Re: BUG #15952: UNIQUE CONSTRAINT does not fulfill its' purpose

On Tue, Aug 13, 2019 at 8:23 AM PG Bug reporting form
<noreply(at)postgresql(dot)org> wrote:
> "cimek_irsz_telepules_telepulesresz_kozternev_kozterjelleg_h_key" UNIQUE
> CONSTRAINT, btree (irsz, telepules, telepulesresz, kozternev, kozterjelleg,
> hazszam, hazszambetujel, hazszamvege, lepcsohaz, em, ajto, ajtobetujel)

> I tried to reproduce the issue locally without success. I encountered this
> bug in multiple databases with different table and data. I could upgrade the
> database to version 11 with "pg_upgradecluster 11 main -m upgrade -k", and
> the issue still remain. To make sure it's not a human error, I tried to dump
> the data and restore it. I got duplicate key error as expected.

How old is the duplicate data? I guess you are using the Hungarian
locale as the default collation for your database (see "Collate" in
the output of \l, or check for explicit collations on the relevant
columns). I think that is one of the collations that has moved around
a bit in recent years in glibc. For example:

https://sourceware.org/bugzilla/show_bug.cgi?id=13547

--
Thomas Munro
https://enterprisedb.com