BUG #1127: ALTER SEQUENCE bug
The following bug has been logged online:
Bug reference: 1127
Logged by: Piotr Konieczny
Email address: znahor@vix.netsync.pl
PostgreSQL version: 7.4
Operating system: Linux
Description: ALTER SEQUENCE bug
Details:
ALTER SEQUENCE doesn't work properly, when only first value has been readed
from sequence:
test=# create TABLE t (s serial, t text);
NOTICE: CREATE TABLE will create implicit sequence "t_s_seq" for "serial"
column "t.s"
NOTICE: CREATE TABLE will create implicit sequence "t_s_seq" for "serial"
column "t.s"
CREATE TABLE
test=# insert into t (t) VALUES ('1');
INSERT 17151 1
test=# select * from t;
s | t
---+---
1 | 1
(1 row)
test=# delete from t;
DELETE 1
test=# ALTER sequence t_s_seq restart 1;
ALTER SEQUENCE
test=# insert into t (t) VALUES ('1');
INSERT 17152 1
test=# select * from t;
s | t
---+---
2 | 1
(1 row)
test=# delete from t;
DELETE 1
test=# ALTER sequence t_s_seq restart 1;
ALTER SEQUENCE
test=# insert into t (t) VALUES ('1');
INSERT 17153 1
test=# select * from t;
s | t
---+---
1 | 1
(1 row)
test=#
"PostgreSQL Bugs List" <pgsql-bugs@postgresql.org> writes:
ALTER SEQUENCE doesn't work properly, when only first value has been readed
from sequence:
Yup, you're right; this was sloppily coded. I've applied the attached
patch.
regards, tom lane
Index: sequence.c
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/commands/sequence.c,v
retrieving revision 1.103.2.1
diff -c -r1.103.2.1 sequence.c
*** sequence.c 24 Nov 2003 16:54:15 -0000 1.103.2.1
--- sequence.c 6 Apr 2004 16:28:03 -0000
***************
*** 315,346 ****
seq = read_info(elm, seqrel, &buf);
page = BufferGetPage(buf);! /* copy old values of options */
! new.increment_by = seq->increment_by;
! new.max_value = seq->max_value;
! new.min_value = seq->min_value;
! new.cache_value = seq->cache_value;
! new.is_cycled = seq->is_cycled;
! new.last_value = seq->last_value;
/* Check and set new values */
init_params(stmt->options, &new, false);
/* Now okay to update the on-disk tuple */
! seq->increment_by = new.increment_by;
! seq->max_value = new.max_value;
! seq->min_value = new.min_value;
! seq->cache_value = new.cache_value;
! seq->is_cycled = new.is_cycled;
! if (seq->last_value != new.last_value)
! {
! seq->last_value = new.last_value;
! seq->is_called = false;
! seq->log_cnt = 1;
! }
! /* save info in local cache */
! elm->last = new.last_value; /* last returned number */
elm->cached = new.last_value; /* last cached number (forget
* cached values) */
--- 315,331 ----
seq = read_info(elm, seqrel, &buf);
page = BufferGetPage(buf);! /* Copy old values of options into workspace */
! memcpy(&new, seq, sizeof(FormData_pg_sequence));
/* Check and set new values */
init_params(stmt->options, &new, false);
/* Now okay to update the on-disk tuple */
! memcpy(seq, &new, sizeof(FormData_pg_sequence));
! /* Clear local cache so that we don't think we have cached numbers */
! elm->last = new.last_value; /* last returned number */
elm->cached = new.last_value; /* last cached number (forget
* cached values) */
***************
*** 1008,1020 ****
--- 993,1011 ---- /* START WITH */
if (last_value != (DefElem *) NULL)
+ {
new->last_value = defGetInt64(last_value);
+ new->is_called = false;
+ new->log_cnt = 1;
+ }
else if (isInit)
{
if (new->increment_by > 0)
new->last_value = new->min_value; /* ascending seq */
else
new->last_value = new->max_value; /* descending seq */
+ new->is_called = false;
+ new->log_cnt = 1;
}
/* crosscheck */