Partitioned Indexes

Figure 11–7 Global Partitioned Index

Partitioned

Indexes

Partitioned

Tables

Global Nonpartitioned Indexes

Global nonpartitioned indexes behave just like a nonpartitioned index. They are commonly used in OLTP environments and offer efficient access to any individual record.

Figure 11–8 offers a graphical view of global nonpartitioned indexes.

Partitioned Tables and Indexes 11-17

Partitioned Indexes

Figure 11–8 Global Nonpartitioned Index

Index

Partitioned

Tables

Partitioned Index Examples

Example of Index Creation: Starting Table Used for Examples

CREATE TABLE employees (employee_id NUMBER(4) NOT NULL, last_name VARCHAR2(10), department_id NUMBER(2)) PARTITION BY RANGE (department_id)

(PARTITION employees_part1 VALUES LESS THAN (11) TABLESPACE part1, PARTITION employees_part2 VALUES LESS THAN (21) TABLESPACE part2, PARTITION employees_part3 VALUES LESS THAN (31) TABLESPACE part3);

Example of a Local Index Creation

CREATE INDEX employees_local_idx ON employees (employee_id) LOCAL;

Example of a Global Index Creation

CREATE INDEX employees_global_idx ON employees(employee_id);

Example of a Global Partitioned Index Creation

CREATE INDEX employees_global_part_idx ON employees(employee_id) GLOBAL PARTITION BY RANGE(employee_id)

(PARTITION p1 VALUES LESS THAN(5000), PARTITION p2 VALUES LESS THAN(MAXVALUE));

11-18 Oracle9i Database Concepts

Partitioned Indexes

Example of a Partitioned Index-Organized Table Creation

CREATE TABLE sales_range

(

salesman_id NUMBER(5), salesman_name VARCHAR2(30), sales_amount NUMBER(10), sales_date DATE,

PRIMARY KEY(sales_date, salesman_id)) ORGANIZATION INDEX INCLUDING salesman_id OVERFLOW TABLESPACE tabsp_overflow PARTITION BY RANGE(sales_date)

(PARTITION sales_jan2000 VALUES LESS THAN(TO_DATE('02/01/2000','DD/MM/YYYY')) OVERFLOW TABLESPACE p1_overflow,

PARTITION sales_feb2000 VALUES LESS THAN(TO_DATE('03/01/2000','DD/MM/YYYY')) OVERFLOW TABLESPACE p2_overflow,

PARTITION sales_mar2000 VALUES LESS THAN(TO_DATE('04/01/2000','DD/MM/YYYY')) OVERFLOW TABLESPACE p3_overflow,

PARTITION sales_apr2000 VALUES LESS THAN(TO_DATE('05/01/2000','DD/MM/YYYY')) OVERFLOW TABLESPACE p4_overflow);

Miscellaneous Information about Creating Indexes on Partitioned Tables

You can create bitmap indexes on partitioned tables, with the restriction that the bitmap indexes must be local to the partitioned table. They cannot be global indexes.

Global indexes can be unique. Local indexes can only be unique if the partitioning key is a part of the index key.

Using Partitioned Indexes in OLTP Applications

Here are a few guidelines for OLTP applications:

Global indexes and unique, local indexes provide better performance than nonunique local indexes because they minimize the number of index partition probes.

Local indexes offer better availability when there are partition or subpartition maintenance operations on the table.

Using Partitioned Indexes in Data Warehousing and DSS Applications

Here are a few guidelines for data warehousing and DSS applications:

Partitioned Tables and Indexes 11-19