Matrix Synapse

PostgreSQL

List databases

psql --u admin_user --list

Vacuum (clean up) a database

vacuumdb --u admin_user db_name

Media

Delete media older than X days

This might delete avatars and other old files that are actively used.

find /var/lib/matrix-synapse/media/ -mtime -365 -delete

Links about cleaning up the DB

Compressing Synapse database
About state_groups_state