Re: 7.4: CHAR padding inconsistency

From: Troels Arvin <troels(at)arvin(dot)dk>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: 7.4: CHAR padding inconsistency
Date: 2003-11-20 19:16:44
Message-ID: pan.2003.11.20.19.16.42.163605@arvin.dk
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(I already responded to Bruce, but the response seems to be stuck in some
mailing list, waiting for approval. Trying again:)

On Wed, 19 Nov 2003 14:50:24 -0500, on the BUGS-liste, Bruce Momjian wrote:

> Anyway, what did you want it to output? "AAA hey"? We could do
> that, but I assume most people wouldn't expect that output?

I certainly depends on their background. Personally, the padding
characteristics of the CHAR type was one of the first things about SQL
that I learned (the hard way). Oracle and DB2 people should be used to
PostgreSQL's old behaviour.

The CHAR type may seem strange to some, but they may then just
use VARCHAR.

> How do other databases handle this?

I've started writing about it here:
http://troels.arvin.dk/db/rdbms/#data_types-char

Some of my test-material is also online:
http://troels.arvin.dk/db/tests/chartest-20031119a/

My summary:

With regard to CHAR-handling, PostgreSQL 7.4 is now in opposition to
- previous versions of PostgreSQL; bad enough on its own,
because there doesn't seem to have been a good discussion
about it first - I can only find a few messages about it [1]
- DB2
- Oracle
- MSSQL (which also behaves in a non-standard way,
but different from PostgreSQL 7.4)
7.4 is close to how MySQL works, though.

I'm sorry about not testing this before 7.4 went gold, but I believe that
this is a bug which should be corrected before too much confusion
is created.

Reference 1:
An interesting one is this one:
http://article.gmane.org/gmane.comp.db.postgresql.devel.general/10958/match=char+padding

--
Greetings from Troels Arvin, Copenhagen, Denmark

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