Re: key = currval('tab_key_seq') choses SEQSCAN?! - Mailing list pgsql-general

Eric B.Ridge wrote:
> I suppose this is obvious, but it's volatile because *other* backends
> can change it while the current transaction is still in progress?

No. Other backends don't affect currval, but your own might on a
row-by-row basis. Consider:

regression=# create sequence seq;
CREATE SEQUENCE

regression=# select nextval('seq'), currval('seq'), s from
generate_series(1,4) as t(s);
  nextval | currval | s
---------+---------+---
        1 |       1 | 1
        2 |       2 | 2
        3 |       3 | 3
        4 |       4 | 4
(4 rows)


Joe