Improving the Access Time for Random Access Files
Clustering in the key set is decreased by
smoothing the key-to-address transformation, and 
by adding shadow buckets to an open chaining file.  The
keys are pre-hashed before the address division, 
to remove the effect of sequential properties in the
key set.  Shadow buckets in the key search sequence 
reduce the effect of nonuniformity in file loading,
and decrease the number of maximum probes needed 
to locate a record.  The combined effects of these techniques
lead to improved file performance for secondary 
storage devices, as shown by empirical studies.
CACM March, 1977
Clapson, P.
