But if one is going to use a key-value store anyway, where is the "mangling"? Building a key-value store in an SQL database is trivial (this below is for PostgreSQL):

    create table keyvalue (key text, value text);
    create index keyvalue_idx on keyvalue(key);

And use is trivial as well:

    insert into keyvalue (key, value) values ('key', 'value');

    select value from keyvalue where key = 'key';

[edit] formatting fix.