Date:         Sat, 18 Mar 1995 13:54:01 EST
Reply-To:     The NOMAD2 Discussion List
Sender:       The NOMAD2 Discussion List
From:         Dave Tracy
Organization: Yale University C&IS
Subject:      reading backward

 Hi all,
        I have a master with 3 keys, key 1 is 099, key 2 is
        a4 and key 3 is datetime. I am trying to match key 1
        key 2 and +- 2 minutes on the datetime field to
        an external file. Problem is I have to read file
        backward. I have tried selecting each pass through
        on ge  min(datetime) and max(datetime). Then I use
        last and move backward using previous. It works
        but very poor performance when I issue the last command.
        Also poor performance  on the first previous command.
        Selects are on keys: select xxx=key1, select xxx = key2,
        select xxx le max datetime; Any help would be appreciated.
                               Thanks in advance...
                                           ..Dave Tracy
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