898b71da88
Why this change? There are two problematic queries in question here when loading notifications in various tabs in the user menu: ``` SELECT "notifications".* FROM "notifications" LEFT JOIN topics ON notifications.topic_id = topics.id WHERE "notifications"."user_id" = 1338 AND (topics.id IS NULL OR topics.deleted_at IS NULL) ORDER BY notifications.high_priority AND NOT notifications.read DESC, NOT notifications.read AND notifications.notification_type NOT IN (5,19,25) DESC, notifications.created_at DESC LIMIT 30; ``` and ``` EXPLAIN ANALYZE SELECT "notifications".* FROM "notifications" LEFT JOIN topics ON notifications.topic_id = topics.id WHERE "notifications"."user_id" = 1338 AND (topics.id IS NULL OR topics.deleted_at IS NULL) AND "notifications"."notification_type" IN (5, 19, 25) ORDER BY notifications.high_priority AND NOT notifications.read DESC, NOT notifications.read DESC, notifications.created_at DESC LIMIT 30; ``` For a particular user, the queries takes about 40ms and 26ms respectively on one of our production instance where the user has 10K notifications while the site has 600K notifications in total. What does this change do? 1. Adds the `index_notifications_user_menu_ordering` index to the `notifications` table which is indexed on `(user_id, (high_priority AND NOT read) DESC, (NOT read) DESC, created_at DESC)`. 1. Adds a second index `index_notifications_user_menu_ordering_deprioritized_likes` to the `notifications` table which is indexed on `(user_id, (high_priority AND NOT read) DESC, (NOT read AND notification_type NOT IN (5,19,25)) DESC, created_at DESC)`. Note that we have to hardcode the like typed notifications type here as it is being used in an ordering clause. With the two indexes above, both queries complete in roughly 0.2ms. While I acknowledge that there will be some overhead in insert,update or delete operations. I believe this trade-off is worth it since viewing notifications in the user menu is something that is at the core of using a Discourse forum so we should optimise this experience as much as possible. |
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README.md
Discourse is the online home for your community. We offer a 100% open source community platform to those who want complete control over how and where their site is run.
Our platform has been battle-tested for over a decade and continues to evolve to meet users’ needs for a powerful community platform. Discourse allows you to create discussion topics and connect using real-time chat, as well as access an ever-growing number of official and community themes. In addition, we offer a wide variety of plugins for features ranging from chatbots powered by Discourse AI to functionalities like SQL analysis using the Data Explorer plugin.
To learn more, visit discourse.org and join our support community at meta.discourse.org.
Screenshots
Browse lots more notable Discourse instances.
Development
To get your environment set up, 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 looking to use a simpler Docker-based install, try the Docker 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 3.2+, PostgreSQL 13, Redis 7. If you're having trouble, please see our TROUBLESHOOTING GUIDE first!
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Discourse is built for the next 10 years of the Internet, so our requirements are high.
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Before contributing to Discourse:
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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.
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Copyright 2014 - 2023 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:
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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.
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To guide our ongoing effort to build accessible software we follow the W3C’s Web Content Accessibility Guidelines (WCAG). If you'd like to report an accessibility issue that makes it difficult for you to use Discourse, email accessibility@discourse.org. For more information visit discourse.org/accessibility.
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