SQL Server synonym used in two ways, local table and Oracle table via ODBC, fails on ODBC

Question

I am implementing a Web Site at our institution that was written for another institution that was all SQL Server.The Web Site has included as a feature the use of synonyms which have a dual use. Normally they point to a different machine, different database (PeopleSoft)
via linked server, but if the linked server connection fails they can be switched to point to tables on the local instance by running a stored procedure that redefines the synonyms. This is a failover feature meant to keep the site up by resorting to
possibly out of date data if need be.
This means that any SQL Select statement that uses one of these synonyms is unaware of whether the data returned comes from the local instance or from another remote instance. There is no logic to check whether the linked server is functioning or not.
The local instance is a custom SQL Server database at both institutions. The remote instance is one of two PeopleSoft instances at both shops; however, while the original website was written to work with the remote instance being SQL Server,
our shop uses Oracle for PeopleSoft. This means that our linked servers are further complicated by an ODBC connection that the original site did not need.
The problem I have is that the SQL statements in the stored procedures that came with the Web Site do not work when a synonym is used that points to the remote PeopleSoft instance. The same statements also fail in SSMS.  I get this error when I run
this statement (select * from PS_ZZ_BUD_JOB_VW):
Error: The OLE DB provider "OraOLEDB.Oracle" for linked server "CSUPG" does not contain the table
     ""dbo"."PS_ZZ_BUD_JOB_VW"". The table either does not exist or the current user does not have  permissions on that table.
I can successfully query the PeopleSoft database using openquery, but unless I can get the synonyms to work as they were intended to, I'll have to rewrite all the stored procedures that use them to: 1) check if the linked servers are up, then 2) execute
one of two versions of each SQL statement depending on the result of that check.

Answer 1

Will the four-part notation work when the synonym is pointing to the local SQL Server table ?
You should not use four-part notation when you reference your synonym. The four-part query that I suggested is only one you would to determine to define our synonym correctly when the view is on the Oracle server.
In the case of synonym PS_ZZ_BUD_JOB_VW, it can point to either an Oracle view of the same name, or to a local SQL Server table named PS_HR_JOB.
Then the table is local the synonuym definition should be
CREATE SYNONYM PS_ZZ_BUD_JOB_VW FOR dbo.PS_HR_JOB
Erland Sommarskog, SQL Server MVP, [email protected]