the present invention is directed to a system , method and computer readable medium for estimating a column cardinality value for a column in a partitioned table stored in a plurality of nodes in a relational database . according to one embodiment of the present invention , a plurality of column values for the partitioned table stored in each node are hashed , and a hash data set for each node is generated . each of the hash data sets from each node is transferred to a coordinator node designated from the plurality of nodes . the hash data sets are merged into a merged data set , and an estimated column cardinality value for the table is calculated from the merged data set .