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CUSTOMER_CODE SMUDE DIVISION_CODE SMUDE EVENT_CODE APR2016 ASSESSMENT_CODE MCA3020_APR2016 QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 18253 QUESTION_TEXT Explain Temporal Database and Multimedia Database. SCHEME OF EVALUATION Temporal Database: Temporal databases are used to record timereferenced data. Basically, majority of the database technologies are temporal. For example: Record keeping function (inventory administration, medical-record and personnel); Financial function (banking, accounting and portfolio organization); Scientific function (Weather monitoring), Scheduling function (project organization, hotel, airline, and train reservations) all these functions trust on temporal databases. (2 marks) Temporal databases are best suited for the applications where information as to organize on time constraints. Therefore temporal database set a good example to demonstrate the requirement for development of a combined set of concepts for the use of application developers. The training of temporal database is designed by application developers and designers. There are numerous applications where time is an important factor in storing the information. For example: Insurance, Healthcare, Reservation Systems, and Scientific Databases. (2 marks) In case of temporal applications, even the two instances utilized might be simply expanded. For example, in COMPANY database, it might be desirable to keep PROJECT, JOB, and SALARY histories of all the employees. It can be applied to UNIVERSITY database as well, to store the grade history of STUDENT. The details about the YEAR, SEMESTER, COURSE and each SECTION are also included in this database.(1 mark) Multimedia Database: Multimedia databases facilitate the users to store as well as generate query for retrieving multimedia information. This information can demand for: Documents (like articles/books/journals), Images (like drawings/pictures), Video Clips (like newsreels/movies/hone videos); Audio clips (like speeches/ phone messages/ songs).(1 mark) The primary type of database query generally tries to locate multimedia sources comprising of particular objects of interest. Such as, one user wants to locate all the video clips regarding aa specific person, say Michael Jackson in a video database. Another scenario may be as of someone willing to retrieve video clips grounded on specific activities like, video clips where a soccer goal is scored by a certain player or team. These type of queries are mentioned as content based retrieval, as they retrieve information bases on a certain activity/object from the multimedia sources. (2 marks) To make this retrieval fast, the multimedia database must make use of some model to index and manage multimedia sources grounded on the contents. But identifying the contents of multimedia sources is lengthy and difficult task. To accomplish this task, two approaches can be followed as defined below: 1.Based on automatic analysis of the multimedia sources. It is done to recognize the contents mathematical characteristics. 2.Based on manual identification of the objects and objectives of interest in each multimedia source. And later on depending on this information index the sources. (2 marks) QUESTION_T DESCRIPTIVE_QUESTION YPE QUESTION_ID 73630 QUESTION_T Discuss any five SQL features in detail. EXT 5 features - >2 marks each. Any 5 features among those mentioned below SCHEME OF EVALUATION may be written QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 73632 QUESTION_TEXT What is database recovery management? Discuss three levels of backup. State the methods and characteristics of transaction recovery. SCHEME OF EVALUATION Definition – 1 mark 3 level – 3 marks 4 methods – 4 marks 2 characteristics – 2 marks Data recovery is concerned with the restoring of database to an accurate state in the occurance of a failure. Levels: • full database backup (considers full backup of database) • Differential back up (only the last variations that are performed on the database are copied) Transaction log backup (to back up those operations that are not shown in a preceding backup copy of the database) Methods: - • write ahead protocol (makes sure that transaction logs are always written before any database data that are really updated) • Redundant transaction loga (make sure that a disk physical failure will not harm the DBMS ability for recovering data • Database buffers (used to accelerate disk operations) • Database checkpoint (all updated buffers are written to the disk by the DBMS) Characteristics:• deferred write and deferred update (used by recovery process sothat the transaction operations do not update the physical database instantly) • Write through (database is instantly updated by transaction operations throughout the transaction’s execution, even before the transaction arrives at its commit point) QUESTION_T DESCRIPTIVE_QUESTION YPE QUESTION_ID 73633 QUESTION_T What is data partitioning? What are the types of partitioning techniques? Compare the various techniques. EXT Definition – 1 mark I/O parallelism (Input/output parallelism) is the simplest type of parallelism. This parallelism attempts to minimise the time required to retrieve relations from disk by partitioning the relations on multiple disks. In this the input data is partitioned and thereafter each partition is processed in parallel. The results obtained are then combined after the processing of all partitioned data. This technique greatly reduces the retrieval time. I/O parallelism is also referred to as data partitioning. 3 types – 2 marks eachcomparison – 3 marks Method in which rows acted on by the operation must be partitioned SCHEME OF between the query server processes. EVALUATION Types:- round robin (simple approach, best when all applications want to access relation by scanning sequentially all of it on each and every query; however not suitable for sophisticated access of the relation) • Hash partitioning (select attributes as partitioning attributes. Helps to avoid data skew. Suitable for applications which want only associative and sequential access to data. Tuples are positioned by applying a hashing function to any one attribute of each tuple) • Range partitioning (the administrator chooses an attribute as the partitioning attribute and specifies attribute values within a certain range to be placed on certain disk. Helps to distribute a contiguous attribute value ranges to each disk. Effective for grouping data and also sequential and associative access) Comparison QUESTION_TYP DESCRIPTIVE_QUESTION E QUESTION_ID 125273 QUESTION_TEX Write a short note on Buffer Management. T SCHEME OF EVALUATION SQL Server uses buffer pages for any changes or requests for the data on the database. These buffer pages are 8KB pages on RAM that minimizes disc Input/Output. Any 8KB page can be buffered in memory, and set of all pages currently buffered is called as buffer cache. The amount of memory available to SQL Servers decides how many pages will be cached in memory. The buffer cache is managed by Buffer Manager. Either reading from or Writing to any page on the disc happens at two levels. The data that should be either read/Written is first copied to the buffer cache and the read/write operation is carried out on the data that is currently on the Buffer Cache. The edited data is updated on the disc by the buffer manager only if the in-memory cache has not been referenced for some time. While writing pages back to the disc, asynchronous I/O is used whereby the I/O operation is done in a background thread so that other operations do not have to wait for the I/O operation to complete. Each page is written with a checksum while they are written to the disc so that while the data is referred back any time, the checksum mismatch would detect the corruption of the data. Data must be in RAM for DBMS to operate on it! Buffer Mgr hides the fact that not all data is in RAM Bufferpool information table contains: <frame#, pageid, pin_count, dirty> If requested page is not in pool: Choose a frame for replacement. Only “un-pinned” pages are candidates! If frame is “dirty”, write it to disk Read requested page into chosen frame Pin the page and return its address Requestor of page must eventually unpin it, and indicate whether page has been modified: dirty bit is used for this. Page in pool may be requested many times, a pin count is used. To pin a page, pin_count++ A page is a candidate for replacement iff pin count == 0 (“unpinned”) CC & recovery may entail additional I/O when a frame is chosen for replacement. Write-Ahead Log protocol; s 10mark QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 125275 QUESTION_TEXT Discuss Semantic Query Optimization. What are the various Execution Strategies for SQL Sub Queries? SCHEME OF EVALUATION Semantic Query Execution: Semantic Query Execution is a technique to modify one query into another query by using the relational database constraints. These constraints may be unique attributes or much more complex constraints. This technique is used for the efficient execution of the query. (1 mark) Consider the example below: Select E.LNAME, M.LNAME FROM EMPLOYEE AS E, EMPLOYEE AS M WHERE E.SUPERNO=M.ENO AND E.SALARY>M.SALARY marks) (2 This query retrieves the names of employees who earn more than their supervisors. If a constraint is applied on the database schema to check that none of the employee can earn more than his reporting supervisor; the semantic query optimizer checks for this constraint and may not execute the query if it knows that the resultant query will be empty. If the constraint check is done efficiently then this approach can save a lot of time. (2 marks) Execution Strategies for SQL Sub Queries: Different physical execution strategies are employed by query optimizer for the various logical query plan options. Two types of strategies are there for sub query execution: 1. Navigational Strategies 2. Set-Oriented Processing (1 mark) 1. Navigational Strategies: For executing sub-query, navigational strategies depends on the nested loops joins. Basically there are two classes of navigational strategies: forward lookup and reverse lookup. Forward lookup firstly starts executing the outer query and when outer rows are generated then it invokes the sub-query. Reverse lookup starts with the sub-query and processes one sub-query row at a time. (2 marks) 2. Set-Oriented Processing: Set-Oriented Processing finally needs that the query could be effectively de-correlated. If this is the situation, set operations for example hash, merge and join can execute the query. (2 marks)