The DynamicPartitioner plugin manages a partitioned oban_jobs table for optimized query performance, minimal database bloat, and efficiently pruned historic jobs. Partitioning can minimize database bloat for tables of any size, but it's ideally suited for high throughput applications that run millions of jobs a week.

Partitioning is only officially supported on Postgres 11 and higher. While older versions of Postgres support partitioning, they have prohibitive technical limitations and your experience may vary.

Installation

Before running the DynamicPartitioner plugin, you must run a migration to create a partitioned oban_jobs table to your database.

Table Name Conflicts

Existing oban_jobs tables can't be converted to a partitioned table in place and require a transition stage. The migration will automatically handle table conflicts by renaming the existing table to oban_jobs_old. However, if the partitioned table is added to a different prefix without a conflict, then the original table is left untouched and both tables are named oban_jobs.

See the Backfilling and Migrating section for strategies before running migrations.

mix ecto.gen.migration add_partitioned_oban_jobs

Open the generated migration in your editor and delegate to the dynamic partitions migration:

defmodule MyApp.Repo.Migrations.AddPartitionedObanJobs do
  use Ecto.Migration

  defdelegate change, to: Oban.Pro.Migrations.DynamicPartitioner
end

As with the standard oban_jobs table, you can optionally provide a prefix to "namespace" the table within your database. Here we specify a "partitioned" prefix:

defmodule MyApp.Repo.Migrations.AddPartitionedObanJobs do
  use Ecto.Migration

  def change do
    Oban.Pro.Migrations.DynamicPartitioner.change(prefix: "partitioned")
  end
end

Run the migration to create the new table:

mix ecto.migrate

The new table is partitioned for optimal inserts, ready for you to backfill any existing jobs and configure retention periods.

Backfilling and Migrating

Below are several recommended strategies for backfilling original jobs into the new partitioned table. They're listed in order of complexity, beginning with the least invasive approach.

Strategy 1: Don't Backfill at All

The most performant strategy is to not backfill jobs at all. It's perfectly acceptable to leave old jobs untouched if you don't need them for uniqueness checks or other observability concerns. Though, in an active system, you'll still want to finish processing jobs in the original table.

During the transition period, until all of the original jobs are processed, you'll run two separate, entirely isolated, Oban instances:

1. Original — configured with the original prefix, public if you never changed it. This instance will run all of the original queues, without any plugins and it won't insert new jobs.

2. Partitioned — configured with the new prefix for the partitioned table, all of your original queues, plugins, and any other options.

Here's an example of that configuration:

queues = [
  default: 10,
  other_queue: 10,
  and_another: 10
]

config :my_app, Oban.Original, queues: queues

config :my_app, Oban,
  prefix: "partitioned",
  queues: queues,
  plugins: [
    ...

Now, start both Oban instances within your application's supervisor:

 children = [
   MyApp.Repo,
   {Oban, Application.fetch_env!(:my_app, Oban)},
+  {Oban, Application.fetch_env!(:my_app, Oban.Original)},
   ...
 ]

New jobs will be inserted into the partitioned table while existing jobs keep processing through the Oban.Original instance. Once the all original jobs have executed you're free to remove the extra instance and drop the original table.

Strategy 2: Backfill Old Jobs

This strategy moves old jobs automatically as part of a migration. The backfill/1 migration helper, which delegates to backfill_jobs/2, helps move jobs in batches for each state.

By default, backfilling includes all states and is intended for smaller tables, i.e. 50k-100k total jobs.

Backfill by creating an additional migration with ddl transaction disabled:

defmodule MyApp.Repo.Migrations.BackfillPartitionedObanJobs do
  use Ecto.Migration

  @disable_ddl_transaction true

  def change do
    Oban.Pro.Migrations.DynamicPartitioner.backfill()
  end
end

Like all other migrations, backfill/1 accepts options to control the table's prefix. You can specify both old and new prefixes to handle situations where the partitioned table lives in a different prefix:

def change do
  Oban.Pro.Migrations.DynamicPartitioner.backfill(new_prefix: "private", old_prefix: "public")
end

For larger tables, or applications that are sensitive to longer migrations, you can split backfilling between migrations and prioritize in-flight jobs.

Use the states option to restrict backfilling to actively executing jobs:

def change do
  Oban.Pro.Migrations.DynamicPartitioner.backfill(states: ~w(executing))
end

For the remaining jobs, you can either use a secondary migration or manually call backfill_jobs/1 from your application code.

See backfill_jobs/1 for the full range of backfill options including changing the batch size and automatically sleeping between batches.

Cleaning Up

After backfilling is complete you can drop the original oban_jobs table. Be very careful to ensure you're dropping the old job table! If the new and old prefix was the same, which it is by default, then the table has _old appended.

defmodule MyApp.Repo.Migrations.DropStandardObanJobs do
  use Ecto.Migration

  def change do
    drop_if_exists table(:oban_jobs_old)
  end
end

Using and Configuring

After running the migration to partition tables, enable the plugin to manage sub-partitions:

config :my_app, Oban,
  plugins: [Oban.Pro.Plugins.DynamicPartitioner]
  ...

The plugin will preemptively create sub-partitions for finished job states (completed, cancelled, discarded) as well as prune partitions older than the retention period. By default, older jobs are retained for 3 days.

You can override the retention period for states individually. For example, to retain completed jobs for 2 days, cancelled for 7, and discarded for 30:

plugins: [{
  Oban.Pro.Plugins.DynamicPartitioner,
  retention: [completed: 2, cancelled: 7, discarded: 30
}]

Pruning sub-partitions is an extremely fast operation akin to dropping a table. As a result, there is zero lingering bloat, but it's incompatible with other pruners. Be sure to remove any pruners from your plugins:

plugins: [
  Oban.Pro.Plugins.DynamicPartitioner,
- Oban.Plugins.Pruner,
- Oban.Pro.Plugins.DynamicPruner
]

DynamicPartitioner will warn you if any pruners are enabled at the same time.

Tuning Partition Management

The partitioner attempts once an hour to pre-create partitions two days in advance. That schedule and buffer should be suitable for most applications. However, you can increase the buffer period and set an alternate schedule if necessary.

For example, to increase the buffer to 3 days and run at 05:00 in the Europe/Paris timezone:

plugins: [{
  Oban.Pro.Plugins.DynamicPartitioner,
  buffer: 3,
  schedule: "0 5 * * *",
  timezone: "Europe/Paris"
}]

Instrumenting with Telemetry

The DynamicPartitioner plugin doesn't add any metadata to the [:oban, :plugin, :stop] event.