cd64e88711
* PERF: Improve database query perf when loading topics for a category.
Instead of left joining the `topics` table against `categories` by filtering with `categories.id`,
we can improve the query plan by filtering against `topics.category_id`
first before joining which helps to reduce the number of rows in the
topics table that has to be joined against the other tables and also
make better use of our existing index.
The following is a before and after of the query plan for a category
with many subcategories.
Before:
```
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------
Limit (cost=1.28..747.09 rows=30 width=12) (actual time=85.502..2453.727 rows=30 loops=1)
-> Nested Loop Left Join (cost=1.28..566518.36 rows=22788 width=12) (actual time=85.501..2453.722 rows=30 loops=1)
Join Filter: (category_users.category_id = topics.category_id)
Filter: ((topics.category_id = 11) OR (COALESCE(category_users.notification_level, 1) <> 0) OR (tu.notification_level > 1))
-> Nested Loop Left Join (cost=1.00..566001.58 rows=22866 width=20) (actual time=85.494..2453.702 rows=30 loops=1)
Filter: ((COALESCE(tu.notification_level, 1) > 0) AND ((topics.category_id <> 11) OR (topics.pinned_at IS NULL) OR ((t
opics.pinned_at <= tu.cleared_pinned_at) AND (tu.cleared_pinned_at IS NOT NULL))))
Rows Removed by Filter: 1
-> Nested Loop (cost=0.57..528561.75 rows=68606 width=24) (actual time=85.472..2453.562 rows=31 loops=1)
Join Filter: ((topics.category_id = categories.id) AND ((categories.topic_id <> topics.id) OR (categories.id = 1
1)))
Rows Removed by Join Filter: 13938306
-> Index Scan using index_topics_on_bumped_at on topics (cost=0.42..100480.05 rows=715549 width=24) (actual ti
me=0.010..633.015 rows=464623 loops=1)
Filter: ((deleted_at IS NULL) AND ((archetype)::text <> 'private_message'::text))
Rows Removed by Filter: 105321
-> Materialize (cost=0.14..36.04 rows=30 width=8) (actual time=0.000..0.002 rows=30 loops=464623)
-> Index Scan using categories_pkey on categories (cost=0.14..35.89 rows=30 width=8) (actual time=0.006.
.0.040 rows=30 loops=1)
Index Cond: (id = ANY ('{11,53,57,55,54,56,112,94,107,115,116,117,97,95,102,103,101,105,99,114,106,1
13,104,98,100,96,108,109,110,111}'::integer[]))
-> Index Scan using index_topic_users_on_topic_id_and_user_id on topic_users tu (cost=0.43..0.53 rows=1 width=16) (a
ctual time=0.004..0.004 rows=0 loops=31)
Index Cond: ((topic_id = topics.id) AND (user_id = 1103877))
-> Materialize (cost=0.28..2.30 rows=1 width=8) (actual time=0.000..0.000 rows=0 loops=30)
-> Index Scan using index_category_users_on_user_id_and_last_seen_at on category_users (cost=0.28..2.29 rows=1 width
=8) (actual time=0.004..0.004 rows=0 loops=1)
Index Cond: (user_id = 1103877)
Planning Time: 1.359 ms
Execution Time: 2453.765 ms
(23 rows)
```
After:
```
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=1.28..438.55 rows=30 width=12) (actual time=38.297..657.215 rows=30 loops=1)
-> Nested Loop Left Join (cost=1.28..195944.68 rows=13443 width=12) (actual time=38.296..657.211 rows=30 loops=1)
Filter: ((categories.topic_id <> topics.id) OR (topics.category_id = 11))
Rows Removed by Filter: 29
-> Nested Loop Left Join (cost=1.13..193462.59 rows=13443 width=16) (actual time=38.289..657.092 rows=59 loops=1)
Join Filter: (category_users.category_id = topics.category_id)
Filter: ((topics.category_id = 11) OR (COALESCE(category_users.notification_level, 1) <> 0) OR (tu.notification_level > 1))
-> Nested Loop Left Join (cost=0.85..193156.79 rows=13489 width=20) (actual time=38.282..657.059 rows=59 loops=1)
Filter: ((COALESCE(tu.notification_level, 1) > 0) AND ((topics.category_id <> 11) OR (topics.pinned_at IS NULL) OR ((topics.pinned_at <= tu.cleared_pinned_at) AND (tu.cleared_pinned_at IS NOT NULL))))
Rows Removed by Filter: 1
-> Index Scan using index_topics_on_bumped_at on topics (cost=0.42..134521.06 rows=40470 width=24) (actual time=38.267..656.850 rows=60 loops=1)
Filter: ((deleted_at IS NULL) AND ((archetype)::text <> 'private_message'::text) AND (category_id = ANY ('{11,53,57,55,54,56,112,94,107,115,116,117,97,95,102,103,101,105,99,114,106,113,104,98,100,96,108,109,110,111}'::integer[])))
Rows Removed by Filter: 569895
-> Index Scan using index_topic_users_on_topic_id_and_user_id on topic_users tu (cost=0.43..1.43 rows=1 width=16) (actual time=0.003..0.003 rows=0 loops=60)
Index Cond: ((topic_id = topics.id) AND (user_id = 1103877))
-> Materialize (cost=0.28..2.30 rows=1 width=8) (actual time=0.000..0.000 rows=0 loops=59)
-> Index Scan using index_category_users_on_user_id_and_last_seen_at on category_users (cost=0.28..2.29 rows=1 width=8) (actual time=0.004..0.004 rows=0 loops=1)
Index Cond: (user_id = 1103877)
-> Index Scan using categories_pkey on categories (cost=0.14..0.17 rows=1 width=8) (actual time=0.001..0.001 rows=1 loops=59)
Index Cond: (id = topics.category_id)
Planning Time: 1.633 ms
Execution Time: 657.255 ms
(22 rows)
```
* PERF: Optimize index on topics bumped_at.
Replace `index_topics_on_bumped_at` index with a partial index on `Topic#bumped_at` filtered by archetype since there is already another index that covers private topics.
|
||
|---|---|---|
| .devcontainer | ||
| .github | ||
| .vscode-sample | ||
| app | ||
| bin | ||
| config | ||
| db | ||
| docs | ||
| images | ||
| lib | ||
| log | ||
| plugins | ||
| public | ||
| script | ||
| spec | ||
| test | ||
| vendor | ||
| .editorconfig | ||
| .eslintignore | ||
| .eslintrc | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .licensed.yml | ||
| .npmrc | ||
| .prettierignore | ||
| .prettierrc | ||
| .rspec | ||
| .rspec_parallel | ||
| .rubocop.yml | ||
| .ruby-gemset.sample | ||
| .ruby-version.sample | ||
| .template-lintrc.js | ||
| Brewfile | ||
| CONTRIBUTING.md | ||
| COPYRIGHT.md | ||
| Gemfile | ||
| Gemfile.lock | ||
| LICENSE.txt | ||
| README.md | ||
| Rakefile | ||
| adminjs | ||
| config.ru | ||
| d | ||
| discourse.sublime-project | ||
| jsapp | ||
| lefthook.yml | ||
| package.json | ||
| translator.yml | ||
| yarn.lock | ||
README.md
Discourse is the 100% open source discussion platform built for the next decade of the Internet. Use it as a:
- mailing list
- discussion forum
- long-form chat room
To learn more about the philosophy and goals of the project, visit discourse.org.
Screenshots
Browse lots more notable Discourse instances.
Development
To get your environment setup, follow the community setup guide for your operating system.
- If you're on macOS, try the macOS development guide.
- If you're on Ubuntu, try the Ubuntu development guide.
- If you're on Windows, try the Windows 10 development guide.
If you're familiar with how Rails works and are comfortable setting up your own environment, you can also try out the Discourse Advanced Developer Guide, which is aimed primarily at Ubuntu and macOS environments.
Before you get started, ensure you have the following minimum versions: Ruby 2.7+, PostgreSQL 13+, Redis 6.0+. If you're having trouble, please see our TROUBLESHOOTING GUIDE first!
Setting up Discourse
If you want to set up a Discourse forum for production use, see our Discourse Install Guide.
If you're looking for business class hosting, see discourse.org/buy.
If you're looking for our remote work solution, see teams.discourse.com.
Requirements
Discourse is built for the next 10 years of the Internet, so our requirements are high.
Discourse supports the latest, stable releases of all major browsers and platforms:
| Browsers | Tablets | Phones |
|---|---|---|
| Apple Safari | iPadOS | iOS |
| Google Chrome | Android | Android |
| Microsoft Edge | ||
| Mozilla Firefox |
Built With
- Ruby on Rails — Our back end API is a Rails app. It responds to requests RESTfully in JSON.
- Ember.js — Our front end is an Ember.js app that communicates with the Rails API.
- PostgreSQL — Our main data store is in Postgres.
- Redis — We use Redis as a cache and for transient data.
- BrowserStack — We use BrowserStack to test on real devices and browsers.
Plus lots of Ruby Gems, a complete list of which is at /main/Gemfile.
Contributing
Discourse is 100% free and open source. We encourage and support an active, healthy community that accepts contributions from the public – including you!
Before contributing to Discourse:
- Please read the complete mission statements on discourse.org. Yes we actually believe this stuff; you should too.
- Read and sign the Electronic Discourse Forums Contribution License Agreement.
- Dig into CONTRIBUTING.MD, which covers submitting bugs, requesting new features, preparing your code for a pull request, etc.
- Always strive to collaborate with mutual respect.
- Not sure what to work on? We've got some ideas.
We look forward to seeing your pull requests!
Security
We take security very seriously at Discourse; all our code is 100% open source and peer reviewed. Please read our security guide for an overview of security measures in Discourse, or if you wish to report a security issue.
The Discourse Team
The original Discourse code contributors can be found in AUTHORS.MD. For a complete list of the many individuals that contributed to the design and implementation of Discourse, please refer to the official Discourse blog and GitHub's list of contributors.
Copyright / License
Copyright 2014 - 2021 Civilized Discourse Construction Kit, Inc.
Licensed under the GNU General Public License Version 2.0 (or later); you may not use this work except in compliance with the License. You may obtain a copy of the License in the LICENSE file, or at:
https://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
Discourse logo and “Discourse Forum” ®, Civilized Discourse Construction Kit, Inc.
Dedication
Discourse is built with love, Internet style.