71 lines
2.4 KiB
Markdown
71 lines
2.4 KiB
Markdown
|
---
|
||
|
|
stage: Data Stores
|
||
|
|
group: Database
|
||
|
|
info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
|
||
|
|
---
|
||
|
|
|
||
|
|
# Query Count Limits
|
||
|
|
|
||
|
|
Each controller or API endpoint is allowed to execute up to 100 SQL queries and
|
||
|
|
in test environments we raise an error when this threshold is exceeded.
|
||
|
|
|
||
|
|
## Solving Failing Tests
|
||
|
|
|
||
|
|
When a test fails because it executes more than 100 SQL queries there are two
|
||
|
|
solutions to this problem:
|
||
|
|
|
||
|
|
- Reduce the number of SQL queries that are executed.
|
||
|
|
- Disable query limiting for the controller or API endpoint.
|
||
|
|
|
||
|
|
You should only resort to disabling query limits when an existing controller or endpoint
|
||
|
|
is to blame as in this case reducing the number of SQL queries can take a lot of
|
||
|
|
effort. Newly added controllers and endpoints are not allowed to execute more
|
||
|
|
than 100 SQL queries and no exceptions are made for this rule. _If_ a large
|
||
|
|
number of SQL queries is necessary to perform certain work it's best to have
|
||
|
|
this work performed by Sidekiq instead of doing this directly in a web request.
|
||
|
|
|
||
|
|
## Disable query limiting
|
||
|
|
|
||
|
|
In the event that you _have_ to disable query limits for a controller, you must first
|
||
|
|
create an issue. This issue should (preferably in the title) mention the
|
||
|
|
controller or endpoint and include the appropriate labels (`database`,
|
||
|
|
`performance`, and at least a team specific label such as `Discussion`).
|
||
|
|
|
||
|
|
After the issue has been created, you can disable query limits on the code in question. For
|
||
|
|
Rails controllers it's best to create a `before_action` hook that runs as early
|
||
|
|
as possible. The called method in turn should call
|
||
|
|
`Gitlab::QueryLimiting.disable!('issue URL here')`. For example:
|
||
|
|
|
||
|
|
```ruby
|
||
|
|
class MyController < ApplicationController
|
||
|
|
before_action :disable_query_limiting, only: [:show]
|
||
|
|
|
||
|
|
def index
|
||
|
|
# ...
|
||
|
|
end
|
||
|
|
|
||
|
|
def show
|
||
|
|
# ...
|
||
|
|
end
|
||
|
|
|
||
|
|
def disable_query_limiting
|
||
|
|
Gitlab::QueryLimiting.disable!('https://gitlab.com/gitlab-org/...')
|
||
|
|
end
|
||
|
|
end
|
||
|
|
```
|
||
|
|
|
||
|
|
By using a `before_action` you don't have to modify the controller method in
|
||
|
|
question, reducing the likelihood of merge conflicts.
|
||
|
|
|
||
|
|
For Grape API endpoints there unfortunately is not a reliable way of running a
|
||
|
|
hook before a specific endpoint. This means that you have to add the allowlist
|
||
|
|
call directly into the endpoint like so:
|
||
|
|
|
||
|
|
```ruby
|
||
|
|
get '/projects/:id/foo' do
|
||
|
|
Gitlab::QueryLimiting.disable!('...')
|
||
|
|
|
||
|
|
# ...
|
||
|
|
end
|
||
|
|
```
|