Ten Best Things About Indexing

To day I wanna share all that I know about indexing for beginners.

1. An index is a performance-tuning method of allowing faster retrieval of records.

2. It's easy and provides immediate value, because it's just a CREATE INDEX statement

3.It can be used to speed up existing applications without changing any of their logic or queries

4. It can be used to supply additional functionality to applications with very little cost

5. An index creates an entry for each value that appears in the indexed columns. By default, Oracle creates B-tree indexes.

6.Because I/Os are expensive operations on a computer system, table scans are very expensive. Reducing the amount of data that is read from the disk is desirable. By reducing the amount of data that is read, you reduce system overhead. An index improves your performance by knowing exactly where the data is on disk and avoiding costly table scans, thus reducing I/O overhead.

6. Indexes are transparent to the end-user application.

7.Oracle automatically maintains the indexes during a DML operation on the table. Oracle Optimizer chooses the suitable index during a SQL SELECT operation.

8.Oracle manages the index for you, there are no additional commands you need to use to keep the index sync'd with the table.

9. It can allow the SQL optimizer to avoid large chunks of data blocks and narrow down the candidate blocks very quickly taking a query that takes minutes to run to less than a second to run.

10. an index is one of the best features of an RDBMS and will solve so many of your performance and scalability issues