George Young wrote:
...
  >I need to produce a new table that coalesces immediately successive
  >operations on a run into one, e.g.:
  >
  >run   |  start               | done
  >  1415|  2001-01-29 12:36:55| 2001-02-07 13:02:38
  >  1415|  2001-02-14 07:40:04|
  >  1747|  2001-02-15 09:14:39| 2001-03-01 09:02:39
  >  1747|  2001-03-05 13:13:58|  
  >  1954|  2001-02-02 20:55:39| 2001-03-02 10:17:15
  >
  >i.e. where a run has one or more steps with succesive seq values,
  >or equivalently, with abutting start/end values, then I want
  >the new table to have only one entry representing the full span of
  >time.  Null 'done' just means it's not done yet.  
...
  >Can anyone think of a way I can do this in postgres?
 
I think you would be better off feeding the log out of the database into
a perl script.  SQL is a set-oriented language that can't do this
sort of thing without some appalling contortions, if at all.  (I can't
think of a way to do it.) So, store the data in PostgreSQL, but do
procedural processing in a more appropriate language.

-- 
Oliver Elphick                                [EMAIL PROTECTED]
Isle of Wight                              http://www.lfix.co.uk/oliver
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                 ========================================
     "Let your light so shine before men, that they may see 
      your good works, and glorify your Father which is in 
      heaven."         Matthew 5:16 



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