Parallel Query Configuration
by Brian Laskey, David C. Kreines
Oracle Database Administration: The Essential Refe
- Dedication
- Preface
- I. DBA Tasks
- 1. Introduction
- 2. Installation
- 3. Maximizing Oracle Performance
- 4. Preventing Data Loss
- 5. Oracle Networking
- Oracle Names
- MultiProtocol Interchange
- Connecting to Non-Oracle Databases
- Network Manager Data Storage
- Using Network Manager
- Files Created by Network Manager
- Oracle Net8 Assistant
- Manual Network Configuration
- Sample SQL*Net Files
- SQL*Net Troubleshooting
- 6. Security and Monitoring
- 7. Auditing
- 8. Query Optimization
- 9. Oracle Tools
- 10. The Oracle Instance
- 11. The Oracle Database
- 12. Initialization Parameters
- 13. SQL Statements for the DBA
- SQL Commands by Task
- SQL Command Syntax
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- Reference Section
- column_constraint_clause
- auto_extend_clause
- for_clause
- filespec
- autoextend_clause
- global_index_clause
- local_index_clause
- table_constraint_clause
- table_ref_clause
- column_ref_clause
- column_constraint_clause
- index_organization_clause
- segment_attrib_clause
- partition_clause
- autoextend_clause
- 14. The Oracle Data Dictionary
- Static Data Dictionary Views
- Dynamic Performance Data Dictionary Views
- 15. System Privileges and Initial Roles
- 16. Tools and Utilities
Parallel Query Configuration
Parallel Query Option (PQO) is a powerful feature of Oracle, but in order to use it properly, the database must be configured properly. Parallel Query allows multiple CPU systems to divide certain database tasks (usually full table scans) into several pieces that can be executed at the same time (in parallel). In order to perform this task, the following are required:
Multiple parallel processes must be permitted by setting the INIT.ORA parameter PARALLEL_MAX_SERVERS to a value greater than 0.
Tablespaces must be created using multiple datafiles, which should be allocated to separate devices. Ideally, there will be as many devices allocated to each tablespace as there are CPUs in the system.
Tables taking advantage of Parallel Query should have their degree of parallelism set (using the PARALLEL clause in the CREATE TABLE statement) to the number of datafiles comprising the tablespace in which the table is created.
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