Question

I have a site which needs one admin-editable integer. It has no association to any other model or attribute in the database. It’s literally a flat integer, between 1-10,000, that the admin (who is the only user) needs access to edit.

My question relates to database design. Surely the most efficient way to do this isn’t to create its own table, with just one single column and one single row?

In short…one single field, no associations: how should I best roll that?

Answer 1

It depends on how you define “efficient”.

If you define “efficient” as using

• a single storage mechanism for all user-editable data (a database),
• a single security mechanism for all user-editable data (SQL GRANT and REVOKE), and
• a single constraint mechanism for all user-editable data (SQL DDL),

then creating a one-row table probably is the most efficient. Something along these lines might work on the database side.

create table admin_editable_integer (
  restrictive_key integer primary key,
  the_integer integer not null,
  -- Allow only one row.
  check (restrictive_key = 1),
  -- Restrict the range of integers.
  check (the_integer between 1 and 10000)
);

revoke all on admin_editable_integer from public;
grant select, insert, update on admin_editable_integer to admin;

I don’t think rails supports CHECK constraints, so I think you’ll need to pass ALTER TABLE SQL statements in the migration.