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Cloud Platforms > Google Cloud Platform (GCP) > Cloud Datastore

Cloud Datastore

Author: Venkata Sudhakar

Google Cloud Datastore is a highly scalable, fully managed NoSQL document database service built for automatic scaling, high performance, and ease of application development. It is now part of Cloud Firestore in Datastore mode.

Key Features:

1. Schemaless - No fixed schema; entities can have different properties.

2. ACID transactions - Supports strongly consistent transactions.

3. SQL-like queries - GQL (Google Query Language) for querying entities.

4. Auto-scaling - Scales automatically to handle any load.

5. Fully managed - No servers to provision or manage.

The below example shows how to store and retrieve entities using Cloud Datastore Java client.

import com.google.cloud.datastore.Datastore;
import com.google.cloud.datastore.DatastoreOptions;
import com.google.cloud.datastore.Entity;
import com.google.cloud.datastore.Key;
import com.google.cloud.datastore.KeyFactory;
import com.google.cloud.datastore.Query;
import com.google.cloud.datastore.QueryResults;
import com.google.cloud.datastore.StructuredQuery;

public class CloudDatastoreExample {
    public static void main(String[] args) {
        Datastore datastore = DatastoreOptions.getDefaultInstance().getService();
        KeyFactory keyFactory = datastore.newKeyFactory().setKind("Employee");

// Create and save an entity
        Key employeeKey = datastore.allocateId(keyFactory.newKey());
        Entity employee = Entity.newBuilder(employeeKey)
            .set("name", "John Doe")
            .set("department", "Engineering")
            .set("salary", 95000)
            .build();
        datastore.put(employee);
        System.out.println("Saved employee: " + employee.getString("name"));

// Query entities
        Query<Entity> query = Query.newEntityQueryBuilder()
            .setKind("Employee")
            .setFilter(StructuredQuery.PropertyFilter.eq("department", "Engineering"))
            .build();

QueryResults<Entity> results = datastore.run(query);
        System.out.println("Engineering employees:");
        while (results.hasNext()) {
            Entity e = results.next();
            System.out.println("  - " + e.getString("name") + 
                " (Salary: " + e.getLong("salary") + ")");
        }
    }
}

It gives the following output,

Saved employee: John Doe
Engineering employees:
  - John Doe (Salary: 95000)

Datastore Concepts:

Kind - Similar to a table in RDBMS; groups entities of the same type.

Entity - Similar to a row; the unit of data in Datastore.

Key - Uniquely identifies an entity; can be auto-generated or user-defined.

Property - Similar to a column; named values stored in an entity.

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