Re: SELECT my_table.varchar FROM my_table

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От
Tom Lane
Тема
Re: SELECT my_table.varchar FROM my_table
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в 12:44:57
Msg-id
13743.1275320682@sss.pgh.pa.us
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SELECT my_table.varchar FROM my_table Jan Strube <js@deriva.de>
Re: SELECT my_table.varchar FROM my_table Richard Broersma <richard.broersma@gmail.com>
Re: SELECT my_table.varchar FROM my_table Tom Lane <tgl@sss.pgh.pa.us>
Re: SELECT my_table.varchar FROM my_table Jan Strube <js@deriva.de>
Richard Broersma  writes:
> On Mon, May 31, 2010 at 7:48 AM, Jan Strube  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.

			regards, tom lane
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