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

> Bruce Momjian wrote:
> >
> > My guess is that the creation of the index updates the table size
> > statistics.
>
> Yes.
>
> > However, when I see zero size, I don't know if it is accurate, or if
> > someone has added rows since the last vacuum/index creation, so I think
> > it is correct to use an index on a zero-length table if it is
> > appropriate. If the size is 1, I will assume that number is accurate,
> > and do a sequential scan.
> >
> > Does that make sense?
>
> Yes. But we have to fix SeqScan for field1 = -1...

The basic problem is that the -1 is stored as:

{ EXPR
:typeOid 0
:opType op
:oper
{ OPER
:opno 558
:opid 0
:opresulttype 23
}

:args (
{ CONST
:consttype 23
:constlen 4
:constisnull false
:constvalue 4 [ 4 0 0 0 ]
:constbyval true
}
)

This is clearly undesirable, and causes the optimizer to think it can't
use the index.

Is this bug report for 6.4.*, or did are you running the current
development tree? I assume you are running 6.4.*, and am surprised this
did not show as a larger problem.

I will look in the grammer for a fix. This should come across as a
single -4 constant.

--
Bruce Momjian | http://www.op.net/~candle
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