CREATE UNIQUE INDEX tag_u ON tag (usort(tag));

CREATE INDEX tag_g ON tag USING gin (tag);

-- table to hold tag - site links
CREATE TABLE urls (
	date_added timestamp without time zone DEFAULT ('now'::text)::timestamp(0) without time zone NOT NULL,
	id_site smallint NOT NULL,
	id_tag smallint NOT NULL,
	regexp text
);

CREATE UNIQUE INDEX urls_pkey ON urls USING btree (id_site, regexp);

CREATE INDEX urls_id_tag ON urls USING btree (id_tag);