I am reading this: http://www.sql-server-performance.com/2013/how-to-optimize-sql-server-query-plan/
it said many thing I don't understand:
1) analyze query plan with profiler! how can profiler analyse query plan ? profiler can use to check what has been ran. but analyzes query plan is .... ?
2) "so we can drop IDENTITY column in favor of a composite primary key:", what is the relationship ?
3) "To avoid the table spool reading, let’s try to rewrite this query by using ROW_NUMBER:", what is the use of row_number there that can take out the spool ?