Re: [HACKERS] Re: type coersion (was OR clause status)

> If we come near release time, and no one has been able to penetrate the
> index handling (to fix cases as simple as "where x = 1 + 1" which have
> never worked) the we could fairly easily go back into the parser and
> brute-force some non-general workarounds to get the few "worse than
> before" cases hacked around.
>
> If we _can_ get the index handling to work more generally, then we have
> substantially enhanced the overall capabilities of Postgres.
>
> So far, I haven't seen cases where the parser has tried to do "the wrong
> thing", only cases where "the right thing" causes the index handling to
> miss the boat...

OK, here is what I have.  I have a table called test, with one
attribute.  I execute:

    select * from test where oid = 3;

and the output plan is:

    (
       { EXPR
       :typeOid 0
       :opType op
       :oper
          { OPER
          :opno 1137
          :opid 0
          :opresulttype 16
          }

       :args (
          { VAR
          :varno 1
          :varattno -2
          :vartype 26
          :vartypmod -1
          :varlevelsup 0
          :varnoold 1
          :varoattno -2
          }

          { CONST
          :consttype 23
          :constlen 4
          :constisnull false
          :constvalue  4 [  3  0  0  0 ]
          :constbyval true
          }
       )
       }
    )

Why does the Var have a type 26(int), and the constant a type of
23(oid)?  Where's the conversion function?

Now, the existance of the function doesn't help either, but that is a
different problem:

    test=> explain select * from test where oid = oid(3);
    NOTICE:  QUERY PLAN:

    Seq Scan on test  (cost=1936.05 size=4916 width=8)

Is it because there is a int4eqoid() function?  How to use an index on that?

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