Oracle provides a clustering technique that can be very useful for an aggregation relationship. : Cluster « Table « Oracle PL / SQL






  1. Oracle PL / SQL
  2. Table
  3. Cluster

Oracle provides a clustering technique that can be very useful for an aggregation relationship.

   
SQL> --General Syntax:
SQL>
SQL> --CREATE CLUSTER <cluster schema>
SQL> --   (cluster attribute            attribute type);
SQL>
SQL> --CREATE TABLE <table schema>
SQL> --   (cluster attribute      attribute type,
SQL> --    attribute              attribute type, ....,
SQL> --    attribute              attribute type)
SQL> --   CLUSTER <cluster schema> (cluster attribute);
SQL>
SQL> --CREATE INDEX <index schema> ON CLUSTER <cluster schema>;
SQL>
SQL> --Example:
SQL>
SQL> CREATE CLUSTER Part_Cluster
  2      (hd_id            VARCHAR2(10));

Cluster created.

SQL>
SQL>
SQL>
SQL> CREATE TABLE Hard_Disk
  2      (hd_id            VARCHAR2(10) NOT NULL,
  3       capacity         VARCHAR2(20),
  4       PRIMARY KEY (hd_id))
  5      CLUSTER Part_Cluster(hd_id);

Table created.

SQL>
SQL>
SQL>
SQL>
SQL> CREATE INDEX Part_Cluster_Index
  2      ON CLUSTER Part_Cluster;

Index created.

SQL>
SQL>
SQL>
SQL> drop table Hard_Disk;

Table dropped.

SQL>
SQL>
SQL>
SQL> drop CLUSTER Part_Cluster ;

Cluster dropped.
SQL>








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