Hi,
I have a strange query compilation issue which is hard to reproduce. It only happens under high load and cannot be easily repeated.
- There is a table T with columns A,B,C,D.
- There is a non-unique clustered index on T(A, B, C, D).
- There is a query SELECT * FROM T WHERE A=@P1 AND B=@P2 AND (C=@P3 OR C=@P4) AND D=@P5. The seek condition is on all columns of the clustered index, the 3-rd column has an OR.
The problem is that the query plan for this query has Seek Predicate only on A and B! The predicate on C and D is an ordinary predicate, so this means that search tree on columns C and D is not utilized.
Could anyone provide any hints on why this could be happening? SQL version is 2008 R2 (SP1) - 10.50.2789.0 (X64)
