What is the difference between GCP Cloud Spanner and firestore?

Google Cloud Spanner and Firestore are both NoSQL databases provided by Google Cloud Platform (GCP), but they have different design principles and use cases.

1. Data Model:

• Cloud Spanner: It is a horizontally scalable, globally distributed relational database. It provides a schema-based data model similar to traditional relational databases, where data is organized into tables with rows and columns. It supports complex SQL queries and transactions.
• Firestore: It is a horizontally scalable, globally distributed document database. It uses a flexible, schemaless data model based on collections of documents, which are essentially key-value pairs or nested data structures (JSON-like). Firestore allows for quick and easy document retrieval and manipulation.

2. Scalability:

• Cloud Spanner: It is designed for scalability and can handle large datasets and high traffic volumes. It offers automatic scaling and distribution across multiple regions.
• Firestore: It is also designed for scalability and can handle high read and write loads. It automatically scales to accommodate traffic and storage requirements.

3. Consistency and Transactions:

• Cloud Spanner: It offers strong consistency and supports ACID (Atomicity, Consistency, Isolation, Durability) transactions across globally distributed data. It ensures that transactions are applied atomically and consistently across all replicas.
• Firestore: It provides eventual consistency by default, meaning that data changes may take some time to propagate across all replicas. However, it offers strong consistency within a single document or transactional batch. Firestore also supports ACID transactions, but they are limited to document-level operations within a single region.

4. Use Cases:

• Cloud Spanner: It is suitable for applications that require a globally consistent, scalable, and highly available relational database. It is often used for mission-critical, transactional workloads that involve complex queries and require strong consistency.
• Firestore: It is ideal for real-time applications and mobile or web apps that need fast, low-latency access to data. Firestore excels in scenarios where scalability, real-time updates, and offline capabilities are essential, such as chat apps, collaborative platforms, or content management systems.

5. Pricing Model:

• Cloud Spanner: It has a pricing model based on the resources provisioned, including storage, compute, and network usage. Costs can increase with the number of nodes, storage usage, and data transfer.
• Firestore: It has a pricing model based on the number of reads, writes, deletes, storage usage, and network egress. Costs can increase based on the operations performed and the amount of data stored and transferred.

In summary, Cloud Spanner is a globally consistent, horizontally scalable relational database suitable for complex, transactional workloads, while Firestore is a globally scalable document database designed for real-time applications and scenarios that prioritize fast access to data.