Re: Index oddity

Thanks Rod,

This setting has no effect however.  If I set statistics to 1000, or
even 0, (and then reanalyze the table) I see no change in the behaviour
of the query plans.  i.e. there is still the odd transtion in the plans
at diagonalSize = 50.

Ken



On Wed, 2004-06-09 at 13:12, Rod Taylor wrote:
> It seems to believe that the number of rows returned for the >49.999
> case will be 4 times the number for the >50 case. If that was true, then
> the sequential scan would be correct.
> 
> ALTER TABLE  ALTER COLUMN diagonalsize SET STATISTICS 1000;
> ANALZYE ;
> 
> Send back EXPLAIN ANALYZE output for the >49.999 case.
> 
> > The query plan for diagonalSize > 50.000 is ...
> > 
> > Index Scan using nrgfeature_xys_index on nrgfeature f 
> > (cost=0.00..17395.79 rows=4618 width=220)
> >    Index Cond: ((upperrightx > 321264.236977215::double precision) AND
> > (lowerleftx < 324046.799812083::double precision) AND (upperrighty >
> > 123286.261898636::double precision) AND (lowerlefty <
> > 124985.927450476::double precision) AND (diagonalsize > 50::double
> > precision))
> > 
> > ... while for diagonalSize > 49.999 is ...
> > 
> >  Seq Scan on nrgfeature f  (cost=0.00..31954.70 rows=18732 width=220)
> >    Filter: ((upperrightx > 321264.236977215::double precision) AND
> > (lowerleftx < 324046.799812083::double precision) AND (upperrighty >
> > 123286.261898636::double precision) AND (lowerlefty <
> > 124985.927450476::double precision) AND (diagonalsize > 49.999::double
> > precision))
> 
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
>       joining column's datatypes do not match
>