Обсуждение: 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.
Cya...
- K
Kristofer Munn * http://www.munn.com/~kmunn/ * ICQ# 352499 * AIM: KrMunn
> 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. -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania19026
>
> > 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.
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#======================================== jwieck@debis.com (Jan Wieck) #
> > > > > 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. -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania19026
> 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. This now fixed. -- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610) 853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania19026