From: Tom Lane <tgl@sss.pgh.pa.us>
To: Stephan Szabo <sszabo@megazone23.bigpanda.com>
Cc: Peter Eisentraut <peter_e@gmx.net>
Cc: pgsql-hackers@postgreSQL.org, Fernando Nasser <fnasser@redhat.com>
Subject: Re: RFD: schemas and different kinds of Postgres objects
Date: Wed, 23 Jan 2002 11:46:58 -0500
Message-ID: <3159.1011804418@sss.pgh.pa.us> (raw)
In-Reply-To: <20020123083152.W18169-100000@megazone23.bigpanda.com>
References: <20020123083152.W18169-100000@megazone23.bigpanda.com>
Stephan Szabo <sszabo@megazone23.bigpanda.com> writes:
> Wouldn't it make sense to prefer operators/functions earlier in the search
> path for resolving ambiguity. So if you had plus(int4, int4) in my
> schema and plus(int8, int8) in system, and they'd otherwise cause an
> ambiguity failure for the query, use the plus(int4, int4) on mine. It
> seems not too far from having the search path shadow later exact matches.
Given the complexity of the resolution rules (cf.
http://developer.postgresql.org/docs/postgres/typeconv.html),
it's not clear that we can determine exactly which "later" entry ought
to be blamed for causing a resolution failure. I'd be interested to
hear Lockhart's opinion on this --- but my gut feeling is we don't
want to go there. The resolution rules are already complicated enough,
and I think layering an additional mechanism like that onto them might
make the behavior totally unpredictable.
Another problem is that this would probably cause earlier namespace
entries to be over-preferred. For example, suppose that the system
namespace has plus(int4,int4) and plus(int8,int8) and you choose to
define plus(int4,int8) locally. I believe you'd suddenly find yours
being used for *any* cross-datatype addition, including cases that
had nothing obvious to do with either int4 or int8 ...
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, sszabo@megazone23.bigpanda.com, peter_e@gmx.net, fnasser@redhat.com
Subject: Re: RFD: schemas and different kinds of Postgres objects
In-Reply-To: <3159.1011804418@sss.pgh.pa.us>
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