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ramu_mohan21 · Posted: Tue Nov 09, 2004 5:13 am Post subject: Type of Datasets in IMS Database

Hi Board,
I'm sorry for asking one fundamental question. Please can any one help me in getting the answer.

In our installation we are using some of IMS Database datasets are VSAM and some are seems to be Flat Files.

Can we use the Flat files as a IMS Database.

And also
I saw the DBD Source in my installation.

For VSAM IMS Database Dataset I found
ACCESS=(INDEX,VSAM)
-> I couldn't able to browse the this kind of IMS Database dataset using ISPF 3.4 Option. But I can do it using FileAid

For another kind of IMS Database Dataset(As I mentioned above as Flat Files)
ACCESS=(HIDAM,OSAM)
-> I am able to browse this kind of IMS Database dataset using ISPF 3.4 Option.

Now I am assuming that if IMS Database Dataset is defined as "ACCESS=(HIDAM,OSAM)" then we can browse using ISPF 3.4 option. I hope my analysis is right.

Any one can confirm my analysis.
_________________
Best Regards,
----------------
Rammohan Pabba
Software Engineer

Bithead · Posted: Tue Nov 09, 2004 9:15 am Post subject:

You will be able to browse OSAM (overflow sequential access method) files because they are sequential. They are defined in two parts - a root area and an overflow area. IMS will attempt to place data into the root area but, if it cannot, it will place it in the overflow area.

The data that you see in the file will be scattered across the file and will probably be out of sequence so it will be very difficult to follow. Also, browsing IMS databases may interfere with IMS operations so it is not recommended.

The other kind of flat file is a GSAM (generalized sequential access method). This type of file is more like the sequential file that you are used to.

ramu_mohan21 · Posted: Wed Nov 10, 2004 8:06 am Post subject:

Hi Bithead,
Thank you very much for giving me the clear explanation.
_________________
Best Regards,
----------------
Rammohan Pabba
Software Engineer