Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
What is an Index?
An index is a small table having only two columns. The first column has a copy of the primary or candidate key of a table and the second column having a set of pointers holding the address of the disk block where that particular key value can be found.
The advantage of using index lies in the fact is that index makes search operation perform very fast. Suppose a table has a several rows of data, each row is 20 bytes wide. If you want to search for the record number 100, the management system must thoroughly read each and each row and after reading 99x20 = 1980 bytes it will search record number 100. If we have an index, the management system starts to search for record number 100 not from the table, but from the index. The index, having only two columns, might be just 4 bytes wide in each of its rows. After reading only 99x4 = 396 bytes of data from the index the management system search an entry for record number 100, reads the address of the disk block where record number 100 is stored and directly points at the record in the physical storage device. The result is a much faster access to the record (a speed benefit of 1980:396).
Explain Dynamic Two-Phase Locking Here a transaction locks a data item instantly earlier than any operation is applied on the data item. After finishing all the operations on
Mappings between Levels and Data Independence The 3 levels of abstraction in the database do not exist separately of each other. There must be some correspondence, or mapping
In E-R diagram how generalization is represented? in E-R diagram generalization is represented by Triangle shape.
Consider the E/R schema with weak entity sets shown below. Come up with the SQL CREATE TABLE statements (with appropriate primary key, unique and foreign key constraints). Include
How can one distinguish among different kinds of parameters? Input parameters are used to pass data to subroutines. Output parameters are used to pass data from subrout
What is a guard condition? Explain it with a suitable example. The guard-condition is a Boolean expression written with respect to parameters of triggering event and attributes
What are the situations while DBMS should not be used? DBMS should not be used in situations like: (i) No need of security. (ii) Not difficulty to access the data (iii) N
What are advantages of object models? Object models are efficient for communicating with the application experts and reaching a consensus about the significant aspects of the p
Which sorting technique is used to sort databases, whose sizes are very big? Give one such algorithm. Why do sorting techniques like quicksort, insertion sort, etc. not applied
DDL Compiler The DDL compiler changes the data definition statements (such as CREATE TABLE .... in SQL) into a set of tables having metadata tables. These tables have infor
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd