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Define Query Processing
Query processing is the process of selecting the best plan or strategy to be employed in responding to a database request. The plan is then executed to produce a response. The component of the DBMS accountable for generating this strategy is known as a query processor. It is a step by step process. The first or initial step is to transform the query into a standard from. For instance, a query in QBE looked into by the research community. Query might be transformed into a relational algebraic expression; the optimization is carried out by substituting equivalent expressions for those in the query. In the next step a number of strategies known as access pans are generated for evaluating the transformed query. The physical characteristics of the data and any supporting access method are taken into account in producing alternate access pans. The cost of each access plan is calculated and the optimal one is selected and executed.
Identification of concurrency Identification of concurrency: Dynamic model identifies concurrency. Two objects are said to be parallel (concurrent) if they can receive events a
distributed quey processing
Objectives After reading this part, you should be able to: Modify, create, and delete database schema objects; Update database using SQL command; Retrieve data f
Define the Query optimisation The query parser commonly generates a standard initial tree to correspond to an SQL query, with no doing any optimization. Such type of a canonica
Hashed File Organisation Hashing is the most common form of purely random access to a database or file. It is also used to access columns that do not have an index as an optimi
What is self-transition? If there is a transition which goes back to same state, it is known as "self- transition." With a trigger action exit action would be executed f
What is known as clustering file organization? In the clustering file organization, records of several dissimilar relations are stored in the similar file.
Whenever the LIMIT clause will be used? LIMIT is used for the following kinds of problems: 1) Answering questions about first or last and largest or smallest 2) Splitting
Write short notes on Schema diagram. A database schema along with primary key and foreign key dependencies can be depicted pictorially by schema diagram. Every relation appears
Critically evaluate the bulleted list of information-related items in this case study. How are each contradictory to the notion of being an information-literate knowledge worker?
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