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CUSTOMER_CODE SMUDE DIVISION_CODE SMUDE EVENT_CODE OCTOBER15 ASSESSMENT_CODE BT0066_OCTOBER15 QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 4499 QUESTION_TEXT Explain various storage devices and their characteristics. SCHEME OF EVALUATION 1.Cache: The cache is the fastest and most costly form of storage. Cache memory is small; its use is managed by computer system hardware. We shall not concern about managing cache storage in the database system. 2.Main memory: The storage medium used for data is available to be operated on is main memory. The general purpose machine instructions operate on main memory. Although main memory may contain many megabytes of data, it is generally too small for storing the entire database. The contents of main memory are usually lost if a power failure or system crash occurs. 3.Magnetic–disk storage: The primary medium for the long-term on-line storage of data is the magnetic disk. Usually the entire database is stored on magnetic disk. The system must move the data from disk to main memory so that they can be accessed. After the system has performed the designated operations, the data that have been modified must be written to disk. 4.Flash memory: It offers from main memory in that data survive power failure. Reading data from flash memory takes less than 100 nanoseconds which is roughly as fast as reading data from main memory. It is also known as erasable programmable read only memory(EEPROM) 5.Optical storage: The most popular forms of optical storage are the compact disks (CD) which can hold about 640 megabytes of data and the digital video disk (DVD) which can hold about 4.7 or 8.5 gigabytes of data per side of the disk. Data are stored optically on a disk and are read by a laser. The optical disks in read only compact disks (CD-ROM) or read only digital video disk (DVD-ROM) cannot be written but are supplied with data prerecorded. 6.Tape storage: Tape storage is used primarily for backup and archival data. Although tape is much cheaper than disks access to data is much slower, because the tape must be accessed sequentially from the beginning. For the reason tape storage is referred to as direct access storage because it is possible to read data from any location on disk. (Any five Storage devices, 2x5=10 marks) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 73048 QUESTION_TEXT Explain magnetic disks along with its physical characteristics, performance measures & optimization of disc block access. Magnetic Disks The magnetic disks facilitate the bulk of secondary storage. In the modern computer systems the storage capacity requirements have been growing at over 50 percent per year. Physical Characteristics of Disks SCHEME OF EVALUATION Each disk platter has a flat circular shape. Its two surfaces are covered with a magnetic material, and information is recorded on the surfaces. Platters are made from rigid metal or glass and are covered (usually on both sides) with magnetic recording material. The disk surface is logically divided into tracks, which are subdivided into sectors. A sector is the smallest unit of information that can be read from or written to the disk. Performance Measures of Disks The quality of a disk can be measured by its access time, capacity, reliability and data-transfer-rate. Access time is the time from when a read or write request is issued to when data transfer begins. 4 Optimization of Disk-Block Access In most of the operating system the disk I/O request generated by file system and by virtual memory manager. Here the request provides address on the disk and this address is in the form of a block number. A block is a contiguous sequence of sectors from a single track of one platter. QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 73050 QUESTION_TEXT Explain embedded SQL & explain embedded SQL statements. SCHEME OF EVALUATION 6 Embedded SQL So far we treated SQL as independent language and also various types of SQL query construct. There is an interactive interface for relational DBMS, which facilitate many users to enter SQL commands directly. This approach is fine as long as the tasks which need to be performed purely on SQL commands. There are few situation arises where we require these languages beyond the data manipulation only… Embedding SQL Statements A host program can have any number of SQL statements provided it must be clearly marked and details about these statements. In C, EXEC SQL is pre-fixed to SQL statements. We can place SQL statement can appear any place in the host program. QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 118244 QUESTION_TEXT What are the update statements used in database? Explain. Insert Delete SCHEME OF EVALUATION Update (1 mark) Explain each with example 3*3=9 marks QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 118249 QUESTION_TEXT Discuss the various Normal forms of a relation. ● 1NF ● 2NF ● 3NF ● 4NF ● 5NF ● BCNF (10 marks) SCHEME OF EVALUATION QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 163209 QUESTION_TEXT List and explain the relational database components. Relational database components include: Table Row SCHEME OF EVALUATION Column Field Primary key Foreign key