What Is An INDEX & What are Types of INDEX | SQL Tutorials



An index is a performance-tuning method of allowing faster retrieval of records. An index creates an entry for each value that appears in the indexed columns. By default, Oracle creates B-tree indexes.

Syntax of Index Creation.
The syntax for creating a index is:
CREATE [UNIQUE] INDEX index_name
  ON table_name (column1, column2, . column_n)
  [ COMPUTE STATISTICS ];
UNIQUE indicates that the combination of values in the indexed columns must be unique.

Create a Function-Based Index: In Oracle, you are not restricted to creating indexes on only columns. You can create function-based indexes too.

The syntax for creating a function-based index is:

CREATE [UNIQUE] INDEX index_name
  ON table_name (function1, function2, . function_n)
  [ COMPUTE STATISTICS ];

Types of index data structures can you have

An index helps to faster search values in tables. The three most commonly used index-types are: -

B-Tree: builds a tree of possible values with a list of row IDs that have the leaf value. Needs a lot of space and is the default index type for most databases. 

Bitmap: string of bits for each possible value of the column. Each bit string has one bit for each row. Needs only few space and is very fast.(however, domain of value cannot be large, e.g. SEX(m,f); degree(BS,MS,PHD) 

Hash: A hashing algorithm is used to assign a set of characters to represent a text string such as a composite of keys or partial keys, and compresses the underlying data. Takes longer to build and is supported by relatively few databases.

Other Important Topics in SQL:
  1. What Is SYNONYMS In SQL
  2. What Is Translate Function?
  3. What is Materialized View in SQL?
  4. What is UNION And UNION ALL
  5. What is the difference between IN and EXISTS in Subqueries?
  6. What is the difference between Truncate and Delete Commands
  7. What is the use of Cascade Constraint?

COMMENTS

BLOGGER: 2
Loading...
Name

Advance Table In OAF,1,AOL Concepts,18,AP Holds,1,Apps Initialization,1,Blanket Purchase Orders,1,Blanket Releases,1,Careers,9,Common Errors and Solutions,2,Concurrent Programs,10,Contract Purchase Orders,1,Corporate Culture,3,Corporate Ladder,3,Customer Interface,3,Customization,1,De-Normalization,1,EAM,1,EBS Tutorials,10,Education,16,Emterprise Asset Management,1,English,1,Enterprise Asset Management,1,Entrepreneur,1,Error Fixes,1,Executables,2,Extension,1,fnd_user,1,FNDLOAD,1,Global Agreements,1,Guest Posts,7,Handy Scripts,63,Health Tips,1,Important Apps Queries,1,Infographic,3,Interview Preparation,57,Interview Q/A,57,Inventory Org ID,1,Iproc,4,Iprocurement,4,IT,3,jDeveloper,1,Job Search,1,Key Tables In Oracle Apps,5,Learning English,1,MDS,1,Metadata Tables,2,Multi Org Architecture,2,Normalization,1,O2C,1,OAF Interview,49,OAF Personalization,1,OAF Tutorials,52,Operating Unit,1,Oracle Alerts,1,Oracle AP,11,Oracle APIs,4,Oracle Application Object Library,19,Oracle Applications,10,Oracle Apps,2,Oracle Apps Interviews,29,Oracle Apps Tips,8,Oracle Apps Tutorials,97,Oracle AR,18,Oracle Assets,2,Oracle Dabase Structure,2,Oracle Database Architecture,2,Oracle Database Key Tables,3,Oracle EAM,2,Oracle EBS,5,Oracle Financials,2,Oracle Forms And Reports,17,Oracle Forms Interview Questions,6,Oracle Forms Tutorials,6,Oracle GL,4,Oracle Holds,1,Oracle HRMS,10,Oracle Human Resources,1,Oracle Inventory,4,Oracle Payables,1,Oracle Payroll,1,Oracle POTutorials,1,Oracle Purchasing,7,Oracle Reports Interview,9,Oracle Reports Tutorials,3,Oracle System Administrator,4,Oracle Workflow,3,Order Management,2,Organization ID,3,Organizations,3,Performance Tuning,2,Personalization,1,PL/SQL Block,1,PL/SQL Interview Questions,11,PL/SQL Scripts,44,PL/SQL Tutorials,53,Planned Purchase Orders,1,PO,1,PO Action History,1,PO_ACTION_HISTORY,1,POracle Purchasing,1,PR,1,Procedures And Functions,2,Profile Options,2,Purchase Orders,1,Purchase Requisition,2,Receipts,1,Request Groups,1,Responsibility,1,Shell Script,1,SOA Tutorials,4,Social Media,1,Software Industry,2,Software Tools,1,SQL And PL/SQL Interview,38,SQL Interview,51,SQL Scripts,38,SQL Tutorials,43,Standard Purchase Orders,1,Troubleshooting,1,Unexpected error,1,Unix/Linux Commands,3,User,1,Value Sets,1,Weblogic,1,XML Publisher,3,
ltr
item
Oracle Apps Guy: What Is An INDEX & What are Types of INDEX | SQL Tutorials
What Is An INDEX & What are Types of INDEX | SQL Tutorials
Oracle Apps Guy
https://www.oracleappsguy.com/2011/04/what-is-index-what-are-types-of-index.html
https://www.oracleappsguy.com/
https://www.oracleappsguy.com/
https://www.oracleappsguy.com/2011/04/what-is-index-what-are-types-of-index.html
true
4186973960539901882
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS CONTENT IS PREMIUM Please share to unlock Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy