Consider the following statements.
S1 : The sequence of procedure calls corresponds to a preorder traversal of the activation tree.
S2 : The sequence of procedure returns corresponds to a postorder traversal of the activation tree.
Which one of the following options is correct?
Suppose a database system crashes again while recovering from a previous crash. Assume checkpointing is not done by the database either during the transactions or during recovery.
Which of the following statements is/are correct?
Consider a linear list based implementation in a file system. Each directory is a list of nodes, where each node contains the file name along with the file metadata, such as the list of pointers to the data blocks. Consider a given directory foo.
Which of the following operations will necessarily require a full scan of foo for successful completion?
A relation r(A, B) in a relational database has 1200 tuples. The attribute A has integer values ranging from 6 to 20, and the attribute B has integer values ranging from 1 to 20. Assume that the attributes A and B are independently distributed. The estimated number of tuples in the output of σ(A>10)∨(B=18)(r) is ______