From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | csegyud(at)vnet(dot)hu, "'Reid Thompson'" <Reid(dot)Thompson(at)ateb(dot)com>, "Pgsql-General(at)Postgresql(dot)Org (E-mail)" <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: What does count(*) count? |
Date: | 2003-12-31 17:37:52 |
Message-ID: | 200312311737.hBVHbqG15935@candle.pha.pa.us |
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Lists: | pgsql-general |
Tom Lane wrote:
> =?iso-8859-1?Q?Egy=FCd_Csaba?= <csegyud(at)vnet(dot)hu> writes:
> > I've got it, but I don't know the reason of it.
> > In the database table the records have duplicated and I've two rows for
> > every primary key - with different OIDs.
>
> Sure sounds like a child table to me.
>
> > Is there any safe method to get rid of only one of each duplicated row?
>
> Drop the child table.
This does illustrate an unusual case where a unique index does not
guarantee unique rows from a table:
test=> CREATE TABLE t1 (x INT);
CREATE TABLE
test=> CREATE UNIQUE INDEX ii ON t1(x);
CREATE INDEX
test=> CREATE TABLE t2 (y INT) inherits (t1);
CREATE TABLE
test=> INSERT INTO t1 VALUES (1);
INSERT 17389 1
test=> INSERT INTO t2 VALUES (1,2);
INSERT 17390 1
test=> SELECT * FROM t1;
x
---
1
1
(2 rows)
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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