Initially, thinking D is the best answer but when question is re-re-read, A seems to be correct answer for following reasons 1. Is payment TRANSACTION -- DB should able to perform full blown transaction (updating inventory, sales info etc, though not specified) , not just ATOMIC which DataStore provides 2. Its point-of-sale application, not ONLINE STORE where HIGH number of concurrent users ordering stuff. 3. User Base could grow exponentially - again more users does mot mean concurrent users and more processing power. Its only about storage. 4. Do not want to Manage infrastructure scaling. - Cloud SQL can scale in terms of storage. 5. CloudStore is poor selection for OLTP application - Each property is index - so higher latency Not sure, during exam 2 min is enough to think on various point.. I may be wrong or wrong path ... lets brainstrom..

D seems to be the right one. Cloud SQL doesn't automatically scale

Cloud Datastore (now part of Google Cloud Firestore in Datastore mode) is designed for high scalability and ease of management for applications. It is a NoSQL document database built for automatic scaling, high performance, and ease of application development. It's serverless, meaning it handles the scaling, performance, and management automatically, fitting your requirement of not wanting to manage infrastructure scaling. Cloud SQL, while a fully-managed relational database service that makes it easy to set up, manage, and administer your SQL databases, is not as automatically scalable as Datastore. It's better suited for applications that require a traditional relational database.

D - Because DataStore supports massive scaling and ACID transactions which are two primary considerations in this scenario.

B - not an option C - lack of ACID transactions A - lack of resource automatic scalability D - (correct, IMHO) support ACID, suitable for OLPT and scalable enough

B - not an option C - lack of ACID transactions A - lack of resource automatic scalability D - (correct, IMHO) support ACID, suitable for OLPT and scalable enough

For a point-of-sale application where you anticipate exponential growth and want to ensure seamless scalability without managing the infrastructure scaling, the best choice among the provided options is: D. Cloud Datastore Cloud Datastore is a NoSQL database service that's built for web, mobile, and IoT applications. It provides automatic scaling, high performance, and ease of application development, making it a suitable choice for applications where the user base could grow exponentially and where you don't want to manually handle infrastructure scaling.

Bigtable is the better answer. Neither Cloud SQL & Datastore (Firestore) can scale to exponential level....

A seems to be correct. Usecase here is "process payment transactions in a point-of-sale application". So this is OLTP. Datastore is not a relational database, and it is not an effective solution for analytic data. If you need a relational database with full SQL support for an online transaction processing (OLTP) system, consider Cloud SQL. https://cloud.google.com/datastore/docs/concepts/overview

D is correct because you do not want to manage scaling in this case. Cloud SQL can also scale but it needs involvement unlike Datastore which is completely automatic.

Its D, though Datastore is NoSQL, but it supports ACID transaction concepts.

Correct Answer is D, Cloud Datastore is used for PoS https://cloud.google.com/blog/topics/developers-practitioners/your-google-cloud-database-options-explained

Datastore automatically scales and is highly opted for ACID transactions.

cloud sql --> incorrect https://cloud.google.com/sql#section-8 --> you will need to manually do scalability Scalability --> Easily scale up as your data grows—add processor cores, RAM and storage, and scale out by adding read replicas to handle increasing read traffic. Read replicas support high availability, can have their own read replicas, and can be located across regions and platforms. big query , big table --> doesn't support ACID Cloud DataStore --> CORRECT ( https://cloud.google.com/datastore/) check features section ACID transactions Ensure the integrity of your data by executing multiple datastore operations in a single transaction with ACID characteristics, so all the grouped operations succeed or all fail. Fully managed Datastore is fully managed, which means Google automatically handles sharding and replication in order to provide you with a highly available and consistent database.

BigQuery --> OLAP , DataWareHouse Cloud BigTable --> NOSQL, Doesn't support ACID. Cloud DataStore --> NO SQL

Bard said it's cloud sql: "If Cloud Spanner is not an option, Cloud SQL is a good choice for your point-of-sale application. It offers a managed service, flexible pricing, security, and global availability."

It should be cloud SQL