The most important step in creating a cluster is deciding which table or tables to cluster, and how. Although a clustered table can deliver a terrific performance improvement in the right circumstances, a poorly chosen cluster can decrease performance.
Once you have properly selected the table or tables you wish to cluster, you must go through a three-step process to create this database structure.
Create the cluster
The following Tooltip illustrates how to create a cluster using SQL:
Once you create a cluster, you then create the table or tables that the cluster will contain.
The syntax for creating tables that are a part of a cluster is exactly the same syntax that is used for non-clustered tables, with one exception. The final clause in the CREATE TABLE statement is:
CLUSTER cluster_name (column_name)
The cluster_name is the same name that was given to the cluster in the CREATE CLUSTER command.
The column_name is a list of columns in the table being created that match up with the columns in the already created cluster.
Create the cluster key
The final step is to create a cluster index. You will learn to do this in Lesson 5 of this module.
The following simplified code is an example of creating a cluster and the tables it will contain: