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+From reedstrm@rice.edu Wed May 23 10:59:42 2001
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+Date: Wed, 23 May 2001 09:56:41 -0500
+From: "Ross J. Reedstrom" <reedstrm@rice.edu>
+To: Bruce Momjian <pgman@candle.pha.pa.us>
+Subject: Re: [HACKERS] Re: [GENERAL] Re: [GENERAL] Queries across multiple databases ?(was: SELECT from a table in another database).
+Message-ID: <20010523095641.D23741@rice.edu>
+References: <004c01c0e214$ce6c4800$1001a8c0@archonet.com> <200105221131.f4MBVIc28574@candle.pha.pa.us>
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+In-Reply-To: <200105221131.f4MBVIc28574@candle.pha.pa.us>; from pgman@candle.pha.pa.us on Tue, May 22, 2001 at 07:31:18AM -0400
+Status: ORr
+
+Bruce -
+Around the first of the year, I started playing around with a schema
+implementation. As you may recall, my first crack at changing file storage
+names about a year ago was motivated by the need to avoid collisions
+once schema were available.
+
+Anyway, now that Vadim has removed a lot of the internal dependence
+on relname for keeping track of relations, using the new relfinenode
+many places relname used to be used, it seems to me that adding a
+parallel schemaname to all the data structures that use relname isn't
+as cumbersome as Peter might think. I hadn't tackled the relcache yet:
+perhaps concatenating the schemaname and relname to use as the hash key
+is the way to go for that.
+
+Unfortunately, all that code is now 4 months old, and on my machine
+at home. I has started with the rangetable entries, because hacked the
+parser to allow 'SELECT * FROM schemaname.tablename' was easier than
+'select schemaname.tablename.fieldname FROM', since the dot function
+calling convention isn't allowed in the range list, while it is in the
+target list.
+
+I seem to recall tripping up on the query plan printer, of all things,
+before other, paying work pushed it aside. I'll see if I can update that
+code to the current tree, and send you something, if you'd like.
+
+Ross
+
+
+
+On Tue, May 22, 2001 at 07:31:18AM -0400, Bruce Momjian wrote:
+> > > I'm not sure whether it is quite the way to do it, but I'd have a better
+> > > time with things if I could span databases in a single request. Are
+> > > there theoretical problems with spanning databases in a single query? Is
+> > > it a feature of bad database design & implementation?
+> >
+> > I think the developers are planning full schema support for the relatively
+> > near future (possibly even 7.2, but check the archives and see what's been
+> > said). Although it looks easy to access a table from another database,
+> > things can rapidly become more complicated as you start having to deal with
+> > transactions, triggers, rules, constraints...
+>
+> Schema is on my radar screen for 7.2. I am waiting to do some research
+> in what needs to be done, but my initial idea is to use the system cache
+> to do namespace mapping, just like is done now for temp tables.
+>
+> --
+> Bruce Momjian | http://candle.pha.pa.us
+> pgman@candle.pha.pa.us | (610) 853-3000
+> + If your life is a hard drive, | 830 Blythe Avenue
+> + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
+>
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