Re: [HACKERS] Misleading Error Message

> >
> > > Hi all.  Was working tonight and ran into the following error.  Doing a
> > > union between two selects (to get around the lack of outer joins - hint
> > > hint), I was getting the error:
> > >
> > >         ERROR: Each UNION clause must have the same number of columns
> > >
> > > Upon examining the SQL statement in question, I verified that it did,
> > > indeed, have the same number of columns.  After some fiddling, I found the
> > > actual problem was that I was doing an ORDER BY on a column which was not
> > > being included in the two select statements.  Unfortunately, the error
> > > message wasn't pointing at that.
> > >
> > > I'm not sure if this is just a simple change or implies other problems
> > > with the parser but I thought I'd toss it out onto the pile.
> >
> > Tom Lane discovered it a few days ago in relation to INSERT INTO table
> > SELECT * FROM TABLE ORDER BY col1, and col1 was not in the select target
> > list.  It shows an error.  We are looking at solutions.
> 
>     This  might  also  interfere with latest changes I did in the
>     rewrite system. Parser and rewriter now add  junk  attributes
>     to  the  targetlist.   I  think the problem is that the union
>     code (where the check is done)  doesn't  recognize  that  the
>     unequal  length of the targetlists is due to junk attributes.

I have added code to the parser and rewrite checks to skip counting of
resjunk nodes in checking for UNION length equality.  This should fix
the problem.

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