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From: larsi@ifi.uio.no (Lars Magne Ingebrigtsen)
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Subject: Re: reading .overview files takes too long!
Date: 02 Nov 1995 04:40:50 +0100
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Per Abrahamsen <abraham@dina.kvl.dk> writes:

> LMI> But `sort-by-date' is (and will always be) very slow,
> 
> It does parse the date header O(N log N) times, and only need to do
> that O(N) times, so it can be made much faster.

That's true.  That would require a slight total rewrite of the thread
sorting functions, though.  

But the number of threads in a typical group usually is seldom over
100, which means that the time saved might be lost in the extra
overhead...  but probably not.

Yikes!  This is `gnus-sortable-date', which is called twice for each
comparison (O(N log N)):

(defun gnus-sortable-date (date)
  "Make sortable string by string-lessp from DATE.
Timezone package is used."
  (let* ((date (timezone-fix-time date nil nil)) ;[Y M D H M S]
	 (year (aref date 0))
	 (month (aref date 1))
	 (day (aref date 2)))
    (timezone-make-sortable-date 
     year month day 
     (timezone-make-time-string
      (aref date 3) (aref date 4) (aref date 5)))))

I think I'll stick by my original statement -- `sort-by-date' will
always be slow.  :-)

-- 
Home is where the cat is.