PolarDB is a next-generation relational database service developed by Alibaba Cloud. Cloud-native database uses a compute-storage separation architecture and integrates software with hardware. This way, PolarDB can provide users with extremely flexible, high-performance, secure, and reliable database services that allow you to store large amounts of data. PolarDB is fully compatible with MySQL 5.6, MySQL 5.7, MySQL 8.0, and PostgreSQL 11, and is highly compatible with Oracle.
PolarDB uses an architecture in which computing is decoupled from storage. All compute nodes share the same physical storage. PolarDB allows you to upgrade or downgrade instance specifications within minutes and perform failovers within seconds. PolarDB ensures global data consistency. It also provides data backup and disaster recovery services free of charge. PolarDB has the following benefits of commercial databases: stability, reliability, high performance, and scalability. It also has the following benefits of open source cloud databases: ease of use, high compatibility, and self-iteration. For example, the performance of PolarDB for MySQL can be up to six times that of MySQL. However, the cost of an PolarDB for MySQL database is only 10% that of a commercial database. PolarDB for MySQL is fully compatible with open source MySQL and ApsaraDB RDS for MySQL. You can migrate data from MySQL to PolarDB for MySQL without modifying the code or configurations of your application.
- Computing and storage are decoupled. A distributed storage system is shared by all
PolarDB decouples computing from storage. This way, you can use auto scaling to meet the dynamic requirements of your business. All compute nodes share the same underlying physical storage PolarStore by using the distributed file system PolarFileSystem. This significantly reduces your storage costs.
- Each cluster consists of one primary node and multiple read-only nodes. This allows
PolarDB to provide read/write splitting.
PolarDB Cluster Edition uses multi-node clusters to provide services. Each PolarDB cluster consists of one primary node and at least one read-only node. You can perform read and write operations on the primary node. PolarDB uses PolarProxy to provide external services for the applications that are connected to cluster endpoints. PolarProxy forwards the requests from the applications to database nodes. You can use PolarProxy to implement authentication, data protection, and automatic read/write splitting. PolarProxy parses SQL statements, and then sends write requests to the primary node and distributes read requests to read-only nodes for load balancing. PolarProxy allows applications to access PolarDB by using the same method that is used to access a single-node database.
- Large storage capacity
Each cluster provides a maximum storage capacity of 100 TB. You do not need to purchase instances for database sharding due to the storage limit of a single host. This simplifies the development of applications and reduces the O&M workloads.
- Shared storage: PolarDB decouples computing from storage. Each time you add read-only nodes to a PolarDB cluster, you are charged only for the computing resources. However, in a traditional database solution, you are charged for both computing and storage resources.
- Elastic storage: You do not need to specify the storage capacity. The storage capacity is automatically scaled based on the data volume. You are charged on an hourly basis only for the storage that you use.
- Storage plan: PolarDB provides subscription storage plans. If you need to store a large amount of data, we recommend that you purchase storage plans. Storage plans are more cost-effective than the pay-as-you-go billing method. You are offered higher discounts for storage plans that have larger storage capacities.
- High performance
PolarDB significantly improves online transaction processing (OLTP) performance and supports more than 500,000 read requests per second and more than 150,000 write requests per second.
- Elastic scaling within minutes
PolarDB supports rapid scaling for computing. This is based on container virtualization, shared distributed storage, and compute-storage separation. It requires only 5 minutes to add or remove a node. The storage capability is automatically scaled up. During the scale-up process, your services are not interrupted.
- Read consistency
PolarDB uses log sequence numbers (LSNs) for cluster endpoints that have read/write splitting enabled. This ensures global consistency for read operations and prevents the inconsistency that is caused by the replication delay between the primary node and read-only nodes.
- Millisecond-level latency in physical replication
PolarDB performs physical replication from the primary node to read-only nodes based on redo logs. The physical replication replaces the logical replication that is based on binary logs. This way, the replication efficiency and stability are improved. No delays occur even if you perform DDL operations on a large table, such as adding indexes or fields.
- Data backup within seconds
No more than 30 seconds are required to perform a full backup on a database regardless of the data volume of the database. During the backup, the database is not locked. This minimizes the impact of data backup on your applications. You can specify a point in time to back up the database data based on your business requirements.
You can use the following methods to manage PolarDB clusters. Cluster management includes creating clusters, databases, and accounts.
- Console: PolarDB provides a visualized web interface. This simplifies management operations.
- CLI: You can use Alibaba Cloud CLI to perform all the operations that are available in the console.
- SDK: You can use SDKs to perform all the operations that are available in the console.
- API: You can call API operations to perform all the operations that are available in the console.
After a PolarDB cluster is created, you can use the following methods to connect to the PolarDB cluster:
- Use Data Management (DMS) to connect to a PolarDB cluster and develop databases in the DMS console. For more information, see Use DMS to connect to an ApsaraDB PolarDB MySQL-compatible edition cluster.
- Use a common database client to connect to a PolarDB cluster. For example, you can use MySQL-Front or pgAdmin to connect to a PolarDB cluster.
Before you purchase and use PolarDB, we recommend that you familiarize yourself with the following terms:
- Cluster: PolarDB Cluster Edition uses a cluster architecture. A cluster of Overview consists of 1 primary node and a maximum of 15 read-only nodes.
- Region: A region is a geographic area where a data center is deployed. In most cases, PolarDB clusters must be deployed in the same region as Elastic Compute Service (ECS) instances to ensure optimal access performance.
- Zone: A zone is a geographic area in a region. Each zone has an independent power supply and network. All the zones in a region provide the same services.
- Specification: A specification specifies the resources that are configured for each node, such as 2 CPU cores and 8 GB memory.
- ECS: ECS instances serve as cloud servers. If you connect to a PolarDB cluster from an ECS instance that is deployed in the same region as the PolarDB cluster over an internal network, the PolarDB cluster provides optimal performance. In a typical service architecture, ECS instances are used in combination with PolarDB clusters.
- ApsaraDB for Redis: ApsaraDB for Redis is a database service that supports in-memory storage and persistent storage. In scenarios in which large numbers of access requests exist, you can use ECS, PolarDB, and ApsaraDB for Redis to improve the read IOPS and reduce the response time.
- ApsaraDB for MongoDB: ApsaraDB for MongoDB is a stable, reliable, and scalable database service that is fully compatible with MongoDB protocols. To meet various business requirements, you can store structured data in PolarDB and unstructured data in ApsaraDB for MongoDB.
- Data Transmission Service (DTS): You can use DTS to migrate on-premises databases to PolarDB clusters.
- Object Storage Service (OSS): OSS is a secure, cost-effective, and reliable cloud storage service that allows you to store large amounts of data.