Features
PolarDB-X is a distributed SQL database that combines centralized and distributed architectures in a single system. It supports hybrid transactional and analytical processing (HTAP) workloads, scales horizontally, and is fully compatible with the MySQL ecosystem in terms of SQL syntax, transaction behaviors, and ecosystem tools—letting you migrate existing MySQL workloads with minimal code changes. PolarDB-X also offers low-cost storage and infinite scalability.
Financial-grade high availability
PolarDB-X uses Paxos-based multi-replica replication to guarantee strong consistency across replicas (RPO = 0). Every write is confirmed by a majority of nodes before it succeeds, so the cluster remains available even when a node fails.
| Category | Feature | Tolerates | Description | References |
|---|---|---|---|---|
| Zone-disaster recovery | Single-zone deployment | Single-node failure | Three replicas in one zone maintain quorum when a minority node goes down. | High availability (RPO = 0) |
| Three-zone deployment | Data center failure | Three replicas spread across three zones keep the cluster running if an entire zone goes offline. | — | |
| Cross-region disaster recovery | Deployment in three data centers across two regions | Regional failure | Five replicas across two regions sustain operations if a full region becomes unavailable. | — |
Transparent distribution
PolarDB-X presents a distributed architecture that behaves like a standalone MySQL database. Underlying capabilities—distributed transaction consistency, data partitioning and scheduling, global secondary indexes (GSIs), and cross-shard queries—are handled automatically, so applications need no special handling.
PolarDB-X provides binary logging to resolve the issue of data forwarding from compute nodes to data nodes in distributed databases. In distributed databases, when nodes restore from backup files created at different points in time, data inconsistency can occur. PolarDB-X ensures data consistency before backup and creates backup files based on globally consistent data, eliminating this risk.
| Category | Feature | Description |
|---|---|---|
| Data distribution | Partitioned tables | Distributes data evenly across nodes using partition rules. |
| GSIs | Supports multi-dimensional queries across partitions in distributed databases. | |
| Manual partitioning and automatic partitioning | Provides flexible partitioning policies for migrating existing workloads with minimal effort. | |
| O&M compatibility | Global binary logs | Compatible with MySQL binary log protocol; supports incremental log subscriptions via change data capture (CDC). |
| Distributed backup and restoration | Backs up and restores distributed data consistently across all nodes. |
Integration of centralized and distributed architectures
PolarDB-X integrates centralized and distributed architectures. It provides two instance editions:
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Standard Edition — a centralized architecture optimized for single-node workloads
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Enterprise Edition — a distributed architecture for horizontal scaling
You can change between the instance editions with ease. Data nodes in PolarDB-X are isolated as centralized databases, which are fully compatible with standalone databases. The distributed components integrate seamlessly with the original data nodes, eliminating the need to migrate data or modify applications.
| Category | Feature | Description | References |
|---|---|---|---|
| Standard Edition (centralized architecture) | Paxos replicas | Majority-based consistency protocol for strong data durability. | Paxos multi-replica |
| Lizard transaction system | Alibaba Cloud's transaction system that manages commits on standalone database nodes using the System Commit Number (SCN) mechanism. | Lizard transaction system | |
| In-place upgrade | Migrate from ApsaraDB RDS for MySQL to PolarDB-X Standard Edition | Moves data from ApsaraDB RDS for MySQL to a PolarDB-X instance. | — |
| Upgrade from Standard Edition to Enterprise Edition | Upgrades the architecture to a distributed architecture from the smallest node. | Upgrade an instance from Standard Edition to Enterprise Edition |
HTAP
PolarDB-X supports hybrid transactional and analytical processing (HTAP) through clustered columnar indexes (CCIs). By default, a row-oriented table in PolarDB-X has primary key indexes and secondary indexes. A CCI is a secondary index built on a column-oriented structure and is valid for all columns in a row-oriented table. A table can contain both row-oriented data and column-oriented data. Cost-based optimizers and vectorized operators are developed for HTAP, and a set of SQL engines is used to support HTAP.
| Category | Feature | Description | References |
|---|---|---|---|
| Column-oriented data | CCIs | Provides row-oriented tables that have primary key indexes and secondary indexes by default. A CCI is a secondary index that is built on top of a column-oriented structure. | Overview |
| Cold data archiving | Archives historical data to Object Storage Service (OSS) based on time partitions. | Overview | |
| Read-only instances | Read-only column store instances | Dedicated read-only instances with link isolation that run queries on vectorized engines for analytical workloads. | Add a read-only column store instance |
Open source and multi-cloud deployment
PolarDB-X went open source in November 2021. The development team synchronizes the commercial codebase to the open source community every three to six months, keeping the community and commercial editions aligned. PolarDB-X provides lightweight management features and tools compatible with the open source ecosystem. You can use open source code to implement business production and deployment, build your own applications, and perform multi-cloud disaster recovery.
| Category | Feature | Description | References |
|---|---|---|---|
| Open source | Open source kernel engine | Includes compute nodes (CNs), data nodes (DNs), change data capture (CDC), Global Meta Service (GMS), and Columnar components. | polardbx-sql |
| Lightweight management | Kubernetes Operator-based deployment for production environments. | PolarDB-X Operator | |
| Multi-cloud deployment | Self-managed deployment on Elastic Compute Service (ECS) instances | Deploy open source PolarDB-X on physical machines or ECS instances. | Quick Start |
| Multi-cloud deployment in ApsaraDB for MyBase | Manage open source PolarDB-X deployments on ECS through a centralized database management platform. | — |
Security and stability
PolarDB-X has received multiple state-level security certifications and has been successfully applied in core systems in industries with high security requirements, such as finance and telecommunications.
| Security control | Description |
|---|---|
| IP address whitelists | Restricts database access to approved IP addresses. |
| Secure Sockets Layer (SSL) | Encrypts data in transit between clients and the database. |
| Transparent data encryption (TDE) | Encrypts data at rest without requiring application changes. |
| Backup encryption | Encrypts backup files to protect data stored off-instance. |
| Always-confidential | Keeps data encrypted during processing in memory. |
| SQL audit and tracing | Logs and traces SQL statements for compliance and forensic analysis. |
| Three-role mode | Separates database administrator, security administrator, and audit administrator duties. |
| Tag-based permissions | Controls access to resources using tag-based policies. |