Laravel Read/Write Database Separation Configuration Guide

In high‑concurrency scenarios a single database server can become a bottleneck and a single point of failure; separating read and write operations onto different servers mitigates this risk.

Read/write separation basics : SELECT statements are treated as read operations, while INSERT, UPDATE and DELETE statements are treated as write operations. Laravel supports read/write splitting through raw SQL, the query builder, or Eloquent ORM.

Configuration when read and write servers share the same credentials can be done in config/database.php as follows:

<?php
'mysql' => [
    'read' => [
        'host' => [
            '192.168.100.101',
            '196.168.100.102',
        ],
    ],
    'write' => [
        'host' => [
            '196.168.100.103',
        ],
    ],
    'sticky' => true,
    'driver' => 'mysql',
    'database' => 'your_database',
    'username' => 'your_username',
    'password' => 'your_password',
    'charset' => 'utf8mb4',
    'collation' => 'utf8mb4_unicode_ci',
    'prefix' => '',
];

The read key defines the hosts used for read‑only queries, while the write key defines the hosts used for write queries. The sticky option, when set to true, forces all subsequent reads in the same request to use the write connection after a write has occurred, ensuring immediate visibility of newly written data.

Configuration when read and write servers have different credentials requires specifying the username and password for each connection individually:

<?php
'mysql' => [
    'read' => [
        [
            'host' => '192.168.100.101',
            'username' => 'your_username',
            'password' => 'your_password',
        ],
    ],
    'write' => [
        [
            'host' => '192.168.100.103',
            'username' => 'your_username',
            'password' => 'your_password',
        ],
    ],
    'sticky' => true,
    'driver' => 'mysql',
    'database' => 'your_database',
    'charset' => 'utf8mb4',
    'collation' => 'utf8mb4_unicode_ci',
    'prefix' => '',
];

When the database accounts and passwords differ across servers, each server’s credentials must be configured separately as shown above.

Laravel makes read/write separation straightforward, but the exact configuration depends on the underlying database architecture. Future articles will demonstrate a three‑server setup that aligns with the concepts presented here.