Re: [HACKERS] Bug - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] Bug
Date
Msg-id 29257.937577900@sss.pgh.pa.us
Whole thread Raw
In response to Bug  (Oleg Broytmann <phd@sun.med.ru>)
Responses Re: [HACKERS] Bug
Re: Bug
List pgsql-hackers
Oleg Broytmann <phd@sun.med.ru> writes:
> ran=> create table test1 (n int default nextval('seq_test'), t text);
> ran=> insert into test1 ("t") select distinct src from test_source;
> [ doesn't work right ]

My, that's an interesting case.  I think that fits right in with my
remark yesterday that the SELECT inside an INSERT ... SELECT needs
to have a targetlist that's separate from the INSERT's list.  As it
stands, we form a targetlist representing the set of values that need
to be inserted into the target table --- and then the DISTINCT pass
runs on those tuples :-(, because there is nothing else for it to
run on.

In short, this is not a trivial thing to fix.  We need multilevel
query trees...
        regards, tom lane


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