A method, apparatus, software and data structure is disclosed for more efficient
access times for linear operations in a hash table, including finding the nearest
logical record. A plurality of actual data records and a plurality of marker data
records are inserted in a hash table using a hash function. The actual data records
and marker data records have a logical ordering specified by a key and are threaded
into the hash table to allow linear access by walking the hash table. The logical
ordering of the actual data records and marker records is lost upon entry into
the hash table, and the keys of the marker data records are distributed at known
positions throughout the range of the keys of the actual data records. If when
hashing a given key no record exists in the database for the given key, one of
the keys for the marker data records are hashed to locate the associated marker
data record in the hash table. A nearest logical record may thus be retrieved entering
the hash table through the marker data record.