Clustered vs Non-clustered indexes

Clustered Index

Primary Key anlamına gelir gibi düşünülebilir. Açıklaması şöyle.  

Clustered and non-clustered indexes

The primary key index is also a clustered index, and the non-primary key index is non-clustered. 

Non-Clustered Index

CREATE INDEX ile yaratılır. Açıklaması şöyle.  

Secondary indexes are always unclustered, ie you can’t find the full row by simply searching on a secondary key value, you only get the primary key which uniquely identifies the row which you then need to scan the primary key index to find the full row. This is how MySQL is structured by default.