# Cloud SQL, AlloyDB and Spanner — Google Cloud Platform

Source: https://www.skillbyai.com/en/gcp/d-relational

> Pick a managed relational database for the scale and consistency you need.

## Three relational options

**Cloud SQL** is managed MySQL, PostgreSQL and SQL Server: automated backups, point-in-time recovery, patching and **high availability** through a regional instance with a standby in another zone and automatic failover. **Read replicas** offload reads, including in other regions. **AlloyDB for PostgreSQL** is a PostgreSQL-compatible database built for higher performance, with a columnar engine for analytical queries alongside transactions. **Spanner** is a horizontally scalable relational database with strong consistency, SQL and transactions across regions, using Google's TrueTime clocks; it suits global systems that outgrow a single primary, such as large payment or inventory systems. Connect to Cloud SQL using **private IP** or the **Cloud SQL Auth Proxy** and language connectors, which handle TLS and IAM-based authentication, instead of opening the database to `0.0.0.0/0`.

## An HA PostgreSQL instance and a secure connection

IAM database authentication avoids storing a database password for the app.

```bash
gcloud sql instances create shop-pg --database-version=POSTGRES_16 \
  --region=asia-south1 --availability-type=REGIONAL \
  --tier=db-custom-2-7680 --storage-auto-increase \
  --database-flags=cloudsql.iam_authentication=on

gcloud sql databases create shop --instance=shop-pg
gcloud sql users create orders-api@shop-dev-123456.iam --instance=shop-pg \
  --type=cloud_iam_service_account

# local development through the Auth Proxy (listens on 127.0.0.1:5432)
cloud-sql-proxy --auto-iam-authn shop-dev-123456:asia-south1:shop-pg
```

## Car, sports car and train network

Cloud SQL is a reliable family car, AlloyDB a faster car that also tows analytics, and Spanner a national rail network: built for enormous scale across cities, and overkill for a trip to the market.

**Quiz:** Which option gives Cloud SQL automatic failover to another zone?

- [ ] A read replica in the same zone
- [ ] Larger storage
- [ ] Public IP
- [x] Availability type REGIONAL (high availability)

*Answer:* Availability type REGIONAL (high availability). A regional (HA) instance keeps a standby in another zone and fails over automatically.