Ramakrishnan and Gehrke Solutions-185-199

CSC 472 Introduction to Database Systems Project Which of the following is FALSE regarding "sequential flooding"? Group of answer choices The LRU replacement policy is susceptible to sequential flooding. The sequential flooding pollutes the buffer pool with pages that are read once and then never again. The sequential flooding is caused by a query performs a sequential scan that reads every page. The CLOCK replacement policy is immune from the sequential flooding.

Another action may be triggered by the execution of a trigger. There is often a limit on how deep nesting may go in database systems. Why could they impose such a restriction?

2. DEL Transactions: The following transaction schedule is given. A,B,C are the addresses of the records in the database and T1, T2 and T3 are the transactions. T1 R(A)W(A) R(C) R(B)W(B)C T2 T3 R(B) W(B) R(C) R(B)W(B) R(A) с a) Show an example of a strict 2PL implementation that leads to a deadlock b) For a) draw a >>wait-for<< graph c) Avoid the previously drawn deadlock with a wait-die<< policy d) Give an example of another schedule that would be conflict-equivalent to the given schedule of transactions W(A)C

131. In concurrency control policy the the lock is obtained on a. Entire database b. A particular transaction alone c. All the new elements d. All of the mentioned

In a database system, the allocation of records to blocks has a significant impact on its performance.

Describe how if certain log entries for a block are not created to stable storage before the block is written to disk, the database may become inconsistent.

Can clustering of files occur after the files are populated with records?

2. DEL (30 %): Transactions:The following transaction schedule is given. A,B,C are the addresses of the recordsin the database and T1, T2 and T3 are the transactions.T1    R(A)W(A)     R(C)                                                 R(B)W(B)C-----------------------------------------------------------------------------------------------------------------T2                       R(B)      W(B)                          R(A)                           W(A)C-----------------------------------------------------------------------------------------------------------------T3                                 R(C)         R(B)W(B)                             Ca) Show an example of a strict 2PL implementation that leads to a deadlockb) For a) draw a »wait-for« graphc) Avoid the previously drawn deadlock with a »wait-die« policyd) Give an example of another schedule that would be conflict-equivalent to thegiven schedule of transactions

Inserting data into a flat-file database is very straightforward and usually amounts to simply tacking the new data onto the end of the data file. For example, inserting a new megalith record into a colon-

True or false

Compute total no of blocks} Consider a file of 8192 records. Each record is 16 bytes long and its key field Is of size 6 bytes. The file is ordered on a key field, and the file organization is unspanned. The file is stored in a file system with block size 512 bytes, and the size of a block pointer is 10 bytes. If the primary index is built on the key field of the file, and a multilevel index scheme is used to store the primary index, number of first-level and second level blocks in the multilovel index are the respectively 16 and 1 b. 32 and 1 16 and 2 8 and 1 c. d.

One option for protecting a bank's database is a snapshot isolation scheme. In certain cases, the bank may encounter difficulties due to an execution that cannot be serialized.

Consider a file of 16384 records. Each record is 32 bytes long and its key field is of size 6 bytes. The file is ordered on a non-key field, and the file organization is unspanned. The file is stored in a file system with block size 1024 bytes, and the size of a block pointer is 10 bytes. If the secondary index is built on the key field of the file, and a multilevel index scheme is used to store the secondary index, the number of first-level and second-level blocks in the multilevel index are respectively

Determine whether the following statements are true or false    a)Once a transaction is committed, it cannot be rolled back. Answer: b) An index file is always larger than the original database file because the index file needs to store an additional pointer to each record. Answer: c) Sparse indices facilitate faster search operations comparing to the dense indices. Answer: d) In a B+-tree, it always requires reorganizing the entire index file to maintain performance. Answer: e) Atomicity of transactions means that the transaction must be executed serially. Answer: f) Both committed and aborted transactions leave the database in consistent state. Answer: g) A serial schedule always satisfies isolation requirement. Answer: h) If P is the primary key of schema R, we must have P ® R. Answer: I) A failed transaction must be aborted. Answer: j) If the precedence graph of a schedule is acyclic, the schedule is serializable. Answer:

True/False: Rollback refers to the reversing of database changes.