建立和管理非關聯式資料庫

import boto3

# Boto3 is the AWS SDK library for Python.
# You can use the low-level client to make API calls to DynamoDB.
client = boto3.client('dynamodb', region_name='us-east-1')

try:
    resp = client.update_table(
        TableName="Books",
        # Any attributes used in your new global secondary index must be declared in AttributeDefinitions
        AttributeDefinitions=[
            {
                "AttributeName": "Category",
                "AttributeType": "S"
            },
        ],
        # This is where you add, update, or delete any global secondary indexes on your table.
        GlobalSecondaryIndexUpdates=[
            {
                "Create": {
                    # You need to name your index and specifically refer to it when using it for queries.
                    "IndexName": "CategoryIndex",
                    # Like the table itself, you need to specify the key schema for an index.
                    # For a global secondary index, you can use a simple or composite key schema.
                    "KeySchema": [
                        {
                            "AttributeName": "Category",
                            "KeyType": "HASH"
                        }
                    ],
                    # You can choose to copy only specific attributes from the original item into the index.
                    # You might want to copy only a few attributes to save space.
                    "Projection": {
                        "ProjectionType": "ALL"
                    },
                    # Global secondary indexes have read and write capacity separate from the underlying table.
                    "ProvisionedThroughput": {
                        "ReadCapacityUnits": 1,
                        "WriteCapacityUnits": 1,
                    }
                }
            }
        ],
    )
    print("Secondary index added!")
except Exception as e:
    print("Error updating table:")
    print(e)

$ python add_secondary_index.py

$ python query_with_index.py

import time

import boto3
from boto3.dynamodb.conditions import Key

# Boto3 is the AWS SDK library for Python.
# The "resources" interface allows for a higher-level abstraction than the low-level client interface.
# For more details, go to http://boto3.readthedocs.io/en/latest/guide/resources.html
dynamodb = boto3.resource('dynamodb', region_name='us-east-1')
table = dynamodb.Table('Books')

# When adding a global secondary index to an existing table, you cannot query the index until it has been backfilled.
# This portion of the script waits until the index is in the “ACTIVE” status, indicating it is ready to be queried.
while True:
    if not table.global_secondary_indexes or table.global_secondary_indexes[0]['IndexStatus'] != 'ACTIVE':
        print('Waiting for index to backfill...')
        time.sleep(5)
        table.reload()
    else:
        break

# When making a Query call, you use the KeyConditionExpression parameter to specify the hash key on which you want to query.
# If you want to use a specific index, you also need to pass the IndexName in our API call.
resp = table.query(
    # Add the name of the index you want to use in your query.
    IndexName="CategoryIndex",
    KeyConditionExpression=Key('Category').eq('Suspense'),
)

print("The query returned the following items:")
for item in resp['Items']:
    print(item)

$ python query_with_index.py
The query returned the following items:
{'Title': 'The Firm', 'Formats': {'Hardcover': 'Q7QWE3U2', 'Paperback': 'ZVZAYY4F', 'Audiobook': 'DJ9KS9NM'}, 'Author': 'John Grisham', 'Category': 'Suspense'}
{'Title': 'The Rainmaker', 'Formats': {'Hardcover': 'J4SUKVGU', 'Paperback': 'D7YF4FCX'}, 'Author': 'John Grisham', 'Category': 'Suspense'}
{'Title': 'Along Came a Spider', 'Formats': {'Hardcover': 'C9NR6RJ7', 'Paperback': '37JVGDZG', 'Audiobook': '6348WX3U'}, 'Author': 'James Patterson', 'Category': 'Suspense'}