Laravel Read/Write Splitting & Sticky Reads | Mohamed Said [ ![Mohamed Said](https://cdn.msaied.com/01KT78WE565VEMM3PSNQAAB0MH.png) Mohamed Said Laravel Backend Engineer ](https://www.msaied.com) [ Home ](https://www.msaied.com) [ Projects ](https://www.msaied.com/projects) [ Articles ](https://www.msaied.com/articles) [ Certificates ](https://www.msaied.com/certificates) [ Contact ](https://www.msaied.com#contact-section) [ ](https://github.com/EG-Mohamed) [ Home ](https://www.msaied.com) [ Projects ](https://www.msaied.com/projects) [ Articles ](https://www.msaied.com/articles) [ Certificates ](https://www.msaied.com/certificates) [ Contact ](https://www.msaied.com#contact-section) [ home ](https://www.msaied.com) [ articles ](https://www.msaied.com/articles) Read/Write Splitting, Connection Pooling, and Sticky Reads in Laravel On this page 1. [ Why Read/Write Splitting Breaks More Apps Than It Fixes ](#why-readwrite-splitting-breaks-more-apps-than-it-fixes) 2. [ Configuring Read/Write Connections ](#configuring-readwrite-connections) 3. [ The sticky Option: What It Actually Does ](#the-codestickycode-option-what-it-actually-does) 4. [ Forcing a Connection Explicitly ](#forcing-a-connection-explicitly) 5. [ Connection Pooling: PgBouncer and ProxySQL ](#connection-pooling-pgbouncer-and-proxysql) 6. [ Takeaways ](#takeaways) ![Read/Write Splitting, Connection Pooling, and Sticky Reads in Laravel](https://cdn.msaied.com/543/97ef3abac42d00989679f44916e2efd5.png) #laravel #database #postgresql #mysql #performance Read/Write Splitting, Connection Pooling, and Sticky Reads in Laravel ======================================================================= 13 Aug 2026 4 min read ![Mohamed Said](https://cdn.msaied.com/01KT78WE565VEMM3PSNQAAB0MJ.jpg) Mohamed Said Table of contents 1. [ 01 Why Read/Write Splitting Breaks More Apps Than It Fixes ](#why-readwrite-splitting-breaks-more-apps-than-it-fixes) 2. [ 02 Configuring Read/Write Connections ](#configuring-readwrite-connections) 3. [ 03 The sticky Option: What It Actually Does ](#the-codestickycode-option-what-it-actually-does) 4. [ 04 Forcing a Connection Explicitly ](#forcing-a-connection-explicitly) 5. [ 05 Connection Pooling: PgBouncer and ProxySQL ](#connection-pooling-pgbouncer-and-proxysql) 6. [ 06 Takeaways ](#takeaways) Why Read/Write Splitting Breaks More Apps Than It Fixes ------------------------------------------------------- Adding a read replica feels like a free performance win. In practice, replication lag — even 50 ms — causes subtle, hard-to-reproduce bugs: a user creates a record, gets redirected, and the next page query hits the replica before the write has propagated. Laravel ships with first-class support for read/write connections, but the defaults are more dangerous than most engineers realise. --- Configuring Read/Write Connections ---------------------------------- Laravel's `config/database.php` accepts `read` and `write` keys inside any connection. The driver merges them with the top-level config, so you only override what differs: ```php 'mysql' => [ 'driver' => 'mysql', 'read' => [ 'host' => [ env('DB_READ_HOST_1', '10.0.1.11'), env('DB_READ_HOST_2', '10.0.1.12'), ], ], 'write' => [ 'host' => env('DB_WRITE_HOST', '10.0.1.10'), ], 'sticky' => true, 'database' => env('DB_DATABASE', 'app'), 'username' => env('DB_USERNAME', 'app'), 'password' => env('DB_PASSWORD', ''), 'charset' => 'utf8mb4', 'collation' => 'utf8mb4_unicode_ci', 'prefix' => '', ], ``` When multiple hosts are listed under `read`, Laravel picks one at random per request — a simple but effective load-distribution strategy. --- The `sticky` Option: What It Actually Does ------------------------------------------ With `'sticky' => true`, Laravel tracks whether a write query has been executed during the current request lifecycle. If it has, **all subsequent reads for that request are routed to the write connection**, bypassing the replica entirely. This is implemented in `Illuminate\Database\Connection` via a simple boolean flag: ```php // Simplified from the framework source if ($this->recordsHaveBeenModified() && $this->getConfig('sticky')) { return $this->getWritePdo(); } return $this->getReadPdo(); ``` The flag is reset at the start of each request via the `DatabaseServiceProvider`, so there is no cross-request leakage in FPM. Under **Laravel Octane**, however, the connection object is reused across requests — you must call `DB::resetRecordsModified()` in an `octane:request` listener or use a middleware: ```php // app/Http/Middleware/ResetDbStickyFlag.php public function handle(Request $request, Closure $next): Response { DB::connection()->resetRecordsModified(); return $next($request); } ``` Register it early in the global middleware stack. --- Forcing a Connection Explicitly ------------------------------- Sometimes you need deterministic routing regardless of sticky state — for example, an admin dashboard that must always read fresh data: ```php $users = DB::connection('mysql::write') ->table('users') ->where('active', true) ->get(); ``` Or with Eloquent: ```php User::on('mysql::write')->where('active', true)->get(); // Alternatively, use the useWritePdo() scope: User::query()->useWritePdo()->where('active', true)->get(); ``` `useWritePdo()` is available on the query builder directly and is the cleanest option for one-off overrides. --- Connection Pooling: PgBouncer and ProxySQL ------------------------------------------ Laravel opens a new PDO connection per worker process. Under FPM with 50 workers × 4 app servers, you can exhaust PostgreSQL's `max_connections` (default 100) instantly. **PgBouncer** (PostgreSQL) in `transaction` pooling mode is the standard solution. Each query borrows a server connection for its duration, then returns it to the pool. Your Laravel `DB_HOST` points to PgBouncer, not Postgres directly. Key caveats with PgBouncer transaction mode: - `SET` statements and advisory locks are **not safe** — they do not persist across queries. - Prepared statements require `server_reset_query` or disabling them in Laravel: set `'options' => [PDO::ATTR_EMULATE_PREPARES => true]` in your connection config. **ProxySQL** serves the same role for MySQL/MariaDB and additionally supports query routing rules — you can route `SELECT` statements to replicas and writes to the primary at the proxy layer, removing that concern from application config entirely. --- Takeaways --------- - Enable `sticky` on every read/write split config — replication lag bugs are silent and costly. - Under Octane, reset the modified flag explicitly; FPM handles it automatically. - Use `useWritePdo()` for admin or post-write reads that must be consistent. - Point Laravel at PgBouncer/ProxySQL rather than the database directly to avoid connection exhaustion. - Disable PDO prepared statements when using PgBouncer in transaction pooling mode. - Test replica routing in CI by asserting which connection a query targets using `DB::listen()`. Found this useful? [ ](https://twitter.com/intent/tweet?url=https%3A%2F%2Fwww.msaied.com%2Farticles%2Freadwrite-splitting-connection-pooling-and-sticky-reads-in-laravel-6&text=Read%2FWrite+Splitting%2C+Connection+Pooling%2C+and+Sticky+Reads+in+Laravel) [ ](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fwww.msaied.com%2Farticles%2Freadwrite-splitting-connection-pooling-and-sticky-reads-in-laravel-6) Frequently Asked Questions ---------------------------- 3 questions Q01 Does Laravel's sticky option work across multiple requests? No. Under PHP-FPM the sticky flag is reset at the start of each request. Under Octane, connections are reused, so you must reset it manually with DB::resetRecordsModified() in a middleware or Octane request listener. Q02 Can I use PgBouncer in transaction pooling mode with Laravel's default PDO settings? Not safely. Transaction pooling does not preserve prepared statement state between queries. Set PDO::ATTR_EMULATE_PREPARES to true in your connection options, or switch PgBouncer to session pooling if you need native prepared statements. Q03 When should I route reads at the proxy layer (ProxySQL) vs. in Laravel config? Proxy-layer routing is better when you have multiple applications sharing the same database cluster, or when you want to change routing rules without deploying application code. Laravel-level config is simpler for single-app setups and gives you fine-grained per-query control. 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