Re: CREATE TABLE LIKE and tablespaces

From: Christian Ullrich <chris(at)chrullrich(dot)net>
To: pgsql-admin(at)postgresql(dot)org
Subject: Re: CREATE TABLE LIKE and tablespaces
Date: 2013-03-02 18:40:42
Message-ID: kgth37$aup$1@ger.gmane.org
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* David F. Skoll wrote:

> I have an application that creates a daily table from a "prototype"
> table, so something like:
>
> CREATE TABLE data_20130226 LIKE data_prototype INCLUDING DEFAULTS INCLUDING CONSTRATINTS INCLUDING INDEXES;
>
> It would be really nice to be able to add:
>
> INCLUDING TABLESPACE

Workaround:

CREATE OR REPLACE FUNCTION table_tablespace(p_relname regclass)
RETURNS name
LANGUAGE sql
AS $$
SELECT t.spcname
FROM pg_class c
JOIN pg_tablespace t
ON (c.oid = p_relname
AND COALESCE(
NULLIF(c.reltablespace, 0),
(SELECT dattablespace
FROM pg_database
WHERE datname = current_database())) = t.oid);
$$;

-- It is surprisingly difficult to get the tablespace of a table.
-- (Note to self: So *that* is what NULLIF() is for!)

CREATE OR REPLACE FUNCTION create_table_like(p_old regclass, p_new name)
RETURNS regclass
LANGUAGE plpgsql
AS $$
BEGIN
EXECUTE 'CREATE TABLE ' || quote_ident(p_new)
|| ' (LIKE ' || quote_ident(p_old::name)
|| ' INCLUDING DEFAULTS '
|| ' INCLUDING CONSTRAINTS '
|| ' INCLUDING INDEXES) '
|| ' TABLESPACE '|| quote_ident(table_tablespace(p_old))
|| ';';
RETURN p_new::regclass;
END;
$$;

test=> SELECT create_table_like('data_prototype', 'data_20130226');
create_table_like
-------------------
data_20130226

--
Christian

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