How Oracle RAC enables high availability and performance scaling

Oracle RAC (Real Application Clusters) is a high availability and performance expansion architecture of Oracle database. It can combine multiple servers into a cluster to share storage and processing capabilities, thereby improving Database system availability and performance. This article will introduce how Oracle RAC achieves high availability and performance expansion, and provide some specific code examples to help readers better understand.

1. High availability implementation of Oracle RAC

1.1 Multi-instance architecture

Oracle RAC deploys database instances on different servers so that even if one of the servers fails In the event of a failure, instances on other servers can still continue to provide services, achieving high availability. The following is a simple example showing how to create a new instance in Oracle RAC:

srvctl add instance -d <database_name> -i <instance_name> -n <node_name> -o <oracle_home>

1.2 Data Sharing

Oracle RAC uses shared storage technology, multiple instances can access database files at the same time , thereby improving system availability. The following is an example showing how to configure shared storage in Oracle RAC:

srvctl add filesystem -device <device> -path <mount_point> -diskgroup <diskgroup>

1.3 Monitoring and failover

Oracle RAC comes with Clusterware cluster management tools that can monitor each node in the cluster and The status of the instance enables rapid fault detection and transfer. The following is an example showing how to configure Clusterware for Oracle RAC:

crsctl check cluster
crsctl failover crs

2. Performance extension implementation of Oracle RAC

2.1 Load balancing

Oracle RAC can use load balancing technology Evenly distribute transaction requests to different nodes, thereby improving system performance. The following is an example showing how to configure a load balancer in Oracle RAC:

srvctl add service -d <database_name> -s <service_name> -r <preferred_instances> -a <available_instances> -P BASIC

2.2 Parallel query

Oracle RAC supports parallel queries, which can decompose a query task into multiple subtasks and execute them in Parallel execution on different instances improves query speed and efficiency. The following is an example showing how to configure parallel queries in Oracle RAC:

ALTER SESSION ENABLE PARALLEL;

2.3 Data Sharding

Oracle RAC can store data shards on different nodes, each node is responsible for Process your own data fragments, thereby improving the system's ability to handle large-scale data. The following is an example showing how to create a data sharding table in Oracle RAC:

CREATE TABLE employees
   (employee_id     NUMBER(6),
    first_name      VARCHAR2(20),
    last_name       VARCHAR2(25),
    hire_date       DATE,
    department_id   NUMBER(4))
   PARTITION BY RANGE (hire_date)
   (PARTITION employees_q1 VALUES LESS THAN (TO_DATE('01-APR-2022','DD-MON-YYYY')),
    PARTITION employees_q2 VALUES LESS THAN (TO_DATE('01-JUL-2022','DD-MON-YYYY')));

Conclusion

Through the above introduction, we understand the principles and principles of how Oracle RAC achieves high availability and performance expansion. Specific operation methods include multi-instance architecture, data sharing, load balancing, parallel query and data sharding and other technologies. It is hoped that these examples can help readers better understand and apply Oracle RAC, give full play to its advantages in practice, and improve the availability and performance of the database system.

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