module PgsqlStats
  class Sequence
    attr_accessor :oid, :name, :schema_name, :blocks_read, :cache_hits
    
    def initialize(connection, row)
      @connection = connection
      load(row)
    end
    
    def refresh
      load(@connection.select_one("SELECT * FROM pg_statio_all_sequences WHERE relid = #{oid}"))
    end
    
    def cache_hit_rate
      cache_hits.to_f / (blocks_read + cache_hits) * 100
    end
    
    private
    
    def load(row)
      self.oid = row["relid"].to_i
      self.name = row["relname"]
      self.schema_name = row["schemaname"]
      self.blocks_read = row["blks_read"].to_i
      self.cache_hits = row["blks_hit"].to_i
    end
  end
end