Tablespaces oddity?

From: Philip Yarra <philip(at)utiba(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Tablespaces oddity?
Date: 2006-03-28 06:12:26
Message-ID: 200603281612.26679.philip@utiba.com
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Hi folks after discussing this on IRC today (thanks G_SabinoMullane!), I'm
still surprised by this behaviour on 8.1.3:

pyarra=# create TABLESPACE spctables location '/mnt/pg_tables/data';
CREATE TABLESPACE
pyarra=# create table foo(id int) tablespace spctables;
CREATE TABLE
pyarra=# \d foo
Table "public.foo"
Column | Type | Modifiers
--------+---------+-----------
id | integer |
Tablespace: "spctables"

So far, so good...

pyarra=# CREATE DATABASE spctest TABLESPACE spctables;
CREATE DATABASE
pyarra=# \c spctest;
You are now connected to database "spctest".
spctest=# create table foo(id int) tablespace spctables;
CREATE TABLE
spctest=# create table bar(id int);
CREATE TABLE
spctest=# \d foo
Table "public.foo"
Column | Type | Modifiers
--------+---------+-----------
id | integer |

spctest=# \d bar
Table "public.bar"
Column | Type | Modifiers
--------+---------+-----------
id | integer |

I hoped that these last two tables would also be listed as being on spctables.

I think the issue is that pg_class.reltablespace = 0 where these objects are
created on the default tablespace for this database. I can find out which
tablespace the objects are really on with:

select relname, COALESCE(t.spcname,(select spcname from pg_tablespace where
oid = (select dattablespace from pg_database where datname
=current_database()))) as tablespace from pg_class c left join pg_tablespace
t on (t.oid = c.reltablespace)

Someone else might be able to see a better way to write this query, but I
think it would be good if \d could show this information, when you really
want to know which tablespace an object is on.

Note also that \l won't show you the tablespace for a DB, so you need to query
pg_database to even know which is the default tablespace for a DB. It's not
impossible, just harder than it needs to be, I reckon.

Any thoughts?

Regards, Philip.

--

"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan

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