Databases Theory and Applications 30th Australasian Database Conference, ADC 2019, Sydney, NSW, Australia, January 29 - February 1, 2019, Proceedings - Chang, Lijun; Chang, Lijun; Gan, Junhao; Gan, Junhao; Cao, Xin; Cao, Xin (Springer International Publishing : Imprint: Springer, 2019)