lock on the database while the changes to the database are being entered and validated; that is, between reading an existing record and updating it. Instead, they include processing at the point of update to check that records were not altered by other users since the record was first accessed by the updating program. This approach prevents locking out any concurrent users or batch processes who or which may also need to update the file.
• Overflow handling—CA 2E generated report functions include exception handling to cope with page overflow. You can specify whether headings are reprinted or not.