NAME

       srf_index_hash - Adds a hash-table index to an SRF file.

SYNOPSIS

       srf_index_hash  [-c] srf_archive

DESCRIPTION

       srf_index_hash adds and index to an SRF file or replaces an existing index with a new one.
       In the case of concatenated SRF files only the  index  at  the  end  of  a  file  will  be
       replaced, but internal indices will not be consulted by SRF tools.

       The  index  is  a  hash  table  indexing the sequence names only. The name itself does not
       appear in the index, rather the top 7-bits of a 64-bit hash key  are  held  in  the  index
       along with N-bits used to determine the hash bucket. This reduces the index size to around
       10-15 bytes per sequence.

OPTIONS

       -c     Check only. This requests that the index is not produced, but the checks  performed
              during  the creation of an index (such as looking for duplicate sequence names) are
              still performed.

AUTHOR

       James Bonfield, Wellcome Trust Sanger Institute

                                           September 29                         srf_index_hash(1)