Consider a table T in a relational database with a key field K. A B-tree of order p is used as an access structure on K, where p denotes the maximum number of tree pointers in a B-tree index node. Assume that K is 10 bytes long; disk block size is 512 bytes; each data pointer P_D is 8 bytes long and each block pointer P_B is 5 bytes long. In order for each B-tree node to fit in a single disk block, the maximum value of p is

Consider the following schedule S of transactions T1 and T2: Which of the following is TRUE about the schedule S?

Which level of locking provides the highest degree of concurrency in a relational database?

Let R₁ (A, B, C) and R₂ (D, E) be two relation schema, where the primary keys are shown underlined, and let C be a foreign key in R₁ referring to R₂. Suppose there is no violation of the above referential integrity constraint in the corresponding relation instances r₁ and r₂. Which one of the following relational algebra expressions would necessarily produce an empty relation?