Hi Slony People,

We have a 30 gigabyte database handling about 100M queries a day.  We  
recently started load balancing with slony and pgpool and it's working  
pretty well.  (I've documented a lot of stuff in our wiki -- will  
definitely turn it into a post.)

Anyway we have been getting a few "permission denied for sequence  
sl_action_seq" and had come across http://www.mail-archive.com/slony1-general@gborg.postgresql.org/msg03302.html 
  where it was asserted that "Calling lastval() instead of currval()  
is not safe against concurrent clients to begin with" and :However,  
unless you've stumbled across a bug in Postgres itself, there is  
nothing there that would cause any of the code to access a sequence  
different from the one your application specifies in the call."

I'm pretty sure neither statement is quite true. We determined that  
using currval and lastval *without explicitly stating the sequence*  
will substitute a sequence from the slony schema behind your back.

I've pasted an example here. In the first case, we select lastval and  
we a sequence from slony instead of what we want. (This is on the  
master.) In the second case where we explicitly name the sequence, it  
works.

I don't know that this is a bug or what it would take to fix it, but  
it should probably be documented that you can't use lastval() without  
an explicit sequence ID when doing slony, or something, anyway.

Thanks for great software.

Karl

sdidata=# BEGIN;
BEGIN
asdidata=# INSERT INTO ad_campaign(user_id,type,target)  
values(1,'airport','KMOO');
INSERT 0 1
asdidata=# SELECT lastval();
lastval
---------
157122
(1 row)
asdidata=# ROLLBACK;
ROLLBACK
asdidata=#
old way.
asdidata=# begin;
BEGIN
asdidata=# INSERT INTO ad_campaign(user_id,type,target)  
values(1,'airport','KMOO');
INSERT 0 1
asdidata=# SELECT currval('ad_campaign_id_seq');
currval
---------
122
(1 row)
asdidata=# ROLLBACK;
ROLLBACK
asdidata=#
new way