Received: from www.wgcr.org (www.wgcr.org [206.74.232.194]) by postgresql.org (Postfix) with ESMTP id 6C23F475BC7 for ; Tue, 16 Jul 2002 12:13:28 -0400 (EDT) Received: from localhost.localdomain ([10.1.2.112]) by www.wgcr.org (8.9.3/8.9.3/WGCR) with ESMTP id MAA15092; Tue, 16 Jul 2002 12:13:22 -0400 Content-Type: text/plain; charset="iso-8859-1" From: Lamar Owen To: Thomas Lockhart , Bruce Momjian Subject: Re: [SQL] line datatype Date: Tue, 16 Jul 2002 12:10:23 -0400 User-Agent: KMail/1.4.1 Cc: Tom Lane , Tim Hart , PostgreSQL-development References: <200207161521.g6GFL5417443@candle.pha.pa.us> <3D343BEA.1B51B9CD@fourpalms.org> In-Reply-To: <3D343BEA.1B51B9CD@fourpalms.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-Id: <200207161210.23948.lamar.owen@wgcr.org> X-Archive-Number: 200207/648 X-Sequence-Number: 25022 On Tuesday 16 July 2002 11:29 am, Thomas Lockhart wrote: > > > We do need a solution for exact dump/reload of floating-point data, > > > but I don't see why the lack of it should be reason to disable access > > > to the LINE type. > > I don't understand why dumping the two point values isn't sufficient. > Which two point values? LINE is handled as an equation, not as points, > unlike the LSEG type which has two points. > One possibility is to have the external representation *be* the same as > LSEG, then convert internally. Then we need to decide how to scale those > points; maybe always using a unit vector is the right thing to do... Lines are entered now by specifying two points, anywhere on the line, right? The internal representation is then slope-intercept? Why not allow either the 'two-point' entry, or direct entry as slope-intercept? How do we represent lines now in output? Do we pick two arbitrary points on the line? If so, I can see Thomas' point here, where the original data entry might have specified two relatively distant points -- but then there's a precision error anyway converting to slope-intercept, if indeed that is the internal representation. So why not dump in slope-intercept form, if that is the internal representation? But, you're telling me floats aren't dumpable/restoreable to exactly the same value? (????) This can't be good. -- Lamar Owen WGCR Internet Radio 1 Peter 4:11