create table fixer_rates_success_responses (
  success boolean not null,
  base text references currencies not null,
  rates ,
  timestamp bigint not null
);
comment on table fixer_rates_success_responses is '
  fixer.io response for exchange rate between two currencies
';

comment on column fixer_rates_success_responses.success is '
  response status, should be true in this case
';
comment on column fixer_rates_success_responses.base is '
  base currency
';
comment on column fixer_rates_success_responses.rates is '
  target currencies
';
comment on column fixer_rates_success_responses.timestamp is '
  epoch timestamp of returned exchange rate
';