Databases in Google Cloud

 We all know about different types of Databases. Just highlighting them to start off the topic.

Relational DB:

• Fixed table schema and relations (primary and foreign key)
• Strong transactional capability
• Update all table data in one transaction and commit
• Failure of one, implies rollback in all.
• Since its strong in transactions, Relational DB is preferred for OLTP (Online transaction processing) systems like banking.
• Lots of transactions (large number of users and small transactions per user)
• Data is stored in row storage
• In Google Cloud we have
• Cloud SQL
• Supports MySQL, SQL server and PostgreSQL
• Regional Database
• Multi zone for High availability
• Can't create Global Cloud SQL DB
• Data upto a few TB
• Fully managed (replication, patch management, DB management etc)
• Public IP provided to connect to the DB
• Cloud shell option also provided in console (gcloud sql command)
• Enable Cloud SQL Admin API as a pre-requisite
• Cloud Spanner
• Unlimited scale
• Horizontal scaling
• High availability
• Global applications (Globally consistent)
• Fully managed
• Multi region
• Option to add compute capacity when being configured
• 1 node = 1000 processing units
• Compute cost is the hourly cost charge for nodes or processing units.
• Storage cost is separate and billed per GB per month
• Min 100 processing units or 1 node

• Can be used for Analytics as well (OLAP - Online Analytics Processing)
• Used to analyze huge amount of data
• Reporting, data warehouse
• Uses columnar storage (not row) [High compression]
• Since data is stored via columns, it can be distributed
• Queries can run over multiple nodes (efficient execution for complex queries)
• GCP Managed service is BigQuery

NO SQL DB: (Not only SQL)

• Flexible schema
• Scales horizontally
• Highly scalable
• High performance
• GCP managed No SQL service:
• Cloud Firestore (Data store)
• Serverless
• Document DB
• Can run SQL like queries
• Used for high transactions
• Mobile and web applications
• Small to medium DB (few TB)
• BigTable
• Scalable
• Wide column DB
• Not serverless
• Data size > 10TB
• Does not support multi row transaction. Supports only single row.
• Not to be used for transactional applications

In Memory Database

• Faster to retrieve data since data is not on the disk
• Low latency (microseconds)
• Persistent data stored in memory
• Use for caching or session management
• GCP service is Managed Store