Version upgrades for PolarDB for PostgreSQL are classified as minor version upgrades and major engine version upgrades. The two types of upgrades differ significantly in content, compatibility, operation, and business impact:
Comparison item | Minor version upgrade | Major engine version upgrade |
Version number change | Only the patch version number changes. For example, an upgrade from | The major kernel version number changes. For example, an upgrade from |
Upgrade content | Primarily includes kernel bug fixes, security vulnerability patches, stability improvements, and performance optimizations. New features are usually not introduced. | Introduces new features, new syntax, major architectural improvements, or behavior changes, such as changes to the index format, Write-Ahead Logging (WAL) format, or system views. |
Compatibility | Fully backward compatible. Applications can run normally without any modifications. | May include incompatible changes. Before you upgrade, you must conduct thorough compatibility tests on your applications. For example, test SQL behavior, extension support, and parameter settings. |
Upgrade method | The upgrade is performed using an online rolling upgrade. This process typically involves only a transient disconnection that lasts for a few seconds and does not require data migration. | Requires data migration using a service such as DTS. The operation is complex and time-consuming. |
Trigger Methods | You can typically trigger the upgrade manually. To address important security vulnerabilities, the system may also initiate a mandatory upgrade within the maintenance window that you set. | These upgrades are not triggered automatically. You must plan, initiate, and fully validate the upgrade. |
Rollback capability | Supports fast rollback. | Rollback is supported. However, a manual switchover to the original cluster is required. |