   FOREIGN KEY (synteny_region_id) REFERENCES synteny_region(synteny_region_id),
   FOREIGN KEY (dnafrag_id) REFERENCES dnafrag(dnafrag_id),
 
+	-- NO PK: would need to do (synteny_region_id,dnafrag_id,dnafrag_start)
+
   KEY synteny (synteny_region_id,dnafrag_id),
   KEY synteny_reversed (dnafrag_id,synteny_region_id)
 


  FOREIGN KEY (node_id) REFERENCES gene_tree_node(node_id),

  KEY node_id_tag (node_id, tag),
  KEY tag (tag)


  FOREIGN KEY (dnafrag_id) REFERENCES dnafrag(dnafrag_id),
  FOREIGN KEY (method_link_species_set_id) REFERENCES method_link_species_set(method_link_species_set_id),

	-- NO PK. this table is voluntarily denormalized.

  KEY constrained_element_id_idx (constrained_element_id),
  KEY mlssid_idx (method_link_species_set_id),
  KEY mlssid_dfId_dfStart_dfEnd_idx (method_link_species_set_id,dnafrag_id,dnafrag_start,dnafrag_end),
