Re: [PATCHES] SQL conformance related patch

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Peter Eisentraut <peter_e(at)gmx(dot)net>
Cc: Troels Arvin <troels(at)arvin(dot)dk>, pgsql-patches(at)postgresql(dot)org,pgsql-docs(at)postgresql(dot)org
Subject: Re: [PATCHES] SQL conformance related patch
Date: 2004-11-28 21:35:25
Message-ID: 1101677725.2963.63.camel@localhost.localdomain
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On Fri, 2004-11-26 at 22:34, Peter Eisentraut wrote:
> Simon Riggs wrote:
> > The sections Supported Features and Unsupported Features cover both
> > Mandatory (Core) and Optional features in the same section. It would
> > be better to separate these, just as the SQL standard itself does in
> > Annex F - SQL Feature Taxonomy.
> >

Please note that all that has been suggested is splitting a table into
two pieces, so that it matches the SQL:2003 standard's way of presenting
this information, as laid out in Annex F - SQL Feature Taxonomy.

I found that arrangement useful in understanding the standard and wished
to recommend it to the project.

> > This seems especially important for the Unsupported Features section,
> > since the length of the list makes it look like 100% support is a
> > long way off, whereas it is only 14 features away, and many of them
> > minor [see Troels' low hanging fruit list on this thread]
>
> If the "core" set of features were at all useful in practice then I
> would think about this, but it is not, so we'd just end up arranging
> the tables for marketing purposes instead of information purposes. Ten
> years ago this would have been equivalent to making a separate section
> for SQL 92 Entry level and rejoicing upon completion, while realizing
> that a real-life DBMS needs at least Intermediate level.

I agree completely with your assessment of SQL-92 Entry and Intermediate
level. Having recently spent an hour or two looking at the SQL:2003
standard, I don't think the analogy that SQL:2003 Core is similar to
SQL-92 Entry level is a useful one. I understand why people would think
this, because I would definitely have thought exactly the same, before I
looked.

For example, Microsoft SQL Server claims SQL-92 Entry level. If SQL:2003
were similar then they would simply switch the claim to SQL:2003 without
problem. They do not, because they cannot.

Please review what the list of SQL:2003 Core features contains:
SAVEPOINTS, outer joins, triggers, derived tables, quantified
sub-selects, constraints etc.. but not object-relational features, which
are only Optional. IMHO these features are useful in practice.

Yes, there are also many Optional features that are also desirable.

--
Best Regards, Simon Riggs

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