Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!news.swapon.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Harry Tuttle Newsgroups: comp.databases Subject: Re: Q: is INDEX synonymous with KEY in SQL92? Date: Thu, 03 Oct 2013 15:51:45 +0200 Lines: 24 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: individual.net +nHTNnjOe27tzZJCXz3ejAhJ/iZelF/VLNP7Xdz9hNDVm7G2E= Cancel-Lock: sha1:2xCoSxdScccX00WLZjNq+3oikqs= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.1.21) Gecko/20090302 Thunderbird/2.0.0.21 Mnenhy/0.7.5.666 In-Reply-To: Xref: csiph.com comp.databases:441 Norbert_Paul wrote on 03.10.2013 13:48: > No. I am just referring to what I learned at university on database > implementation. See for example p. 60 in > http://wwwiti.cs.uni-magdeburg.de/iti_db/lehre/db2_en/db2-md-english.pdf I assume you are referring to slide 2-30 and 2-31 Those statements seem to be strongly influenced by the way SQL Server (or MySQL) implement a primary key. > Note that the majority (MySQL, SQL Server) of your examples > (MySQL, SQL Server, "not all DBMS") also works that way. Hence your exaples > support "usually" whereas "all" would have been wrong. My "example" was not an "example" it was what I assumed you had in mind. e.g. Oracle, Postgres, DB2, Firebird, Informix, Vertica, Ingres and Cubrid do not distinguish between a "primary index" and a "secondary" index i.e. they don't automatically create a clustered index on the primary key - not all of them actually have such a thing as a clustered index. Teradata does have the notion of a "primary index" but AFAIK that is not a clustered index, it's just the one created to back the primary key definition. Oracle and DB2 do have a concept of a "clustered index", but they don't automatically create one when you define a primary key constraint