How do you implement database read replicas in NestJS for read/write splitting with TypeORM?

Q: How do you implement database read replicas in NestJS for read/write splitting with TypeORM?

TypeOrmModule.forRoot({ type: 'postgres', replication: { master: { host: process.env.DB_MASTER_HOST, username: process.env.DB_USER, password: process.env.DB_PASS, database: process.env.DB_NAME, }, slaves: [ { host: process.env.DB_REPLICA_1_HOST, username: process.env.DB_USER, password: process.env.DB_PASS, database: process.env.DB_NAME, }, { host: process.env.DB_REPLICA_2_HOST, username: process.env.DB_USER, password: process.env.DB_PASS, database: process.env.DB_NAME, }, ], }, entities: [__dirname + '/**/*.entity{.ts,.js}'], }) // Force read from master — read-your-writes after a mutation const user = await this.dataSource .createQueryBuilder(User, 'user') .setQueryRunner( await this.dataSource.createQueryRunner('master'), // explicit master ) .where('user.id = :id', { id }) .getOne(); TypeORM automatically routes writes to master and reads to slaves — no code changes needed. Slaves are selected in round-robin order — traffic is distributed evenly across replicas. Force master reads immediately after a write to avoid replication lag causing stale reads. createQueryRunner('master') bypasses the replica routing for a specific query. Monitor replication lag — a slow replica serving stale data on reads can cause subtle bugs.

Difficulty: 6/10

read replicas, TypeORM connection management, NestJS module configuration

Use the replication option in TypeOrmModule.forRoot() to define master and slave connection details. TypeORM automatically routes write operations (INSERT, UPDATE, DELETE) to the master and read operations (SELECT) to slaves in round-robin. Force master reads by creating a QueryRunner with the 'master' option for read-your-writes consistency after mutations.

TypeORM read replica configuration

Read replica routing rules:

1
TypeORM automatically routes writes to master and reads to slaves — no code changes needed.
2

How do you implement database read replicas in NestJS for read/write splitting with TypeORM?

Difficulty: 6/10

read replicas, TypeORM connection management, NestJS module configuration

Use the replication option in TypeOrmModule.forRoot() to define master and slave connection details. TypeORM automatically routes write operations (INSERT, UPDATE, DELETE) to the master and read operations (SELECT) to slaves in round-robin. Force master reads by creating a QueryRunner with the 'master' option for read-your-writes consistency after mutations.

TypeORM read replica configuration

Read replica routing rules:

1
TypeORM automatically routes writes to master and reads to slaves — no code changes needed.
2

How do you implement database read replicas in NestJS for read/write splitting with TypeORM?

How do you implement database read replicas in NestJS for read/write splitting with TypeORM?

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