要查询S3存储桶中目录的大小，可以使用Athena查询语言结合S3 Select功能来实现。以下是一个使用Python和boto3库的示例代码：

import boto3

# 创建Athena客户端
athena = boto3.client('athena')

# 定义查询语句
query = """
    SELECT SUM(size_bytes) AS directory_size
    FROM "s3object"
    WHERE s3_object_path LIKE 's3://your-bucket-name/your-folder-path/%'
"""

# 执行查询
response = athena.start_query_execution(
    QueryString=query,
    ResultConfiguration={
        'OutputLocation': 's3://your-bucket-name/athena-results'
    }
)

# 获取查询执行ID
query_execution_id = response['QueryExecutionId']

# 等待查询执行完成
response = athena.get_query_execution(
    QueryExecutionId=query_execution_id
)

status = response['QueryExecution']['Status']['State']
while status == 'RUNNING':
    response = athena.get_query_execution(
        QueryExecutionId=query_execution_id
    )
    status = response['QueryExecution']['Status']['State']

# 获取查询结果
response = athena.get_query_results(
    QueryExecutionId=query_execution_id
)

# 解析查询结果
result = response['ResultSet']['Rows'][1]['Data'][0]['VarCharValue']
directory_size = int(result)

print("The directory size is: ", directory_size)

请确保您已经安装了boto3库，并替换示例代码中的“your-bucket-name”和“your-folder-path”为您要查询的S3存储桶名称和目录路径。此示例将打印出目录的大小。