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Re: Best way to create a sequence generator at run time?

From: Leon Starr <leon_starr(at)modelint(dot)com>
To: pgsql-novice(at)postgresql(dot)org
Subject: Re: Best way to create a sequence generator at run time?
Date: 2010-09-22 20:19:57
Message-ID: 3452B1FA-924B-4B90-8D90-1A53BF0607DB@modelint.com (view raw or flat)
Thread:
Lists: pgsql-novice
I'm converging on a good solution, but have just one (hopefully) problem left.
I need to get the nextval for a sequence whose name has been stored, and is thus
not available prior to runtime.  I am trying to use EXECUTE, but can't seem to get
it right.  Suggestions?

Here's the function extract in question:

create or replace function ...
) returns bigint as 
$$
declare
	self subsystem%rowtype; -- has an attribute where the sequence name is stored
begin
	select * from subsystem into strict self where (name = p_subsystem and domain = p_domain);

	-- self.cnum_generator is a text value holding the name of the previously created sequence
	-- I've tested to ensure that it is holding the correct value, so no worries there, it is a valid sequence

	-- Now here is the trouble - none of these statements seem to work or parse correctly:

	return execute 'nextval(' || self.cnum_generator || ')';  -- NOPE

	new_num := nextval(self.cnum_generator);  -- I didn't expect this one to work, but might as well try, NOPE

	return query execute 'nextval( $1 )' using self.cnum_generator;  -- no good either

	return query execute 'nextval(' || self.cnum_generator || ')';  -- NOPE

	-- accck!  Phhht!  Help!


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Next:From: Leon StarrDate: 2010-09-22 21:04:51
Subject: Re: Best way to create a sequence generator at run time?
Previous:From: Tom LaneDate: 2010-09-22 20:09:57
Subject: Re: pg_dump

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