Re: need to join successive log entries into one

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 Oliver(dot)Elphick(at)lfix(dot)co(dot)uk
Isle of Wight http://www.lfix.co.uk/oliver
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