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# 第 8 步（可选）：清除资源
<a name="getting-started.python.step-8"></a>

**重要**  
终止支持通知：现有客户将能够使用 Amazon QLDB，直到 2025 年 7 月 31 日终止支持。有关更多详细信息，请参阅[将亚马逊 QLDB 账本迁移到亚马逊 Aurora PostgreSQL](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)。

您可以继续使用 `vehicle-registration` 分类账。但是，如果您不再需要，请将其删除。

**删除分类账**

1. 使用以下程序（`delete_ledger.py`）以删除您的 `vehicle-registration` 分类账及其所有内容。

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   from time import sleep
   
   from boto3 import client
   
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.describe_ledger import describe_ledger
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   qldb_client = client('qldb')
   
   LEDGER_DELETION_POLL_PERIOD_SEC = 20
   
   
   def delete_ledger(ledger_name):
       """
       Send a request to QLDB to delete the specified ledger.
   
       :type ledger_name: str
       :param ledger_name: Name for the ledger to be deleted.
   
       :rtype: dict
       :return: Result from the request.
       """
       logger.info('Attempting to delete the ledger with name: {}...'.format(ledger_name))
       result = qldb_client.delete_ledger(Name=ledger_name)
       logger.info('Success.')
       return result
   
   
   def wait_for_deleted(ledger_name):
       """
       Wait for the ledger to be deleted.
   
       :type ledger_name: str
       :param ledger_name: The ledger to check on.
       """
       logger.info('Waiting for the ledger to be deleted...')
       while True:
           try:
               describe_ledger(ledger_name)
               logger.info('The ledger is still being deleted. Please wait...')
               sleep(LEDGER_DELETION_POLL_PERIOD_SEC)
           except qldb_client.exceptions.ResourceNotFoundException:
               logger.info('Success. The ledger is deleted.')
               break
   
   
   def set_deletion_protection(ledger_name, deletion_protection):
       """
       Update an existing ledger's deletion protection.
   
       :type ledger_name: str
       :param ledger_name: Name of the ledger to update.
   
       :type deletion_protection: bool
       :param deletion_protection: Enable or disable the deletion protection.
   
       :rtype: dict
       :return: Result from the request.
       """
       logger.info("Let's set deletion protection to {} for the ledger with name {}.".format(deletion_protection,
                                                                                             ledger_name))
       result = qldb_client.update_ledger(Name=ledger_name, DeletionProtection=deletion_protection)
       logger.info('Success. Ledger updated: {}'.format(result))
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Delete a ledger.
       """
       try:
           set_deletion_protection(ledger_name, False)
           delete_ledger(ledger_name)
           wait_for_deleted(ledger_name)
       except Exception as e:
           logger.exception('Unable to delete the ledger.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```
**注意**  
如果分类账启用了删除保护，您必须先禁用它，然后才能使用 QLDB API 删除分类账。

   `delete_ledger.py` 文件还依赖于以下程序（`describe_ledger.py`）。

   ```
   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from boto3 import client
   
   from pyqldbsamples.constants import Constants
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   qldb_client = client('qldb')
   
   
   def describe_ledger(ledger_name):
       """
       Describe a ledger.
   
       :type ledger_name: str
       :param ledger_name: Name of the ledger to describe.
       """
       logger.info('describe ledger with name: {}.'.format(ledger_name))
       result = qldb_client.describe_ledger(Name=ledger_name)
       result.pop('ResponseMetadata')
       logger.info('Success. Ledger description: {}.'.format(result))
       return result
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Describe a QLDB ledger.
       """
       try:
           describe_ledger(ledger_name)
       except Exception as e:
           logger.exception('Unable to describe a ledger.')
           raise e
   
   
   if __name__ == '__main__':
       main()
   ```

1. 要运行该程序，请输入以下命令。

   ```
   python delete_ledger.py
   ```