A bloom filter is generated for efficient query processing for unsorted data in a column of a columnar database. Bloom filters represented as bitmaps are generated for data blocks storing data for a column of a columnar database table. An indication of a query directed toward the column is received and the bloom filter for each data block is examined to determine which ones of the data blocks do not need to be read in order to service the query for the select data. Data is then read from the data blocks storing data for the column excepting the ones which do not need to be read.