Re: [GENERAL] MySQL to PostgreSQL, was ENUM type

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>
Cc: Gregory Youngblood <pgcluster(at)netio(dot)org>, Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, Chris Travers <chris(at)travelamericas(dot)com>, Merlin Moncure <merlin(dot)moncure(at)rcsonline(dot)com>, PostgreSQL advocacy <pgsql-advocacy(at)postgresql(dot)org>, pgsql-general <pgsql-general(at)postgresql(dot)org>
Subject: Re: [GENERAL] MySQL to PostgreSQL, was ENUM type
Date: 2005-07-29 19:57:48
Message-ID: 18607.1122667068@sss.pgh.pa.us
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"Jim C. Nasby" <decibel(at)decibel(dot)org> writes:
> Is there any serious impediment to adding unsigned types to PostgreSQL?

Quick, what's the datatype of 12345? And why?

My guess is that transparent support for such a thing would require some
tricky and fragile compromises in the numeric hierarchy's promotion
rules. The handling of smallint is already pretty unsatisfactory
because "12345" is considered int not smallint; adding three or four
unsigned types would make that problem many times worse.

> I don't think these would even have to be in core, if that's a
> concern.

Sure, if you don't need it to work reasonably nicely --- although the
promotion rules are now embedded in pg_cast and hence modifiable, the
initial determination of a datatype for a numeric literal is still
hard-wired in the grammar.

regards, tom lane

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