 -- connected components of the annotation graph
 -- are of a type: Coverage, Dominance, Pointing relation or NULL for root nodes
 -- have a name
+DROP TABLE IF EXISTS _component;
 CREATE TABLE _component
 (
 	id			numeric(38) NOT NULL,		-- primary key

-- pre and post order of the annotation graph
-- root nodes: parent IS NULL
-- component and rank together model edges in the annotation graph
CREATE TABLE _rank
(
	pre				numeric(38)	NOT NULL,	-- pre and post order of the annotation ODAG


-- corpus annotations
-- unique combinantion of corpus_ref, namespace and name
DROP TABLE IF EXISTS _corpus_annotation;
CREATE TABLE _corpus_annotation
(
	corpus_ref	numeric(38) NOT NULL,		-- foreign key to _corpus.id
