We have a DB2 database in AS400. Added a linked server, all went well, however occasionally the table is locked, even when we doing some select queries. Thinking about table hint in SQL Server, does the linked server query (e.g. select * from ...) support table hint?
Doubtful, but I don't know for sure.
Are you using openquery() , or 4 part names?
A query using 4 part names like so:
select * from LNKSVRNAME.IBMINAME.MYSCHEMA.MYTABLE where somecolumn = '00335';
Pulls back all the rows from MYTABLE and does the WHERE filtering on MS SQL Server.
In contrast, using openquery() like so:
select * from openquery(LNKSVRNAME, 'select * from MYSCHEMA.MYTABLE where somecolumn = ''00335''');
Sends the query to the IBM i, and only the matching rows from MYTABLE are pulled back into MS SQL Server.
If the table is being locked exclusively, there's not much you can do. However, if you're running into row locks. You may want to look at the following DB2 for IBM i clauses
FOR READ ONLYSKIP LOCKED DATA or USE CURRENTLY COMMITTED or WAIT FOR OUTCOMESo something like this:
select * from openquery(LNKSVRNAME, 'select * from MYSCHEMA.MYTABLE where somecolumn = ''00335'' FOR READ ONLY USE CURRENTLY COMMITTED');
Note If you are actually talking to an AS/400, FOR READ ONLY is all you'll have available. But if you're talking to a relatively recent IBM POWER System running a relatively recent version of IBM i, then the concurrent-access-resolution clauses I've shown should be available.