SQL Server performance for tables having large number of columns I have a requirement where I need to create a table with about 600 columns. Out of 600 columns about 200 columns will be XML columns. Other column will be of other datatypes such as int, varchar, nvarchar etc.  

Also about 50% XML column will have about 40 to 60 rows and other will have less number of rows. The entire table will have about 2000 to 3000 rows. Theoretically SQL allows maximum of 1024 columns. But what will be the performance in my scenario? Does this design will effect performance?

Also does SQL Server have limitation for row size?
If a table has 600 columns it is a very good idea to review the database design. You could move several columns into separate tables, especially the ones with 98% and more NULL values.

Also you will run into trouble if your row does not fit into a single page any more. (see here.)