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a) Suppose we updated the catalog tables in real time, that is, after every update, insert, or delete SQL statement were executed-rather than only running RUNSTATS once every few days or longer.
Is this idea (real time updates), a good idea? Provide arguments both for and against.
b) Suppose the DBMS kept track of how long it took to execute each SQL statement: i.e., for every single SELECT, INSERT, UPDATE, and DELETE statement. Explain how the database system could use this information in some meaningful and practical ways to suggest to the DBA when it is time to reorganize the tables and indexes (or for the DBA to take other action).
c) When should a DBA consider dropping indexes from a table? Give at least 3 good reasons.
Nested Queries Let us see some more complex queries in this section. Sub-queries: Some of the basic concerns of sub-queries are: A sub-query is a SELECT statemen
What is system catalog or catalog relation? How is better known as? A RDBMS maintains a explanation of all the data that it contains, information about every relation and index
What is meant by data-transfer rate? The data-transfer rate is the rate at which data can be retrieved from or kept to the disk.
Consider a systems development project with the following data Activity Duration (weeks) Precedence Relationship 1. Software design
Suppose that in an organisation, an employee may do different roles in dissimilar projects. Say, RAM is doing coding in one project and doing designing in another. Suppose that the
Multiple column Queries: Syntax: SELECT COLUMN1, COL2,...... FROM TABLE WHERE (COLUMN1, COL2, ...) IN (SELECT COLUMN1, COL2,.... FROM TABLE WHERE );
Problem : (b) A deductive database system is essentially the outcome of applying mathematics logic to database management, where logic is used for both data representation and
Explain Record Based Logical Models? Record-Based logical Models: Also define data at the conceptual and view levels. Unlike object-oriented models, are used to state overall
Example RELATION SCHEMA for STUDENT: STUDENT (Roll No: string, name: string, login: string, age: integer) RELATION INSTANCE
Describe the four main ways of optimising disk block access. Ans: a. Disk b. Non-volatile writes buffers c. File organization (Clustering) d. Log-based file system
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