server-configs/shared/applications/server/postgresql.nix

{ config, ... }:

{
  services.postgresql = {
    enable = true;
  };

  # backup postgresql databases (everything in ensuredatabases)
  services.postgresqlBackup = {
    enable = true;

    compression = "zstd";

    # default to backup all databases
    databases = config.services.postgresql.ensureDatabases;
  };

  # default the locale to C. I have NO CLUE why you would
  # like to use any other locale, than the default C.
  # However, matrix synapse complains A LOT if it isn't C,
  # so we just default to it! No worries!
  # Matrix Synapse Locale Note
  #   - https://github.com/element-hq/synapse/blob/develop/docs/postgres.md#fixing-incorrect-collate-or-ctype
  # NOTE from postgresql here https://www.postgresql.org/docs/current/locale.html
  # Using C.UTF-8, because setting `LC_CTYPE=C` will default encoding to SQL_ASCII.
  # https://pganalyze.com/blog/5mins-postgres-17-builtin-c-utf8-locale
  systemd.services.postgresql.environment = {
    LC_CTYPE = "C.UTF-8";
    LC_COLLATE = "C";
  };
}