Re: [BUGS] Running queries on inherited tables

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Michael Richards <miker(at)scifair(dot)acadiau(dot)ca>
Cc: pgsql-sql(at)postgresql(dot)org, pgsql-bugs(at)postgresql(dot)org
Subject: Re: [BUGS] Running queries on inherited tables
Date: 1999-09-12 17:07:37
Message-ID: 2894.937156057@sss.pgh.pa.us
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Michael Richards <miker(at)scifair(dot)acadiau(dot)ca> writes:
> I was fooling with inheritance today. From the page at:
> http://www.postgresql.org/docs/user/inherit.htm
> Here the * after cities indicates that the query should be run over cities
> and all classes below cities in the inheritance hierarchy. Many of the
> commands that we have
> already discussed -- SELECT, UPDATE and DELETE -- support this * notation,
> as do others, like ALTER TABLE.

The doc is wrong here --- UPDATE and DELETE don't support *. They should.

> More playing followed... If I alter table on cities and add a column, is
> it not expected that the additional col should appear in the tables which
> inherit from cities?

You have to say "alter table cities*", I believe, otherwise only cities
is changed. Which is pretty broken --- if inheritance means anything,
then it ought to mean that the alteration is *inherently* applied to all
the child tables too, and you shouldn't have the option. In general,
however, beware that alteration of inheritance structures is pretty
thoroughly broken --- see various complaints in the pghackers archives
(mostly from Chris Bitmead, I think). ALTER TABLE really needs a
reimplementation from the ground up, but I dunno when anyone will get
around to it.

regards, tom lane

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