Very sorry for the trash.. === Now I found a comment at just where I patched,
> * XXX if the typinput function is not immutable, we really ought to > * postpone evaluation of the function call until runtime. But there > * is no way to represent a typinput function call as an expression > * tree, because C-string values are not Datums. (XXX This *is* > * possible as of 7.3, do we want to do it?) - Is it OK to *now* we can do this? + Is it OK to regard that we can do this *now*? 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 -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
