Hi hackers,
I have an SQL-question and a related core dump :-)
> create table test
> (
> col1 text,
> col2 text,
> col3 text
> );
> CREATE
> insert into test values ('one', 'two', 'three');
> INSERT 96299 1
> select col1, count(*) from test group by col1;
> col1|count
> ----+-----
> one | 1
> (1 row)
Now I am going to do something illegal:
> select col1, col3, count(*) from test group by col1;
> ERROR: parser: illegal use of aggregates or non-group column in target list
Obviously, I did not use the aggregate correctly, but look at the last
bit of this error message. If I understand this correctly, all the columns
in the target list must also be stated in the grouping list. In a way,
this makes sense, because the extra columns in the target list
would be undefined: these columns would originate from a random row (tuple)
per group.
My question: is the following query legal?
> select col1, col3 from test group by col1;
> col1|col3
> ----+-----
> one |three
> (1 row)
Shouldn't Postgres complain about 'col3'? It is not in the grouping list.
What actually brought me to that question is a core dump in a (faulty)
query which, after isolating the problem, looks like this:
> select col1, col3 from test where 1 = 1 group by col1;
> FATAL: unrecognized data from the backend. It probably dumped core.
> FATAL: unrecognized data from the backend. It probably dumped core.
If I delete the '1 = 1' or replace 'col3' by 'col2' the query produces
normal results. I'm running the snapshot of April 6 on Linux kernel 2.0.33.
Cheers,
Ronald
