b555d3f553
The query plan for fetching recent messages from the arbitrary set of streams formed by the intersection of 30 random users can be quite bad, and can descend into a sequential scan on `zerver_recipient`. Worse, this work of pulling recent messages out is redone if the stream appears in the next batch of 30 users. Instead, pull the recent messages for a stream on a one-by-one basis, but cache them in an in-memory cache. Since digests are enqueued in 30-user batches but still one-realm-at-a-time, work will be saved both in terms of faster query plans whose results can also be reused across batches. This requires that we pull the stream-id to stream-name mapping for _all_ streams in the realm at once, but that is well-indexed and unlikely to cause performance issues -- in fact, it may be faster than pulling a random subset of the streams in the realm.
Zulip overview
Zulip is an open-source team collaboration tool with unique topic-based threading that combines the best of email and chat to make remote work productive and delightful. Fortune 500 companies, leading open source projects, and thousands of other organizations use Zulip every day. Zulip is the only modern team chat app that is designed for both live and asynchronous conversations.
Zulip is built by a distributed community of developers from all around the world, with 74+ people who have each contributed 100+ commits. With over 1000 contributors merging over 500 commits a month, Zulip is the largest and fastest growing open source team chat project.
Come find us on the development community chat!
Getting started
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Contributing code. Check out our guide for new contributors to get started. We have invested in making Zulip’s code highly readable, thoughtfully tested, and easy to modify. Beyond that, we have written an extraordinary 150K words of documentation for Zulip contributors.
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Contributing non-code. Report an issue, translate Zulip into your language, or give us feedback. We'd love to hear from you, whether you've been using Zulip for years, or are just trying it out for the first time.
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Checking Zulip out. The best way to see Zulip in action is to drop by the Zulip community server. We also recommend reading about Zulip's unique approach to organizing conversations.
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Running a Zulip server. Self-host Zulip directly on Ubuntu or Debian Linux, in Docker, or with prebuilt images for Digital Ocean and Render. Learn more about self-hosting Zulip.
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Using Zulip without setting up a server. Learn about Zulip Cloud hosting options. Zulip sponsors free Zulip Cloud Standard for hundreds of worthy organizations, including fellow open-source projects.
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Participating in outreach programs like Google Summer of Code and Outreachy.
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Zulip is distributed under the Apache 2.0 license.