From: "Edward W. Rouse" <erouse@comsquared.com>
To: <pgsql-sql@postgresql.org>
References: <00b701cb38c0$d64fc760$82ef5620$@com> <20100810194433.GA2021@tux>
In-Reply-To: <20100810194433.GA2021@tux>
Subject: Re: Duplicate rows
Date: Tue, 10 Aug 2010 16:42:48 -0400
Message-ID: <00c801cb38cc$9814b990$c83e2cb0$@com>
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I am trying to test this but get an error.

select ctid, * from test where id < 3000000 order by id, ctid;
ERROR:  could not identify an ordering operator for type tid
HINT:  Use an explicit ordering operator or modify the query.

If I do a select I get this:

select ctid, * from test where id < 3000000 order by id;     =20
  ctid   |   id    | activated | wake_up_time=20

(108,22) |     316 | f         |             =20
 (36,17) |     316 | f         |             =20
(used 2 rows only for brevity

And when I tried max(ctid) I got:

ERROR:  function max(tid) does not exist
HINT:  No function matches the given name and argument types. You may =
need
to add explicit type casts.

I appreciate all the help and this feels like I'm almost there.
Thanks


Edward W. Rouse

-----Original Message-----
From: pgsql-sql-owner@postgresql.org =
[mailto:pgsql-sql-owner@postgresql.org]
On Behalf Of Andreas Kretschmer
Sent: Tuesday, August 10, 2010 3:45 PM
To: pgsql-sql@postgresql.org
Subject: Re: [SQL] Duplicate rows

Edward W. Rouse <erouse@comsquared.com> wrote:

> Is there any way to remove a duplicate row from a table? Not my db but =
I
have
> to work with it. On version 7.4 right now.
>=20

How to select the right records?

You can try to use the ctid-column, see my simple example:

test=3D# select * from dups ;
 i
---
 1
 1
 1
 2
 2
 3
 4
(7 Zeilen)

Zeit: 0,145 ms
test=3D*# delete from dups where (ctid, i) not in (select max(ctid), i =
from
dups group by i);
DELETE 3
Zeit: 0,378 ms
test=3D*# select * from dups ;
 i
---
 1
 2
 3
 4
(4 Zeilen)


Andreas
--=20
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."   (unknown)
Kaufbach, Saxony, Germany, Europe.              N 51.05082=B0, E =
13.56889=B0

--=20
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