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# 示例：使用自定义参数组将主要版本从 1.1.1.0 升级到 1.2.0.2
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找到要升级的 `DBCluster`，以及用于创建数据库集群的模板。例如：

```
Description: Base Template to create Neptune Stack with Engine Version 1.1.1.0 using custom Parameter Groups 
Parameters:
  DbInstanceType:
    Description: Neptune DB instance type
    Type: String
    Default: db.r5.large
Resources:
  NeptuneDBClusterParameterGroup:
    Type: 'AWS::Neptune::DBClusterParameterGroup'
    Properties:
      Name: engineupgradetestcpg
      Family: neptune1
      Description: 'NeptuneDBClusterParameterGroup with family neptune1'
      Parameters:
        neptune_enable_audit_log: 0
  NeptuneDBParameterGroup:
    Type: 'AWS::Neptune::DBParameterGroup'
    Properties:
      Name: engineupgradetestpg
      Family: neptune1
      Description: 'NeptuneDBParameterGroup1 with family neptune1'
      Parameters:
        neptune_query_timeout: 20000
  NeptuneDBCluster:
    Type: 'AWS::Neptune::DBCluster'
    Properties:
      EngineVersion: 1.1.1.0
      DBClusterParameterGroupName:
        Ref: NeptuneDBClusterParameterGroup
    DependsOn:
      - NeptuneDBClusterParameterGroup
  NeptuneDBInstance:
    Type: 'AWS::Neptune::DBInstance'
    Properties:
      DBClusterIdentifier:
        Ref: NeptuneDBCluster
      DBInstanceClass:
        Ref: DbInstanceType
      DBParameterGroupName:
        Ref: NeptuneDBParameterGroup
    DependsOn:
      - NeptuneDBCluster
      - NeptuneDBParameterGroup
Outputs:
  DBClusterId:
    Description: Neptune Cluster Identifier
    Value:
      Ref: NeptuneDBCluster
```
+ 将自定义 `DBClusterParameterGroup` 系列更新为新引擎版本（此处为 `default.neptune1.2`）使用的系列。
+ 对于附加到 `DBCluster` 的每个 `DBInstance`，请将自定义 `DBParameterGroup` 系列更新为新引擎版本（此处为 `default.neptune1.2`）所使用的系列。
+ 将 `DBInstanceParameterGroupName` 属性设置为该系列中的参数组（此处为 `default.neptune1.2`）。
+ 将 `EngineVersion` 属性从 `1.1.0.0` 更新为 `1.2.0.2`：

模板应该如下所示：

```
Description: Template to upgrade major engine version to 1.2.0.2 by modifying existing custom parameter groups
Parameters:
  DbInstanceType:
    Description: Neptune DB instance type
    Type: String
    Default: db.r5.large
Resources:
  NeptuneDBClusterParameterGroup:
    Type: 'AWS::Neptune::DBClusterParameterGroup'
    Properties:
      Name: engineupgradetestcpgnew
      Family: neptune1.2
      Description: 'NeptuneDBClusterParameterGroup with family neptune1.2'
      Parameters:
        neptune_enable_audit_log: 0
  NeptuneDBParameterGroup:
    Type: 'AWS::Neptune::DBParameterGroup'
    Properties:
      Name: engineupgradetestpgnew
      Family: neptune1.2
      Description: 'NeptuneDBParameterGroup1 with family neptune1.2'
      Parameters:
        neptune_query_timeout: 20000
  NeptuneDBCluster:
    Type: 'AWS::Neptune::DBCluster'
    Properties:
      EngineVersion: 1.2.0.2
      DBClusterParameterGroupName:
        Ref: NeptuneDBClusterParameterGroup
      DBInstanceParameterGroupName:
        Ref: NeptuneDBParameterGroup
    DependsOn:
      - NeptuneDBClusterParameterGroup
  NeptuneDBInstance:
    Type: 'AWS::Neptune::DBInstance'
    Properties:
      DBClusterIdentifier:
        Ref: NeptuneDBCluster
      DBInstanceClass:
        Ref: DbInstanceType
      DBParameterGroupName:
        Ref: NeptuneDBParameterGroup
    DependsOn:
      - NeptuneDBCluster
      - NeptuneDBParameterGroup
Outputs:
  DBClusterId:
    Description: Neptune Cluster Identifier
    Value:
      Ref: NeptuneDBCluster
```

现在使用 CloudFormation 来运行修改后的模板。