 	query integer references queries(id) ON DELETE CASCADE,
 	word varchar(255) not null,
 	pos varchar(255) not null,
-	sense varchar(255) default null,
+	sense varchar(255) default '',
 	synonyms varchar(255)[] default '{}',
 	primary key (query, word, pos, sense),
 	constraint word_pos unique(word, pos)

	source integer not null references sources(id) ON DELETE CASCADE,
	url text unique not null,
	filename text default null,
	keywords text[] default null
);

CREATE TABLE IF NOT EXISTS users (

CREATE TABLE IF NOT EXISTS query_articles (
	query integer references queries(id) ON DELETE CASCADE,
	article integer references articles(id) ON DELETE CASCADE,
	accuracy real default 0.0,
	processed boolean default false,
	primary key (query, article)
);
