Types of Table Indexes in SQL

[Truster]

Hi All,

I am learning SQL. I know SQL is query language which is used for the data retrieval. But I want to be aware about the types of indexes in SQL. I don't have any idea about the indexers types. I have referred many SQL book to know about the indexes types. But unfortunately didn't get proper detail. I you have knowledge about the types of SQL indexes, then please let me know that. I am waiting for your reply.

[Modifier]

Basically there are two types of indexers i.e Clustered indexes and Non-clustered indexes. A clustered index used when we want to sorts as well to hold the rows of the SQL table or SQL view in order which is based on the clustered index key. The clustered index is basically applied as a B-tree index structure. This structure has support to the fast retrieval of the data rows, and this retrieval is related to the values of the clustered index key.

[Praetor]

Following are some possible types of indexes:

• Spatial
• Index with included columns
• Nonclustered
• Indexed views
• Clustered
• Filtered
• Full-text

[Katty]

Hi friend,

The indexes of SQL is divided into Clustered and Non-Clustered indexes. If you want to retrieve from the clustered index then you need following:

1. Single read for intermediate level
2. Single read for index root level.
3. Single read for data page.

[kelfro]

According to my SQL knowledge there are two types of indexes, one i Clustered and another is nonclustered. There are some differences in among these two type of indexes. Below I have mentioned some differences:
* The leaf level in nonclustered indexes hold one key-pointer pair for the each row in the table.
* The leaf pages from nonclustered indexes aren't the same as the data pages.
* The intermediate index level and root of nonclustered indexes hold index keys as well as the page pointers to the other pages of index.