Creation of indexes, Database Management System

Assignment Help:

Creation of Indexes

Automatically: When a primary key or Unique constraint is show in a table definition then a unique index is formed automatically.

Manually: User can form non-unique indexes on columns to speed up access time to rows.

Example: The following commands produce index on employee name and employee name + department number respectively.

CREATE INDEX EMP_ENAME_IDX ON EMP (ENAME);

CREATE INDEX EMP_MULTI_IDX ON EMP (ENAME, DEPTNO);

Finding facts about created indexes: The data dictionary have the name of index, table name and column names. For instance, in Oracle a user-indexes and user-ind-columns see contains the details about user formed indexes.

Remove an index from the data dictionary:

DROP INDEX EMP_ENAME_IDX;

Indexes cannot be modified.


Related Discussions:- Creation of indexes

xml, basic structure of xm

basic structure of xml

Discuss the different layers of ansi sparc architecture, Q.1 Briefly discus...

Q.1 Briefly discuss the different layers of ANSI SPARC architecture. Ans: The three layers of ANSI SPARC architecture are like this: 1. Internal view is at the lowest leve

One-to-many relationship, For each 1: n relationship type R involving two e...

For each 1: n relationship type R involving two entities E1 and E2, we recognize the entity type (say E1) at the n-side of the relationship type R and contain primary key of the en

Explain candidate key, Explain Candidate key? Candidate Key - A candi...

Explain Candidate key? Candidate Key - A candidate key is a minimal superkey, that can be used to uniquely identify a tuple in the relation.

Mr.dattu, Define a job scheduling strategy that will meet business requirem...

Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pictori

Explain the acid properties of a transaction, Explain the ACID properties o...

Explain the ACID properties of a transaction Ans: ACID properties are a significant concept for databases. The ACID stands for Atomicity, Consistency, Isolation, and Durability

Primary index, Primary index A primary index is a file that has a sorte...

Primary index A primary index is a file that has a sorted series of records having two columns: a block address for that key field in the data file; and the ordering key field.

Security-drawbacks of data distribution, Security: In a centralised system...

Security: In a centralised system, access to the data can be simply controlled. Though, in a distributed DBMS not only does access to replicated data have to be controlled in many

Approach to implement traffic data management, There are many simple and co...

There are many simple and complex approaches to implement. These reports are based on some views or certain query. The following number of reports can be built. 1. The averag

What are the kinds of strings, What are the kinds of Strings?  -A binar...

What are the kinds of Strings?  -A binary string in MySQL is one that MySQL treats as case sensitive in comparisons. -A non binary string in MySQL is one that MySQL does'nt

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd