应用补丁

Oracle

# 1) Shut down the database, apply the binary patch with OPatch:
$ $ORACLE_HOME/OPatch/opatch apply
# 2) Open the database and load the SQL layer changes:
$ $ORACLE_HOME/OPatch/datapatch -verbose

opatch apply 更新 Oracle Home 中的二进制文件；随后 datapatch 在打开的数据库上应用数据字典/SQL 变更，并记录到 dba_registry_sqlpatch 中。在 RAC 上，支持滚动安装的补丁可逐节点应用。

PostgreSQL

# Minor version patch = replace binaries + restart (no dump needed):
$ sudo systemctl stop postgresql-16
$ sudo dnf update postgresql16-server   # or apt upgrade
$ sudo systemctl start postgresql-16

同一大版本系列内的小版本补丁（16.3 -> 16.4）不会改变数据格式：更新软件包并重启服务即可；无需 pg_upgrade 或 dump/restore。

MySQL

# Minor/patch update: update the package and restart the service
$ sudo systemctl stop mysqld
$ sudo dnf update mysql-community-server   # or apt upgrade
$ sudo systemctl start mysqld

MySQL 8.0+ 在启动时自动升级数据字典；无需单独的 mysql_upgrade 步骤。在复制环境中，先给副本打补丁，再给源库打补丁。

SQL Server

-- Run the Cumulative Update (CU) or GDR security update installer:
-- SQLServer2022-KB<no>-x64.exe /quiet /IAcceptSQLServerLicenseTerms
--   /Action=Patch /InstanceName=MSSQLSERVER
-- The instance then restarts; verify the version with SERVERPROPERTY.

CU（Cumulative Update）和 GDR（General Distribution Release）更新通过 setup 安装程序应用，需要重启实例。在 Always On 组中，先给辅助副本打补丁，再进行故障转移，以尽量缩短停机时间。

MongoDB

// 'Rolling' patch on a replica set: one node at a time
// 1) Stop mongod, replace the binary with the new patch version, restart
// 2) Secondaries first, the primary last
// Step down the primary manually before patching it:
rs.stepDown()

同一大版本内的补丁更新（7.0.x）以滚动方式进行，先从节点。主节点在通过 rs.stepDown() 移交后再打补丁，从而尽量缩短写入停机时间。

Redis

# Patch via rolling restart in a replicated deployment:
# 1) Stop one replica node, install the new version, start it, wait for sync
# 2) Repeat for the remaining replicas
# 3) Finally, fail over the master and patch it:
redis-cli -h <replica> REPLICAOF NO ONE   # promote the upgraded replica

补丁版本（7.2.x）通过滚动重启应用：先升级副本并重新同步，然后将一个副本提升为 master，再给旧 master 打补丁。Sentinel/Cluster 可自动完成故障转移。

Elasticsearch

# Rolling upgrade (patch within the same major version), per node:
PUT _cluster/settings
{ "persistent": { "cluster.routing.allocation.enable": "primaries" } }
# -> stop the node, update the package, start the node, then:
PUT _cluster/settings
{ "persistent": { "cluster.routing.allocation.enable": null } }

补丁/小版本升级通过滚动升级完成：限制分片分配，逐个更新并重启节点，然后重新启用分配，等待集群恢复为 green。