Abstract: A method and system for performing a scan operation on a table of a column-oriented database is described. One embodiment receives a database query that references a particular column in a table, the particular column being horizontally partitioned into at least one extent, the at least one extent including at least one data block; consults, for each extent in the particular column for which associated metadata is available, the metadata associated with that extent to determine whether that extent is required to process the scan operation; acquires, for each extent in the particular column for which associated metadata is not available, metadata associated with that extent and uses the acquired metadata associated with that extent to determine whether that extent is required to process the scan operation; and performs the scan operation on only those extents in the particular column determined to be required to process the scan operation.