PostgreSQL Bugs List wrote:
> Problem: in some cases we experience the following problem - we have found
> in the database some _absolutely_ identical rows, despite the fact, that we
> have defined some unique (!) indexes on some of the fields and even primary
> (!) keys, we can see, that the rows are _exactly_ the same. In some cases we
> have seen up to 7 absolutely identical rows, with the same primary keys and
> the same unique indexed fields.
I had the same experiences in 7.3 release and I realized that this is due to
some interaction between vacuum, reindex and update on the same table. See
this posts:
http://archives.postgresql.org/pgsql-bugs/2003-05/msg00060.php
http://www.mail-archive.com/pgsql-admin@postgresql.org/msg09025.html
http://archives.postgresql.org/pgsql-admin/2003-04/msg00407.php
http://archives.postgresql.org/pgsql-bugs/2003-11/msg00129.php
unfortunatelly I never was able to reproduce it.
When you are experiencing this show us the result of this query:
select cmax, cmin, xmax, xmin, * from <table> where <your condition>;
where <your condition> is a filter in order to obtain the rows wit the
primary key duplicated.
However I'm sure that you don't have two row with duplicated primary
key but two version of the same row, the result however is the same.
Are you reindexing your tables regulary ?
Regards
Gaetano Mendola