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Documentation / @zerotal/orm / index / createReadWriteRouter

Function: createReadWriteRouter()

createReadWriteRouter(primary, replicas): SQLInstance

Defined in: packages/orm/src/db/ReadWriteRouter.ts:28

Transparent read/write routing for Bun SQL connections.

createReadWriteRouter() returns a SQLInstance-compatible proxy that:

• Routes SELECT / WITH / EXPLAIN / PRAGMA / SHOW / DESCRIBE → round-robin replica pool.
• Routes everything else (INSERT, UPDATE, DELETE, DDL, transactions) → primary.
• Delegates begin() (transactions) exclusively to the primary.
• Closes all unique connections on end().

The returned value is structurally identical to SQLInstance, so it is a drop-in replacement everywhere a connection is expected — DB.table(), BaseModel, and DB.raw() all route automatically with no code changes.

Parameters

primary

SQLInstance

The writable primary/master connection.

replicas

SQLInstance[]

One or more read-replica connections. Load-balanced round-robin. When empty, the primary is returned as-is (no overhead).

Returns

SQLInstance

Example

const primary = new SQL(env('DATABASE_URL'));
const replica = new SQL(env('REPLICA_URL'));
const router  = createReadWriteRouter(primary, [replica]);

// Drop-in: pass router wherever you'd pass a SQL connection
DB.table('users')  // SELECT → replica, mutating → primary