Indexes interview questions and answers in Oracle sql.

-
What is index?

It is a separate database object which is associated with the table. It speeds up data retrieval by providing faster access path to the data. It acts like an index in the book. It allows the database to quickly locate and retrieve the fastest access path to the data. It allows the database to quickly locate and retrieve the rows based on the indexed columns.

Key features:

It is used for faster retrieval data. It allows the database to find the specific row in the database more quickly. It will return the small portion of the table rows.


How to create index?

What are the types of index?

Explain binary tree index?

Explain bitmap index?

Explain function-based index?

Explain reverse key index?

When to choose what type of index?

  How to know index is being used?

How to monitor index usage?

What are the benefits and drawbacks of index?


Comments

Post a Comment

Popular posts from this blog

Difference between union and union all in oracle sql plsql

-
Image
"This is one of the most important questions that interviewer might be asking in an interview.Infyosis,Linked group,Kyndryl,Vodafone Idea, IBM and Mphasis etc." INTRODUCTION: It is said to be set operators which is used to combine, add or concatenate two or more result sets. It is used in the multiple select statements where to combine to produce the final desired results. In other words, multiple select statements of similar column name in same order and having same data type to produce the unified result. It merges the content of the two structurally compatible organized tables into single table.  In MIS datalake,when you are adding the modules of GST reconciliation which is to be used in micros in Excel or VB script, union and union all set operator is preferred for eliminating duplicate records or keeping duplicate records as per business requirement. There are several alternatives like bulk collect,join,set operators like intersect & minus for combining the data from...
Read more

Explain oracle pl sql datatypes interview question and answer for fresher and experienced.

-
Image
 Oracle PLSQL Data Types : PLSQL constant,value,variable,parameter,function which return the value are having the data type. It will determine the storage space information occupied and occurred in the memory or storage format and range constraints for valid values and operations as per specified size limit. It will determine how the data will be going to stored, handled and treated by the oracle engine during the period of processing and storage. It is used in the PLSQL blocks. It allows you to define your sub-types. PLSQL codes are embedded into the java program. Subtypes are used to make the data types compatible with data types used in the PLSQL program while embedding the PLSQL code into the java program. Subtype will be compatible with ANSI/ISO & IBM. It provides the pre-defined data types. Pre-defined data types are categorized into the four types: Composite LOB Reference Scalar Scalar Datatypes: It stores the values without the internal components. It holds the single ...
Read more

Difference between full join and cross join-oracle sql plsql

-
Image
 Difference between full join and cross join in sql:- They behave differently to combine the rows from the two tables. FULL OUTER JOIN: It is also called as the full join .It will return all the rows when there is either match in the left table or right table. If there is no match, it will return NULL for the rows of the columns which is lacking the matching rows. Syntax: select c.*,d.*  from tableC c FULL OUTER JOIN tableD d on c.id=d.id; select e.ename,d.dname from emp e FULL OUTER JOIN dept d ON e.deptno=d.deptno; When you want to retain the unmatched rows i.e operations which is not present in the emp table and having deptno as 40.So,ename is appeared as NULL. CROSS JOIN: It returns the cartesian product of both the tables i.e. Every row of the table A is combined with every row of the table B.ON condition is not used due to not match rows. Syntax: select c.*.d.* from tableC c CROSS JOIN tableD d; select e.ename,d.dname from emp e CROSS JOIN dept d; ENAME ...
Read more