LetKbearight-continuousandnondecreasingfunction.AfunctionfanalyticintheunitdiskDbelongstothespaceDKifD|f(z)|2K(1-|z|2)dA(z)<∞.DecompositiontheoremsforDKspacesareestablishedinthispaper.Asanapplication,weobtainacharacterizationofinterpolationbyfunctionsinDKspaces.Furthermore,wecharacterizefunctionsinDKspacesbyconjugatepairs.