I am thinking of changing the read isolation level for our SQL Server libraries to Read Uncommitted. This means that it will not lock the database when reading, but may read dirty data. In our case the timing of our overnight run means that there should not be any dirty data at that time to be read. I have heard that this change is likely to provide a performance boost. Can anyone advise whether this is likely to provide any performance boost? I know it all depends on what we are doing. Also, is it likely to help with locking problems which we are also having at times? It seems to me like it would help since there would be no need to lock tables any more. We are using SQL Server on a Windows 2008 R2 platform, which is accessed via OLEDB since there is no Access to SQL Server on Windows (for some strange reason). If anyone wants to do this then the following instructions can be used to change a library to use uncommitted reads. Open SAS Management Console Go to Data Library Manager Select Libraries Locate the desired library of type OLEDB (e.g. IDM) and double click Select Options tab Press the Advanced Options button Select Locking tab Select Isolation Level for Reading Set to RU (Read Uncommitted) If you are using your own libname statements then you would use the read_isolation_level parameter ... SAS/ACCESS(R) 9.2 for Relational Databases: Reference, Fourth Edition Beware though that this might not perform well if you are joining data from some libraries that use this and some that dont... SAS/ACCESS(R) 9.3 for Relational Databases: Reference, Second Edition thanks Phil Mason ... View more