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Re: constraints and sql92 information_schema compliance

From: "Clark C(dot) Evans" <cce(at)clarkevans(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: josh(at)agliodbs(dot)com, pgsql-hackers(at)postgresql(dot)org, Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>, "Clark C(dot) Evans" <cce(at)clarkevans(dot)com>, Bruno Wolff III <bruno(at)wolff(dot)to>
Subject: Re: constraints and sql92 information_schema compliance
Date: 2006-02-27 18:37:03
Message-ID: 20060227183703.GA99481@prometheusresearch.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Mon, Feb 27, 2006 at 11:39:30AM -0500, Tom Lane wrote:
| Josh Berkus <josh(at)agliodbs(dot)com> writes:
| >> No way.  The entire point of information_schema is that it is standard;
| >> adding non-spec things to it renders it no better than direct access
| >> to the PG catalogs.
| >
| > Hmmm ... so, per you, we can't add extra views covering non-spec
| > objects to the information_schema (like aggregates) because we
| > can't modify it in any way.  But per Peter we can't add new
| > views to the pg_catalog because we want people to use
| > information_schema.   I sense a catch-22 here. 

| I doubt Peter really meant that we can't add any new views; in
| particular, for information that is not available from the standard
| information_schema it's certainly silly to claim that people should go
| to information_schema for it.  I do see his point that we shouldn't
| unnecessarily duplicate functionality that's available in a standardized
| view.

If my opinion is worth anything here, nothing should go in the
information_schema unless is is specified in one of the SQL1992,
SQL1999, or SQL2003 specifications.  According to my objectives,
if it isn't in the information_schema, I should not be using it.
I've been using information_schema reflectively, and would have
been confused to see anything in there that wasn't in the specs.

| I do have doubts about adding any large number of add-on views to
| pg_catalog, because of the privileged place of that schema in search
| paths.  It'd be better to put them in a separate schema ("pg_info"
| maybe?) where they'd pose less risk of conflicts with user-defined names.
| Does newsysviews already do this?

A separate pg_info probably would not hurt, I suppose.

Best,

Clark

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