create table ns (
    prefix char(16),
    uri char(255)
);

create table node (
    id serial primary key,
    created timestamp,
    value text,
    is_resource integer
);

create table statement (
    id serial primary key,
    created timestamp,
    subject integer,
    predicate integer,
    object integer,
    context integer
);

create index subject on statement (subject);
create index predicate on statement (predicate);
create index object on statement (object);
create index context on statement (context);