What is the difference between a clustered and a non-clustered index?

Clustered Index

• Only one per table
• Faster to read than non clustered as data is physically stored in index order

Non Clustered Index

• Can be used many times per table
• Quicker for insert and update operations than a clustered index

The leaf nodes of a clustered index contain the data pages. A non-clustered index is a special type of index in which the logical order of the index does not match the physical stored order of the rows on disk. The leaf node of a non-clustered index does not consist of the data pages.

Clustered Index is a special type of index that reorders the way records in the table are physically stored.Therefore can only have one clustered index.

Non-clustered index in which the logical order of the index does not match the physical stored order of the row in the disk.

A clustered index determines the physical order of data in a table for this Reason a table can have only one clustered index.Primary key constraint creates clustered indexes automatically if no clustered index exists on the table.

A non-clustered index is analogues to an index in a text book. The data is stored in one place, the index in another place. The index will have pointers to the storage location data. A table can have more than one non-clustered index.

CLUSTER INDEX HAVE NO SEPRATE PLACE  REQUIRE TO SAVE A TABLE

BUT NON CLUSTER INDEX HAVE REQURIE SEPERATE PLACE TO SAVE A TABLE

one table can only have one clustered index.

one table can have many non-clusterd index.

A clustered index requires no seperate storage than the table storage, anon-clusterd index requires seperate storage than the table storage to store the index information.

A clustered index actually describes the order in which records are physically stored on the disk, hence the reason you can only have one. A Non-Clustered Index defines a logical order that does not match the physical order on disk. A clustered index is essentially a sorted copy of the data in the indexed columns.

Clustered Index

• Only one per table (Promary Key)
• Clustered indexes physically order the data on the disk
• Accessing data using a clustered index is fastest.

Non Clustered Index

• Can be used many times per table

A clustered index actually describes the order in which records are physically stored on the disk, hence the reason you can only have one. A Non-Clustered Index defines a logical order that does not match the physical order on disk

Index is special look-up table that database uses to speed up data retrieval. We have2 types of index > Clustered and non-clustered index.

clustered index - 

1). Can have only one clustered index on a table.

2). Doesn't allow null values.

3). Exists on physical level.

4). Assigned for primary keys.

5). Requires no separate storage than table storage.

Non-clustered index - 

1). We can have many clustered index (~).

2). allows null value.

3). Exists on logical level.

4). Assigned for unique keys.

5). Requires separate storage than table storage to store the index information.

clustered index - Primary key to database. It can only be used 1 per table

non-clustered index - similarly to a foreign key. you can use it in multiple times in a multiple  table

A clustered index actually describes the order in which records are physically stored on the disk

A Non-Clustered Index defines a logical order that does not match the physical order on disk.