Thread

Re: [HACKERS] Re: [BUGS] General Bug Report: Bug in optimizer

Marc G. Fournier <scrappy@hub.org> — 1999-03-19T13:32:16Z

On Thu, 18 Mar 1999, Bruce Momjian wrote:

> > Bruce Momjian wrote:
> > > 
> > > Let me tell you why I don't think this is a bug.  The optimizer will
> > > choose ordered results over unordered results if the costs are the same.
> > > In this case, the cost of the query is zero, so it chose to use the
> > > index because the index produces an ordered result.
> > > 
> > > This works well for un-vacuumed tables, because it thinks everything is
> > > zero cost, and chooses the index.
> > 
> > Agreed, this is ok as long as
> > 
> > vac=> create table table1 (field1 int);
> > CREATE
> > vac=> insert into table1 values (1);
> > INSERT 1583349 1
> > vac=> create index i_table1__field1 on table1 (field1);
> > CREATE
> > vac=> explain select * from table1 where field1 = 1;
> > NOTICE:  QUERY PLAN:
> > 
> > Seq Scan on table1  (cost=1.03 size=1 width=4)
> > 
> > - SeqScan is used for small tables.
> > 
> > So, only bug reported is left.
> > 
> 
> Can you get on IRC now?  Why are you up so late?

That's something we need on our globe...timezones :)  


Marc G. Fournier                   ICQ#7615664               IRC Nick: Scrappy
Systems Administrator @ hub.org 
primary: scrappy@hub.org           secondary: scrappy@{freebsd|postgresql}.org