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User Directory API Implementation

The user directory is currently maintained based on the 'visible' users +on this particular server - i.e. ones which your account shares a room with, or +who are present in a publicly viewable room present on the server.

The directory info is stored in various tables, which can (typically after +DB corruption) get stale or out of sync. If this happens, for now the +solution to fix it is to use the admin API +and execute the job regenerate_directory. This should then start a background task to +flush the current tables and regenerate the directory.

Data model

There are five relevant tables that collectively form the "user directory". +Three of them track a master list of all the users we could search for. +The last two (collectively called the "search tables") track who can +see who.

From all of these tables we exclude three types of local user:

support users
appservice users
deactivated users

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user_directory. This contains the user_id, display name and avatar we'll +return when you search the directory.
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- Because there's only one directory entry per user, it's important that we only +ever put publicly visible names here. Otherwise we might leak a private +nickname or avatar used in a private room.
- Indexed on rooms. Indexed on users.
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user_directory_search. To be joined to user_directory. It contains an extra +column that enables full text search based on user ids and display names. +Different schemas for SQLite and Postgres with different code paths to match.
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- Indexed on the full text search data. Indexed on users.
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user_directory_stream_pos. When the initial background update to populate +the directory is complete, we record a stream position here. This indicates +that synapse should now listen for room changes and incrementally update +the directory where necessary.
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users_in_public_rooms. Contains associations between users and the public rooms they're in. +Used to determine which users are in public rooms and should be publicly visible in the directory.
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users_who_share_private_rooms. Rows are triples (L, M, room id) where L +is a local user and M is a local or remote user. L and M should be +different, but this isn't enforced by a constraint.
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Synapse

User Directory API Implementation

Data model