This needs to be published...
On Wed, Nov 4, 2009 at 4:18 PM, marcin mank <marcin.mank@gmail.com> wrote:
>> I think the Oracle guy's version could easily be adapted to PG 8.4 ---
>> those little rownum subqueries seem to be just a substitute for not
>> having generate_series(1,9), and everything else is just string-pushing.
>
> indeed.
>
> marcin=# with recursive x( s, ind ) as
> ( select sud, position( ' ' in sud )
> from (select '53 7 6 195 98 6 8 6 34 8 3 17 2
> 6 6 28 419 5 8 79'::text as sud) xx
> union all
> select substr( s, 1, ind - 1 ) || z || substr( s, ind + 1 )
> , position(' ' in repeat('x',ind) || substr( s, ind + 1 ) )
> from x
> , (select gs::text as z from generate_series(1,9) gs)z
> where ind > 0
> and not exists ( select null
> from generate_series(1,9) lp
> where z.z = substr( s, ( (ind - 1 ) / 9 ) * 9 + lp, 1 )
> or z.z = substr( s, mod( ind - 1, 9 ) - 8 + lp * 9, 1 )
> or z.z = substr( s, mod( ( ( ind - 1 ) / 3 ), 3 ) * 3
> + ( ( ind - 1 ) / 27 ) * 27 + lp
> + ( ( lp - 1 ) / 3 ) * 6
> , 1 )
> )
> )
> select s
> from x
> where ind = 0;
> s
> -----------------------------------------------------------------------------------
> 534678912672195348198342567859761423426853791713924856961537284287419635345286179
> (1 row)
>
> Time: 472.027 ms
>
>
> btw: it is pretty cool to replace some of the numbers in input with
> spaces and see how the query finds multiple solutions
>
> btw2: is SQL with 'with recursive' turing-complete ? Anyone care to
> try a Brainf*ck interpreter ? :)
>
> Greetings
> marcin Mańk
>
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When fascism comes to America, it will be intolerance sold as diversity.
