def otu_query_facet
        return nil if otu_query.nil?
        s = 'WITH query_otu_ces AS (' + otu_query.all.to_sql + ') ' +
          ::CollectingEvent.joins(:otus)
          .joins('JOIN query_otu_ces as query_otu_ces1 on query_otu_ces1.id = otus.id')