This blog post by Victor Berger explains how to use many of the tools listed on this page: https://levans.fr/shrink-synapse-database.html

# List of useful tools and scripts for maintenance Synapse database:

## Purge Remote Media API

The purge remote media API allows server admins to purge old cached remote media.

## Purge Local Media API

This API deletes the local media from the disk of your own server.

## Purge History API

The purge history API allows server admins to purge historic events from their database, reclaiming disk space.

## synapse-compress-state

Tool for compressing (deduplicating) `state_groups_state` table.

## SQL for analyzing Synapse PostgreSQL database stats

Some easy SQL that reports useful stats about your Synapse database.