mirror of
https://github.com/element-hq/synapse.git
synced 2024-12-21 12:14:29 +03:00
0fd6b269d3
### Pull Request Checklist <!-- Please read https://element-hq.github.io/synapse/latest/development/contributing_guide.html before submitting your pull request --> * [X] Pull request is based on the develop branch * [X] Pull request includes a [changelog file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog). The entry should: - Be a short description of your change which makes sense to users. "Fixed a bug that prevented receiving messages from other servers." instead of "Moved X method from `EventStore` to `EventWorkerStore`.". - Use markdown where necessary, mostly for `code blocks`. - End with either a period (.) or an exclamation mark (!). - Start with a capital letter. - Feel free to credit yourself, by adding a sentence "Contributed by @github_username." or "Contributed by [Your Name]." to the end of the entry. * [X] [Code style](https://element-hq.github.io/synapse/latest/code_style.html) is correct (run the [linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))
133 lines
6.4 KiB
Markdown
133 lines
6.4 KiB
Markdown
# User Directory API Implementation
|
|
|
|
The user directory is maintained based on users that are 'visible' to the homeserver -
|
|
i.e. ones which are local to the server and ones which any local user shares a
|
|
room with.
|
|
|
|
The directory info is stored in various tables, which can sometimes get out of
|
|
sync (although this is considered a bug). If this happens, for now the
|
|
solution to fix it is to use the [admin API](usage/administration/admin_api/background_updates.md#run)
|
|
and execute the job `regenerate_directory`. This should then start a background task to
|
|
flush the current tables and regenerate the directory. Depending on the size
|
|
of your homeserver (number of users and rooms) this can take a while.
|
|
|
|
## Data model
|
|
|
|
There are five relevant tables that collectively form the "user directory".
|
|
Three of them track a list of all known users. The last two (collectively called
|
|
the "search tables") track which users are visible to each other.
|
|
|
|
From all of these tables we exclude three types of local user:
|
|
|
|
- support users
|
|
- appservice users
|
|
- deactivated users
|
|
|
|
A description of each table follows:
|
|
|
|
* `user_directory`. This contains the user ID, display name and avatar of each user.
|
|
- Because there is only one directory entry per user, it is important that it
|
|
only contain publicly visible information. Otherwise, this will leak the
|
|
nickname or avatar used in a private room.
|
|
- Indexed on rooms. Indexed on users.
|
|
|
|
* `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 are used.
|
|
- Indexed on the full text search data. Indexed on users.
|
|
|
|
* `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. (See [stream positions](development/synapse_architecture/streams.html).)
|
|
|
|
* `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. Both local and remote users are tracked.
|
|
|
|
* `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.
|
|
|
|
Note that if two local users share a room then there will be two entries:
|
|
`(user1, user2, !room_id)` and `(user2, user1, !room_id)`.
|
|
|
|
## Configuration options
|
|
|
|
The exact way user search works can be tweaked via some server-level
|
|
[configuration options](usage/configuration/config_documentation.md#user_directory).
|
|
|
|
The information is not repeated here, but the options are mentioned below.
|
|
|
|
## Search algorithm
|
|
|
|
If `search_all_users` is `false`, then results are limited to users who:
|
|
|
|
1. Are found in the `users_in_public_rooms` table, or
|
|
2. Are found in the `users_who_share_private_rooms` where `L` is the requesting
|
|
user and `M` is the search result.
|
|
|
|
Otherwise, if `search_all_users` is `true`, no such limits are placed and all
|
|
users known to the server (matching the search query) will be returned.
|
|
|
|
By default, locked users are not returned. If `show_locked_users` is `true` then
|
|
no filtering on the locked status of a user is done.
|
|
|
|
The user provided search term is lowercased and normalized using [NFKC](https://en.wikipedia.org/wiki/Unicode_equivalence#Normalization),
|
|
this treats the string as case-insensitive, canonicalizes different forms of the
|
|
same text, and maps some "roughly equivalent" characters together.
|
|
|
|
The search term is then split into words:
|
|
|
|
* If [ICU](https://en.wikipedia.org/wiki/International_Components_for_Unicode) is
|
|
available, then the system's [default locale](https://unicode-org.github.io/icu/userguide/locale/#default-locales)
|
|
will be used to break the search term into words. (See the
|
|
[installation instructions](setup/installation.md) for how to install ICU.)
|
|
* If unavailable, then runs of ASCII characters, numbers, underscores, and hyphens
|
|
are considered words.
|
|
|
|
The queries for PostgreSQL and SQLite are detailed below, but their overall goal
|
|
is to find matching users, preferring users who are "real" (e.g. not bots,
|
|
not deactivated). It is assumed that real users will have a display name and
|
|
avatar set.
|
|
|
|
### PostgreSQL
|
|
|
|
The above words are then transformed into two queries:
|
|
|
|
1. "exact" which matches the parsed words exactly (using [`to_tsquery`](https://www.postgresql.org/docs/current/textsearch-controls.html#TEXTSEARCH-PARSING-QUERIES));
|
|
2. "prefix" which matches the parsed words as prefixes (using `to_tsquery`).
|
|
|
|
Results are composed of all rows in the `user_directory_search` table whose information
|
|
matches one (or both) of these queries. Results are ordered by calculating a weighted
|
|
score for each result, higher scores are returned first:
|
|
|
|
* 4x if a user ID exists.
|
|
* 1.2x if the user has a display name set.
|
|
* 1.2x if the user has an avatar set.
|
|
* 0x-3x by the full text search results using the [`ts_rank_cd` function](https://www.postgresql.org/docs/current/textsearch-controls.html#TEXTSEARCH-RANKING)
|
|
against the "exact" search query; this has four variables with the following weightings:
|
|
* `D`: 0.1 for the user ID's domain
|
|
* `C`: 0.1 for unused
|
|
* `B`: 0.9 for the user's display name (or an empty string if it is not set)
|
|
* `A`: 0.1 for the user ID's localpart
|
|
* 0x-1x by the full text search results using the `ts_rank_cd` function against the
|
|
"prefix" search query. (Using the same weightings as above.)
|
|
* If `prefer_local_users` is `true`, then 2x if the user is local to the homeserver.
|
|
|
|
Note that `ts_rank_cd` returns a weight between 0 and 1. The initial weighting of
|
|
all results is 1.
|
|
|
|
### SQLite
|
|
|
|
Results are composed of all rows in the `user_directory_search` whose information
|
|
matches the query. Results are ordered by the following information, with each
|
|
subsequent column used as a tiebreaker, for each result:
|
|
|
|
1. By the [`rank`](https://www.sqlite.org/windowfunctions.html#built_in_window_functions)
|
|
of the full text search results using the [`matchinfo` function](https://www.sqlite.org/fts3.html#matchinfo). Higher
|
|
ranks are returned first.
|
|
2. If `prefer_local_users` is `true`, then users local to the homeserver are
|
|
returned first.
|
|
3. Users with a display name set are returned first.
|
|
4. Users with an avatar set are returned first.
|