Sorry, the patch had obvious bug..
-+
Int32GetDatum(inputTypeMod),
++
Int32GetDatum(targetTypeMod),
regards,
> Hello, I think this is a bug.
>
> The core of this problem is that coerce_type() fails for Var of
> type UNKNOWNOID.
>
> The comment for the function says that,
>
> > * The caller should already have determined that the coercion is possible;
> > * see can_coerce_type.
>
> But can_coerce_type() should say it's possible to convert from
> unknown to any type as it doesn't see the target node type. I
> think this as an inconsistency between can_coerce_type and
> coerce_type. So making this consistent would be right way.
>
> Concerning only this issue, putting on-the-fly conversion for
> unkown nonconstant as attached patch worked for me. I'm not so
> confident on this, though..
>
> regards,
>
> At Wed, 22 Apr 2015 23:26:43 -0700, Jeff Davis <pg...@j-davis.com> wrote in
> <1429770403.4604.22.camel@jeff-desktop>
> > On Wed, 2015-04-22 at 20:35 -0700, David G. Johnston wrote:
> >
> > > But the fact that column "b" has the data type "unknown" is only a
> > > warning - not an error.
> > >
> > I get an error:
> >
> > postgres=# SELECT ' '::text = 'a';
> > ?column?
> > ----------
> > f
> > (1 row)
> >
> > postgres=# SELECT a=b FROM (SELECT ''::text, ' ') x(a,b);
> > ERROR: failed to find conversion function from unknown to text
--
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
index a4e494b..2e3a43c 100644
--- a/src/backend/parser/parse_coerce.c
+++ b/src/backend/parser/parse_coerce.c
@@ -221,7 +221,7 @@ coerce_type(ParseState *pstate, Node *node,
return node;
}
}
- if (inputTypeId == UNKNOWNOID && IsA(node, Const))
+ if (inputTypeId == UNKNOWNOID)
{
/*
* Input is a string constant with previously undetermined type. Apply
@@ -275,6 +275,29 @@ coerce_type(ParseState *pstate, Node *node,
targetType = typeidType(baseTypeId);
+ /* Perform on the fly conversion for non-constants */
+ if(!IsA(node, Const))
+ {
+ Form_pg_type typform = (Form_pg_type) GETSTRUCT(targetType);
+ Node *result =
+ (Node*) makeFuncExpr(typform->typinput,
+ targetTypeId,
+ list_make3(node,
+ makeConst(OIDOID, -1, InvalidOid,
+ sizeof(Oid),
+ ObjectIdGetDatum(InvalidOid),
+ false, true),
+ makeConst(INT4OID, -1, InvalidOid,
+ sizeof(uint32),
+ Int32GetDatum(targetTypeMod),
+ false, true)),
+ InvalidOid, InvalidOid,
+ COERCE_IMPLICIT_CAST);
+ ReleaseSysCache(targetType);
+
+ return result;
+ }
+
newcon->consttype = baseTypeId;
newcon->consttypmod = inputTypeMod;
newcon->constcollid = typeTypeCollation(targetType);
--
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