Edith Cohen Nick G. Duffield Haim Kaplan Carsten Lund Mikkel Thorup Composable, Scalable, and Accurate Weight Summarization of Unaggregated Data Sets. 431-442 2009 2 PVLDB 1 http://www.vldb.org/pvldb/2/vldb09-85.pdf db/journals/pvldb/pvldb2.html#CohenDKLT09