There are many index types within Oracle:

B*Tree Indexes - common indexes in Oracle. They are similar construct to a binary tree, they provide fast access by KEY, to an individual row or range of rows, normally requiring very few reads to find the correct row.

The B*Tree index has several subtypes:

• Index Organised Tables - A table stored in a B*Tree structure
• B*Tree Cluster Indexes - They are used to index the cluster keys
• Reverse Key Indexes - The bytes in the key are reversed. This is used to stop sequential keys being on the same block like 999001, 999002, 999003 would be reversed to 100999, 200999, 300999 thus these would be located on different blocks.
• Descending Indexes - They allow data to be sorted from big to SMALL (descending) instead of small to big (ascending).

Bitmap Indexes - With a bitmap index , a single index entry uses a bitmap to point to many rows SIMULTANEOUSLY, they are used with low data that is mostly read-only. Schould be avoided in OLTP systems.

Function Based Indexes - These are B*Tree or bitmap indexes that store the computed result of a function on a row(s) (for example sorted results)- not the column data itself.

Application Domain Indexes - These are indexes you build and store yuorself, either in Oracle or outside of Oracle interMedia Text Indexes - This is a specialised index built into Oracle to allow for keyword searching of large bodies of text.

There are many index types within Oracle:

B*Tree Indexes - common indexes in Oracle. They are similar construct to a binary tree, they provide fast access by key, to an individual row or range of rows, normally requiring very few reads to find the correct row.

The B*Tree index has several subtypes:

Bitmap Indexes - With a bitmap index , a single index entry uses a bitmap to point to many rows simultaneously, they are used with low data that is mostly read-only. Schould be avoided in OLTP systems.

Function Based Indexes - These are B*Tree or bitmap indexes that store the computed result of a function on a row(s) (for example sorted results)- not the column data itself.

Application Domain Indexes - These are indexes you build and store yuorself, either in Oracle or outside of Oracle interMedia Text Indexes - This is a specialised index built into Oracle to allow for keyword searching of large bodies of text.