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Posted on • Originally published at dingjiu1989-hue.github.io

Database Scalability

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Database Scalability

Database Scalability

Database Scalability

Database Scalability

Database Scalability

Database Scalability

Database Scalability

Database Scalability

Database Scalability

Database Scalability

Database Scalability

Database Scalability

Database Scalability

Scalability Options

Database scalability options range from simple to complex. Start with the simplest approach and evolve.

Vertical Scaling

Upgrade to a larger server with more CPU, RAM, and storage.

AWS RDS instance upgrade

resource "aws_db_instance" "main" {

instance_class = "db.r6g.8xlarge" # 32 vCPU, 256GB RAM

allocated_storage = 5000 # 5TB SSD

}

Simple but has a cost ceiling and hardware limits.

Read Replicas

Offload read traffic to replicas:

class DatabaseRouter:

def init(self, primary, replicas):

self.primary = primary

self.replicas = replicas

def get_conn(self, write=False):

if write:

return self.primary

return random.choice(self.replicas)

Route reads to replicas, writes to primary

db_router.get_conn(write=True).execute("INSERT INTO ...")

results = db_router.get_conn(write=False).execute("SELECT ...")

Effective for read-heavy workloads. Does not help with write scaling.

Caching

Reduce database load with in-memory caching:

def get_user(user_id):

user = cache.get(f"user:{user_id}")

if not user:

user = db.query("SELECT * FROM users WHERE id = %s", user_id)

cache.setex(f"user:{user_id}", 3600, json.dumps(user))

return user

Horizontal Scaling (Sharding)

Distribute data across multiple database servers:

class ShardManager:

def init(self, shards):

self.shards = shards

def get_shard(self, customer_id):

return self.shards[hash(customer_id) % len(self.shards)]

Most complex. Use tools like Vitess, Citus, or CockroachDB.

Scaling Decision Tree

Is DB overloaded?

├── Read-heavy? → Add read replicas

├── Write-heavy?

│ ├── Can you cache? → Add Redis/memcached

│ └── Cache insufficient? → Shard

└── Both? → Scale vertically first, then shard

Conclusion

Scale vertically first (simple). Add read replicas for read loads. Add caching for repeated queries. Shard only when necessary. Monitor your bottleneck before choosing a strategy. Most applications never need sharding.

See also: Database Horizontal Scaling Strategies, Read Replicas: Scaling Reads, Replication Lag, and Failover, Redis Caching Patterns.

See also: Database Horizontal Scaling Strategies, Read Replicas: Scaling Reads, Replication Lag, and Failover, Database Capacity Planning: Sizing, Growth Forecasting, and Scaling

See also: Database Horizontal Scaling Strategies, Read Replicas: Scaling Reads, Replication Lag, and Failover, Database Capacity Planning: Sizing, Growth Forecasting, and Scaling


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