Module factory 

PostgreSQL backend factory with shared LISTEN/NOTIFY polling.

PostgresStorageFactory creates independent PostgreSQL backends while sharing a single PostgreSQL notification listener. Each backend is registered by its queue name and receives task IDs for newly inserted jobs belonging to that queue.

This avoids creating a separate PgListener for every worker and allows multiple queue types to share the same database connection pool.

The factory creates PostgresStorage instances configured with StreamStrategy. PostgreSQL notifications wake the corresponding backend, which then performs its normal database polling.

Example

use apalis::prelude::*;
use apalis_postgres::factory::PostgresStorageFactory;
use sqlx::PgPool;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let pool = PgPool::connect(
        &std::env::var("DATABASE_URL")?
    ).await?;

    let mut factory = PostgresStorageFactory::new(pool);

    let mut backend = factory.create()?;

    backend.push(42).await?;

    let worker = WorkerBuilder::new("numbers")
        .backend(backend)
        .build(|task: u64| async move {
            println!("processing {task}");
        });

    worker.run().await?;
    Ok(())
}

A factory can also create multiple queues. Each queue is independently notified when a matching job is inserted:

let mut factory = PostgresStorageFactory::new(pool);

let emails = factory.create::<Email>()?;
let reports = factory.create::<Report>()?;

Structs

PostgresStorageFactory

A factory for creating PostgreSQL-backed task queues.

SharedFetcher

A stream of task IDs received from the shared PostgreSQL notification listener.

Enums

PostgresFactoryError

Errors returned when creating a PostgreSQL backend from a PostgresStorageFactory.