Using Range Modification Routines

The modify range routines perform similarly to their predecessors, the E@DBLOCKGE and E@DBLOCKNXT calls. The modify range routines are better choices to use in many cases than E@DBLOCKGE and E@DBLOCKNXT, because the modify range routines have some added performance advantages.

E@DBLOCKBEGRNG and E@DBLOCKMIDRNG are used for initial processing of data and E@DBLOCKSUBRNG and E@DBLOCKMIDSUB are used for repositioning within the initial cursor. To continue processing the cursor, once repositioning is done, the E@DBLOCKNXTRNG is used.

The E@DBLOCKMIDRNG and E@DBLOCKMIDSUB, with their ability to reposition within a cursor, are useful for:

• Screen scrolling (page up and page down) within online programs

• Recovery of batch jobs

• Continuation after a transaction end in online programs where the end of the main transaction does a close of all open cursors

For more information on the differences between the find and modify range calls and the performance advantages you gain through the use of range calls, see Using Range Find Routines.