Re: SELECT my_table.varchar FROM my_table

Am 31.05.2010 17:44, schrieb Tom Lane:
> Richard Broersma<richard.broersma@gmail.com>  writes:
>
>> On Mon, May 31, 2010 at 7:48 AM, Jan Strube<js@deriva.de>  wrote:
>>
>>> I accidentally encountered a feature in Postgres 8.3 that I couldn't find in
>>> the documentation while submitting a query like
>>>
>>> SELECT my_table.varchar FROM my_table
>>>
>>> which returns a concatenated string of all field values per row.
>>> I wonder where this is documented (and if it has something to do with
>>> composite types).
>>>
>>> Can anyone please explain?
>>>
>
>> I don't really know, but the result looks more like a single field
>>
> It's equivalent to (my_table.*)::varchar.  We've seen enough people
> confused by this (or the equivalent cases with text and name as
> the target type) that I wonder if we should intentionally break the
> symmetry and disable treating this case as a cast.  Although I do
> rather wonder what the OP expected to happen here.
>

I didn't expect anything special, because my original statement was
actually a typo. So I was just amazed that I didn't get an error.

Thanks for the explanation,
Jan