DBMS Unit 4 Part 8 Concurrency Control Techniques

Que5.21. bandy multiversion two- phase locking. Answer 1. The multiversion two- phase locking attempts to combine the advantages of multiversion concurrency control with the advantages of two- phase locking. 2. In addition to read and write cinch modes, multiversion two- phase locking provides another cinch mode, i.e., certify. 3. In order to determine whether these cinch modes are compatible with each other or not, considerFig.5.21.1 5.21.1. comity matrix for multiversion two- phase locking. 4. The term “ YES ” indicates that if a sale Ti hold a cinch on data item Q than cinch can be granted by other requested sale Tj on same data itemQ. 5. The term “ NO ” indicates that requested mode isn’t compatible with the mode of cinch held. So, the requested sale must stay until the cinch is released. 6. In multiversion two- phase locking, other deals are allowed to read a data item while a sale still holds an exclusive cinch on the data item. 7. This is done by maintaining two performances for each data item i.e., certified interpretation and uncertified interpretation. 8. In this situation, Tj is allowed to read the pukka interpretation of Q while Ti is writing the value of uncertified interpretation ofQ. still, if sale Ti is ready to commit, it must acquire a certify cinch onQ. Que5.22. What are the problems that can arise during concurrent prosecution of two or further deals? bandy styles to help or avoid these problems. Answer Problems that can arise during concurrent prosecution of two or further sale relateQ.5.11, Page 5 – 10A, Unit- 5. styles to avoid these problems 1. Cinch grounded protocol a. It requires that all data particulars must be penetrated in a mutually exclusive manner. b. In this protocol, concurrency is controlled by locking the data particulars. c. A cinch guarantees exclusive use of a data item to current sale. Cinches are used as a means of coinciding the access by concurrent sale to the database particulars. Que5.23. Explain the recovery with concurrent deals. Answer Recovery from concurrent sale can be done in the following four ways 1. Interaction with concurrency control a. In this scheme, the recovery scheme depends greatly on the concurrency control scheme that’s used. b. So to rollback a failed sale, we must undo the updates performed by the sale. 2. sale rollback a. In this scheme we rollback a failed sale by using the log. b. The system scans the log backward, for every log record set up in the log the system restores the data item. 3. Checkpoints a. In this scheme we used checkpoints to reduce the number of log records that the system must overlook when it recovers from a crash. b. In a concurrent sale recycling system, we bear that the checkpoint log record be of the form, where ‘ L’ is a list of deals active at the time of the checkpoint. 4. renew recovery a. When the system recovers from a crash, it constructs two lists. b. The undo- list consists of deals to be undone, and the redolist consists of sale to be redone. c. The system constructs the two lists as follows originally, they are both empty. The system scans the log backward, examining each record, until it finds the first record. Que5.24. Describe Oracle. How data is stored in Oracle RDBMS? Answer 1. The Oracle database( generally appertained to as Oracle RDBMS or simply Oracle) consists of a relational database operation system( RDBMS). 2. Oracle is amulti-user database operation system. It’s a software package specializing in managing a single, participated set of information among numerous concurrent druggies. 3. Oracle is one of numerous database waiters that can be plugged into a customer/ garçon equation. 4. Oracle works to efficiently manage its resource, a database of information, among the multiple guests requesting and transferring data in the network. Storage 1. The Oracle RDBMS stores data logically in the form of table spaces and physically in the form of data lines. 2. Table spaces can contain colorful types of memory parts, similar as data parts, indicator parts,etc. Que5.25. Write the name of fragment lines used is Oracle. Explain database schema. Answer Fragment lines consists two lines which are as follows 1. Data lines a. At the physical position, data lines comprise one or further data blocks, where the block size can vary between data lines. Data lines can enthrall pre-allocated space in the train system of a computer garçon, use raw fragment directly, or live within ASM logical volumes. 2. Control lines One( or multiple multiplexed) control lines( also known as “ control lines ”) store overall system information and statuses. Database schema 1. Oracle database conventions relate to defined groups of object power as schemas. 2. utmost Oracle database installation has a dereliction schema called SCOTT. 3. After the installation process has set up the sample tables, the stoner can log into the database with the username scott and the word barracuda. 5. The SCOTT schema has seen lower use as it uses many of the features of the more recent releases of Oracle. 6. utmost recent exemplifications supplied by Oracle Corporation source the dereliction HR or OE schemas. Que5.26. Define in terms of Oracle Tablespace ii. Package iii. Schema Answer Tablespace 1. A tablespace is a logical portion of an Oracle database used to allocate storehouse for table and indicator data. 2. Each tablespace corresponds to one or further physical database lines. 3. Every Oracle database has a tablespace called SYSTEM and may have fresh tablespaces. 4. A tablespace is used to group related logical structures together. ii. Package 1. Packages are a system of recapitulating and storing affiliated procedures, functions, and other package constructs together as a unit in the database. 2. It also offers increased functionality and database performance. 3. Calling a public procedure or function that’s part of a package is no different than calling a standalone procedure or function, except that we must include the program’s package name as a prefix to the program name. iii. Schema 1. A schema is a collection of table delineations or affiliated objects possessed by one person or stoner. 2. SCOTT is schema in the Oracle database. 3. Schema objects are the logical structures that directly relate to the database’s data. 4. Schema objects include similar structures as tables, views, sequences, stored procedures, antonyms, indicators, clusters and database links. Que5.27. Explain SQL Plus, SQL * Net and SQL & haul. Answer SQL Plus 1. SQL Plus is the frontal end tools for Oracle. 2. The SQL Plus window looks important like a DOS window with a white background analogous tablet. 3. This tool allows us to class in our statements,etc., and see the results. SQL * Net 1. This is Oracle’s own middleware product which runs on both the customer and garçon to hide the complexity of the network. 2. SQL * Net’s multiprotocol cloverleaf allows customer/ garçon connections to span multiple communication protocols without the need for islands and routers,etc., SQL * Net will work with any configuration design. SQL * haul 1. A mileage used to load data from external lines into Oracle tables. 2. It can load data from as ASCII fixed- format or demarcated train into an Oracle table. Que5.28. What do you mean by locking ways of concurrency control? bandy the colorful locking ways and recovery with concurrent sale also in detail. Answer Locking ways 1. The locking fashion is used to control concurrency prosecution of deals which is grounded on the conception of locking data particulars. 2. The purpose of locking fashion is to gain maximum concurrency and minimal detention in processing deals. 3. A cinch is a variable associate with a data item in the database and describes the status of that data item with respect to possible operations that can be applied to the item; there’s one cinch for each data item in the database.

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