Rattail

This is closely related to #6.

While it's possible to increase the DB pool size used for datasync via config, it apparently also is possible to hit the max connection limit imposed by PostgreSQL itself. When this happens you'll see an error like:

OperationalError: (psycopg2.OperationalError) FATAL:  remaining connection slots are reserved for non-replication superuser connections

(Background on this error at: http://sqlalche.me/e/13/e3q8)

There are a couple of Stack Overflow questions about this:

• https://stackoverflow.com/questions/11847144/heroku-psql-fatal-remaining-connection-slots-are-reserved-for-non-replication
• https://stackoverflow.com/questions/52697734/postgresql-remaining-connection-slots-are-reserved-for-non-replication-superus

Basically the options are to increase max connection limit in PostgreSQL config, or else reduce the number of actual connections being requested (i.e. by datasync). The latter would be nice but as with #6 for now the quickest fix is probably to increase limit in PG.

Do that by editing e.g. /etc/postgresql/13/main/postgresql.conf to set:

max_connections = 200

See also docs for that setting. Be sure to restart PostgreSQL after updating its config.