使用 Amazon DynamoDB 实现高性能和可扩展性

import boto3

dynamodb = boto3.client("dynamodb")

try:
    dynamodb.create_table(
        TableName="Restaurants",
        AttributeDefinitions=[
            {"AttributeName": "PK", "AttributeType": "S"},
            {"AttributeName": "SK", "AttributeType": "S"},
            {"AttributeName": "GSI1PK", "AttributeType": "S"},
            {"AttributeName": "GSI1SK", "AttributeType": "S"},
        ],
        KeySchema=[
            {"AttributeName": "PK", "KeyType": "HASH"},
            {"AttributeName": "SK", "KeyType": "RANGE"},
        ],
        GlobalSecondaryIndexes=[
            {
                "IndexName": "GSI1",
                "KeySchema": [
                    {"AttributeName": "GSI1PK", "KeyType": "HASH"},
                    {"AttributeName": "GSI1SK", "KeyType": "RANGE"},
                ],
                "Projection": {"ProjectionType": "ALL"},
                "ProvisionedThroughput": {
                    "ReadCapacityUnits": 5,
                    "WriteCapacityUnits": 5,
                },
            }
        ],
        ProvisionedThroughput={"ReadCapacityUnits": 5, "WriteCapacityUnits": 5},
    )
    print("Table created successfully.")
except Exception as e:
    print("Could not create table. Error:")
    print(e)

import boto3

dynamodb = boto3.client("dynamodb")


def create_restaurant(name, cuisine, address):
    try:
        resp = dynamodb.put_item(
            TableName="Restaurants",
            Item={
                "PK": {"S": "REST#{}".format(name)},
                "SK": {"S": "REST#{}".format(name)},
                "GSI1PK": {"S": "REST#{}".format(name)},
                "GSI1SK": {"S": "REST#{}".format(name)},
                "name": {"S": name},
                "cuisine": {"S": cuisine},
                "address": {"S": address},
            },
            ConditionExpression="attribute_not_exists(PK)",
        )
        return {"name": name, "cuisine": cuisine, "address": address}
    except Exception as e:
        print("Could not create restaurant")
        print(e)
        return False


restaurant = create_restaurant(
    "Bev's Bistro", "French", "541 Salazar Ranch, South Kristen, MS 00857"
)

if restaurant:
    print("Created restaurant: {}".format(restaurant["name"]))

import datetime

import boto3
from ksuid import ksuid

dynamodb = boto3.client("dynamodb")

RATINGS = {
    1: "one_stars",
    2: "two_stars",
    3: "three_stars",
    4: "four_stars",
    5: "five_stars",
}


def create_review(restaurant, username, rating, review_text):
    review_id = str(ksuid())
    rating_attr = RATINGS[rating]
    try:
        resp = dynamodb.transact_write_items(
            TransactItems=[
                {
                    "Put": {
                        "TableName": "Restaurants",
                        "Item": {
                            "PK": {"S": "USER#{}".format(username)},
                            "SK": {"S": "REST#{}".format(restaurant)},
                            "GSI1PK": {"S": "REST#{}".format(restaurant)},
                            "GSI1SK": {"S": "#REVIEW#{}".format(review_id)},
                            "username": {"S": username},
                            "restaurant": {"S": restaurant},
                            "id": {"S": review_id},
                            "rating": {"N": str(rating)},
                            "review": {"S": review_text},
                            "created_at": {"S": datetime.datetime.now().isoformat()},
                        },
                        "ConditionExpression": "attribute_not_exists(PK)",
                    },
                },
                {
                    "Update": {
                        "TableName": "Restaurants",
                        "Key": {
                            "PK": {"S": "REST#{}".format(restaurant)},
                            "SK": {"S": "REST#{}".format(restaurant)},
                        },
                        "ConditionExpression": "attribute_exists(PK)",
                        "UpdateExpression": "SET #rating = if_not_exists(#rating, :zero) + :inc",
                        "ExpressionAttributeNames": {"#rating": rating_attr},
                        "ExpressionAttributeValues": {
                            ":inc": {"N": "1"},
                            ":zero": {"N": "0"},
                        },
                    }
                },
            ]
        )
        print("Added review from {} to restaurant {}".format(username, restaurant))
        return True
    except Exception as e:
        print("Could not add review to restaurant")


create_review("Bev's Bistro", "hungryhank", 5, "Great food, great price!")

import boto3

from entities import Restaurant, Review

dynamodb = boto3.client("dynamodb")


def fetch_restaurant_summary(restaurant_name):
    resp = dynamodb.query(
        TableName="Restaurants",
        IndexName="GSI1",
        KeyConditionExpression="GSI1PK = :gsi1pk",
        ExpressionAttributeValues={
            ":gsi1pk": {"S": "REST#{}".format(restaurant_name)},
        },
        ScanIndexForward=False,
        Limit=6,
    )

    restaurant = Restaurant(resp["Items"][0])
    restaurant.reviews = [Review(item) for item in resp["Items"][1:]]

    return restaurant


restaurant = fetch_restaurant_summary("The Vineyard")

print(restaurant)
for review in restaurant.reviews:
    print(review)