OeditusCredo.Check.Warning.InefficientFilter (OeditusCredo v0.5.0)

Basics

This check has a base priority of high and works with any version of Elixir.

Explanation

Using Repo.all() followed by Enum.filter is inefficient and should be done in SQL.

Filtering data after fetching it from the database wastes memory and processing power. Use Ecto query's where/3 to filter in the database.

Bad:

users = Repo.all(User)
active_users = Enum.filter(users, & &1.active)

Good:

import Ecto.Query
active_users = User |> where([u], u.active == true) |> Repo.all()

Check-Specific Parameters

Use the following parameters to configure this check:

:exclude_test_files

Set to true to skip test files (default: false)

This parameter defaults to nil.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.