PolarDB is a new-generation relational database service that is developed by Alibaba Group. This service decouples computing from storage and uses integrated software and hardware. PolarDB is a secure and reliable database service that provides auto scaling, high performance, and mass storage. PolarDB is fully compatible with PostgreSQL 11, PostgreSQL 14. PolarDB is highly compatible with Oracle.
PolarDB uses an architecture that decouples computing from storage. Data of a cluster is shared across all compute nodes. PolarDB allows you to upgrade or downgrade specifications within minutes, and supports disaster recovery within seconds. PolarDB ensures global data consistency and offers data backup and disaster recovery for free. PolarDB has the benefits of both commercial databases and open source cloud databases. Commercial databases are stable, scalable, and high-performance. Open source cloud databases are easy to use and feature rapid iteration
PolarDB uses a compute-storage decoupled architecture and a distributed storage system. Data is shared across all compute nodes.
PolarDB decouples computing and storage, which delivers flexibility and scalability to meet your business requirements. All compute nodes share the same data by using a distributed file system. This significantly reduces storage costs.
Each cluster consists of one primary node and at least one read-only node. This allows PolarDB to provide read/write splitting.
PolarDB uses multi-node clusters to provide services. Each PolarDB cluster consists of one primary node that handles both read and write operations and at least one read-only node. PolarDB uses PolarProxy to provide services for external applications that are connected through the cluster endpoints. PolarProxy forwards the requests from the applications to database nodes. The proxy can perform authentication and help ensure data security. It implements automatic read/write splitting by parsing SQL statements, sending write requests to the primary node, and evenly distributing read requests across read-only nodes. The proxy allows applications to access PolarDB by using the same method that is used to access a single-node database.
Benefits
You can use PolarDB in the same way that you use PostgreSQL, or Oracle. Compared with traditional databases, PolarDB has the following advantages:
Large storage capacity
The maximum storage capacity of a cluster is 500 TB. You do not need to purchase instances for database sharding due to the storage limit of a single host. This simplifies application development and reduces the O&M workload.
Cost-effectiveness
Shared storage: PolarDB decouples computing and storage. When you add read-only nodes to a PolarDB cluster, you are charged only for the computing resources of these nodes. In traditional database solutions, you are charged for both computing and storage resources when you add read-only nodes.
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 plans: PolarDB provides subscription storage plans. To store a large volume of data, we recommend that you purchase subscription storage plans. Storage plans are more cost-effective than pay-as-you-go storage. You are offered higher discounts for storage plans with larger storage capacities.
High performance
PolarDB 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 resources. This is based on container virtualization, shared storage, and compute-storage decoupling. It requires only 5 minutes to add or remove a node. The storage capacity 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.
Pricing
For more information, see Specifications and pricing and Purchase a PolarDB cluster.
Usage notes of PolarDB
You can manage PolarDB clusters in the following ways. For example, you can create clusters, databases, and accounts.
Console: PolarDB provides a web-based GUI. This way, you can perform operations in an efficient manner.
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 connect to the PolarDB cluster in the following ways:
DMS: You can connect to a PolarDB cluster by using Data Management (DMS) and develop databases on the DMS console. For more information, see Use DMS to connect to a PolarDB for PostgreSQL cluster.
Client: You can connect to a PolarDB cluster by using common database clients, such as pgAdmin.
Terms
Before you purchase and use PolarDB, we recommend that you learn about the following terms:
Cluster: PolarDB uses a cluster architecture. A cluster of 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 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 zones in a region provide the same services.
Specification: A specification specifies the resources on a node. For example, the specification of a node can be 2 CPU cores and 8 GB memory.
Related services
Elastic Compute Service (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 highly reliable cloud storage service that allows you to store large amounts of data in the cloud.