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

Unprivileged user wrote:
> 
>   PostgreSQL version : 6.4.2
>
...
> 
> Here is an example session. Note that in first SELECT
> backend uses index scan, and in second one it uses
> sequental scan.
> 
> == cut ==
> bamby=> create table table1 (field1 int);
> CREATE
> bamby=> create index i_table1__field1 on table1 (field1);
> CREATE
> bamby=> explain select * from table1 where field1 = 1;
> NOTICE:  QUERY PLAN:
> 
> Index Scan using i_table1__field1 on table1  (cost=0.00 size=0 width=4)
         ^^^^^^
 
Hmmm... Seems that vacuum wasn't run for table1.
Why is index used ?!!!
It's bug!

> EXPLAIN
> bamby=> explain select * from table1 where field1 = -1;
> NOTICE:  QUERY PLAN:
> 
> Seq Scan on table1  (cost=0.00 size=0 width=4)

Run 

vacuum table1

Vadim