PostgreSQL Tuning

See https://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server

Referenced from https://matrix-org.github.io/synapse/latest/postgres.html#tuning-postgres

we've found tuning the following values helpful for performance:

• shared_buffers
• effective_cache_size
• work_mem
• maintenance_work_mem
• autovacuum_work_mem

Note that the appropriate values for those fields depend on the amount of free memory the database host has available.