Extreme value computation

A computer program product for storing a data table, wherein the data table has at least one attribute, and wherein a first data block of the data table comprises a set of data rows of the data table, and wherein a current data block being the first data block, the computer program product comprising:

• one or more non-transitory computer-readable tangible storage media and program instructions stored on at least one of the one or more non-transitory tangible storage media, the program instructions executable by a processor, the program instructions comprising:
• program instructions to provide a plurality of synopsis techniques for determining a plurality of attribute value information indicative of the at least one attribute;
• program instructions to determine a data characteristic describing the plurality of data rows of the current data block;
• program instructions to select, based on the determined data characteristic, at least one synopsis technique of the provided plurality of synopsis techniques suitable for generating the plurality of attribute value information for the at least one attribute of the current data block;
• program instructions to determine the plurality of attribute value information for the at least one attribute of the plurality of data rows of the current data block using the at least one selected synopsis technique, wherein determining the plurality of attribute value information further comprises:
• scanning the current data block to identify a fixed number j from a plurality of first distinct values of the at least one attribute for indicating a value range of the at least one attribute in the current data block;
• dividing the value range into a plurality of sub-ranges;
• and
• creating a distribution of a plurality of buckets, wherein each bucket is associated with a respective sub-range of the plurality of sub-ranges;
• program instructions to store the determined plurality of attribute value information for the current data block to be used for query processing against the data table;
• further scanning the current data block;
• determining a bucket within the plurality of buckets is available for each further current value j+1 of the at least one attribute;
• marking the bucket as a non-empty bucket;
• providing the plurality of attribute value information as comprising a plurality of extremum values of the at least one attribute in the current data block, the distribution of the plurality of buckets, and the value range in each of the distribution of the plurality of buckets;
• receiving a query of the at least one attribute of the data table;
• determining a plurality of empty buckets within the distribution of the plurality of buckets;
• comparing the determined plurality of empty buckets with a predetermined maximum number;
• and
• using one of the distribution of the plurality of buckets and the plurality of extremum values to decide to scan or not to scan the current data block for evaluating the received query based on the compared plurality of empty buckets.