If you need to get the actual "current value" without incrementing, try:
SELECT last_value FROM <sequence_name>; This will return the last value returned from a nextval command directly from the sequence properties in the system tables. -----Original Message----- From: Dan Langille [mailto:[EMAIL PROTECTED]] Sent: Thursday, June 06, 2002 12:34 PM To: Nicolas Nolst Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: [ADMIN] [GENERAL] performance issue using DBI On 6 Jun 2002 at 17:14, Oliver Elphick wrote: > On Thu, 2002-06-06 at 14:55, Joshua b. Jore wrote:u > > Don't use currval since some other process might alter the > > sequence between the time you call nextval and currval. > > This is wrong. currval() will always return the last serial assigned in > *the*same*session*. It is not affected by other users at all. Folks, here's a short test which might help. Note the BEGIN. $ psql testing testing=# create sequence test; CREATE testing=# select currval('test'); ERROR: test.currval is not yet defined in this session testing=# select setval('test', 1); setval -------- 1 (1 row) testing=# select currval('test'); currval --------- 1 (1 row) testing=# select currval('test'); currval --------- 1 (1 row) testing=# select currval('test'); currval --------- 1 (1 row) testing=# select currval('test'); currval --------- 1 (1 row) testing=# Then, in another window, I did this: $ psql testing # select nextval('test'); nextval --------- 2 (1 row) testing=# select nextval('test'); nextval --------- 3 (1 row) testing=# select nextval('test'); nextval --------- 4 (1 row) testing=# Then back to the other window: testing=# select currval('test'); currval --------- 1 (1 row) testing=# select nextval('test'); nextval --------- 5 (1 row) testing=# cheers FWIW: I always use nextval when looking for a new ID. -- Dan Langille ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
