Zulip supports full-text search, which can be combined arbitrarily with Zulip’s full suite of narrowing operators. By default, it only supports English text, but there is an experimental PGroonga integration that provides full-text search for all languages.
The user interface and feature set for Zulip’s full-text search is documented in the “Search help” documentation section in the Zulip app’s gear menu.
The default full-text search implementation¶
Zulip’s uses PostgreSQL’s built-in full-text search feature, with a custom set of English stop words to improve the quality of the search results.
We use a small extension, tsearch_extras, for highlighting of the matching words. There is some discussion of removing this extension, at least as an option, so that Zulip can be used with database-as-a-service platforms.
In order to optimize the performance of delivering messages, the
full-text search index is updated for newly sent messages in the
background, after the message has been delivered. This background
updating is done by
puppet/zulip/files/postgresql/process_fts_updates, which is usually
deployed on the database server, but could be deployed on an
application server instead.