I have to read a large volume of data into a GSAM file in a program that employs check pointing. I want to access this data in a random fashion in the subsequent steps.
Can a GSAM file have a key and can we access it with a GU call using the key?
The problem why I am not trying out VSAM is that I donot want to repeat the copy process in case I get an abend.
An IMS program can retrieve records and add records to the end of the GSAM database, but the program cannot delete or replace records in the database.
You use separate calls to access GSAM databases. (Additional checkpoint and restart considerations are involved in using GSAM.)
Your program must use symbolic CHKP and XRST calls if it uses GSAM. Basic CHKP calls cannot checkpoint GSAM databases.
When an IMS program uses a GSAM data set, the program treats it like a sequential nonhierarchic database. The MVS access methods that GSAM can use are BSAM on direct access, unit record, and tape devices; and VSAM on direct-access storage. VSAM data sets must be nonkeyed, non indexed, entry-sequenced data sets (ESDS) and must reside on DASD. VSAM does not support temporary, SYSIN, SYSOUT, and unit-record files.
Because GSAM is a sequential nonhierarchic database, it has no segments, no keys, and no parentage.