Sql_Index

[User 11127370]

Hi, My question is that,when we can create Clustered and NonClustered Index on tables??? What is the purpose behind it??? Thanks...

[Mycroft Holmes]

The minimum research will get you this[^] reference

Never underestimate the power of human stupidity RAH

[GuyThiebaut]

A clustered index means that when you get to the end the end leaf of the index, you are at the physical location of the data you are looking for. This makes reading data very fast. None clustered indexes by contrast point to a physical location of data - this means that when you do reach the end leaf on a non-clustered index the disk head may have to move to get you your data. The one downside of a clustered index is that if you have a lot of inserts to the indexed table a clustered index will be disadvantageous. This is because every insert into the table will probably require a reorganisation of the physical location of some rows in the table that are not connected to the rows that you are inserting. The simple answer is - a clustered index is very useful when you have a lot of reading and not much writing.

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