50 lines
		
	
	
		
			2.3 KiB
		
	
	
	
		
			Markdown
		
	
	
			
		
		
	
	
			50 lines
		
	
	
		
			2.3 KiB
		
	
	
	
		
			Markdown
		
	
	
User Directory API Implementation
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=================================
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The user directory is currently maintained based on the 'visible' users
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on this particular server - i.e. ones which your account shares a room with, or
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who are present in a publicly viewable room present on the server.
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The directory info is stored in various tables, which can (typically after
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DB corruption) get stale or out of sync. If this happens, for now the
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solution to fix it is to use the [admin API](usage/administration/admin_api/background_updates.md#run)
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and execute the job `regenerate_directory`. This should then start a background task to
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flush the current tables and regenerate the directory.
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Data model
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----------
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There are five relevant tables that collectively form the "user directory".
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Three of them track a master list of all the users we could search for.
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The last two (collectively called the "search tables") track who can
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see who.
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From all of these tables we exclude three types of local user:
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  - support users
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  - appservice users
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  - deactivated users
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* `user_directory`. This contains the user_id, display name and avatar we'll
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  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
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    ever put publicly visible names here. Otherwise we might leak a private
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    nickname or avatar used in a private room.
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  - Indexed on rooms. Indexed on users.
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* `user_directory_search`. To be joined to `user_directory`. It contains an extra
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  column that enables full text search based on user ids and display names.
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  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
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  the directory is complete, we record a stream position here. This indicates
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  that synapse should now listen for room changes and incrementally update
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  the directory where necessary.
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* `users_in_public_rooms`. Contains associations between users and the public rooms they're in.
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  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`
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   is a local user and `M` is a local or remote user. `L` and `M` should be
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   different, but this isn't enforced by a constraint.
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