SQL to Oracle Linked Server Openquery retrieves single row

If you used the string like this "'MSDASQL','DRIVER={SQL Server};SERVER=INDIANBANK;UID=ags;PWD=mypass', 'Select * From ATM_PROGNOSIS.IR_ATMMON_AGS'" you got DSN-less connection so tests of DSN are useless.

I recommend you to take this driver
Oracle Data Provider for .NET
It's much more friendly with Oracle.

Here is
the example for ODP.NET
where tuning is described.

And here is the full docs for ODP.NET

Hope this helps :)

See my comments below.

P.S. For Microsoft driver the parameters are shown hereMicrosoft OLE DB Provider for ODBC

My solution of the same problem was

Set Numeric Settings parameter to US numeric in Oracle ODBC driver settings.

Quote from ODBC help, problematic stuff is underlined) Numeric Settings - Allows you to choose which numeric settings will be used to determine the decimal and group separator characters when receiving and returning numeric data that is bound as strings. This option allows you to choose Oracle NLS settings (the default setting), Microsoft default regional settings (to provide a way to mirror the Oracle OLE DB driver’s behavior for greater interoperability), or US numeric settings (which are necessary when using MS Access or DAO (Database Access Objects) in non-US environments).