Thread: Re: [ADMIN] how to alter sequence.
On Wed, 2002-12-04 at 12:29, raja kumar thatte wrote: > Hai friends, > I have a sequence called raj_seq with max value 3000. ... > now i wanted to increase the max value of the raj_seq > to 9999999. > How to do this change? > If i drop and recreate the raj_seq, then i have to > recreate the table and all triggers working on that > table.But it is not an acceptable solution. > So with out droping raj_seq , how do I solve this > problem. Unfortunately there doesn't seem to be any easy way to do this. There is no ALTER SEQUENCE command and you can't use UPDATE on a sequence. Hackers: Could this be a TODO item for 7.4? The easiest way to do this at present is probably to dump the database, edit the dump to change the sequence max_value and then recreate the database from the edited dump. I presume you used CREATE SEQUENCE in order to get such a low max_value. If it were created from a SERIAL datatype, you would also have to edit the table definition to use a pre-created sequence. There is no means of specifying a max_value using SERIAL. -- Oliver Elphick <olly@lfix.co.uk> LFIX Limited
Oliver Elphick kirjutas K, 04.12.2002 kell 19:06: > On Wed, 2002-12-04 at 12:29, raja kumar thatte wrote: > > Hai friends, > > I have a sequence called raj_seq with max value 3000. > ... > > now i wanted to increase the max value of the raj_seq > > to 9999999. > > How to do this change? > > If i drop and recreate the raj_seq, then i have to > > recreate the table and all triggers working on that > > table.But it is not an acceptable solution. > > So with out droping raj_seq , how do I solve this > > problem. > > Unfortunately there doesn't seem to be any easy way to do this. There > is no ALTER SEQUENCE command and you can't use UPDATE on a sequence. > > Hackers: Could this be a TODO item for 7.4? This seems to work - as an example why we need the TODO ;) hannu=# update seq set max_value = 99; ERROR: You can't change sequence relation seq hannu=# update pg_class set relkind = 'r' where relname = 'seq'; UPDATE 1 hannu=# update seq set max_value = 99; UPDATE 1 hannu=# update pg_class set relkind = 'S' where relname = 'seq'; UPDATE 1 hannu=# select * from seq; sequence_name | last_value | increment_by | max_value | min_value | cache_value | log_cnt | is_cycled | is_called ---------------+------------+--------------+-----------+-----------+-------------+---------+-----------+----------- seq | 1 | 1 | 99 | 1 | 1 | 1 | f | f (1 row) I can't really recommend it, because it may (or may not ;) have some unwanted behaviours as well; > > The easiest way to do this at present is probably to dump the database, > edit the dump to change the sequence max_value and then recreate the > database from the edited dump. I presume you used CREATE SEQUENCE in > order to get such a low max_value. If it were created from a SERIAL > datatype, you would also have to edit the table definition to use a > pre-created sequence. There is no means of specifying a max_value using > SERIAL. -- Hannu Krosing <hannu@tm.ee>
On 4 Dec 2002 at 20:41, Hannu Krosing wrote: > hannu=# update seq set max_value = 99; > ERROR: You can't change sequence relation seq > hannu=# update pg_class set relkind = 'r' where relname = 'seq'; > UPDATE 1 > hannu=# update seq set max_value = 99; > UPDATE 1 > hannu=# update pg_class set relkind = 'S' where relname = 'seq'; > UPDATE 1 > hannu=# select * from seq; > sequence_name | last_value | increment_by | max_value | min_value | > cache_value | log_cnt | is_cycled | is_called > ---------------+------------+--------------+-----------+-----------+-------------+---------+-----------+----------- > seq | 1 | 1 | 99 | 1 > | 1 | 1 | f | f That makes me wonder. If sequense is treated like a single column single row table and it's value is guarenteed to be increasing even in case of aborted transaction, is it correct to say that postgresql already has nested transactions, albeit dormant? ByeShridhar -- Zero Defects, n.: The result of shutting down a production line.
Shridhar Daithankar kirjutas K, 04.12.2002 kell 20:51: > On 4 Dec 2002 at 20:41, Hannu Krosing wrote: > > hannu=# update seq set max_value = 99; > > ERROR: You can't change sequence relation seq > > hannu=# update pg_class set relkind = 'r' where relname = 'seq'; > > UPDATE 1 > > hannu=# update seq set max_value = 99; > > UPDATE 1 > > hannu=# update pg_class set relkind = 'S' where relname = 'seq'; > > UPDATE 1 > > hannu=# select * from seq; > > sequence_name | last_value | increment_by | max_value | min_value | > > cache_value | log_cnt | is_cycled | is_called > > ---------------+------------+--------------+-----------+-----------+-------------+---------+-----------+----------- > > seq | 1 | 1 | 99 | 1 > > | 1 | 1 | f | f I just discovered that changing these numbers does not change how the sequence behaves ;( Even after restarting the backend! Sorry! > That makes me wonder. If sequense is treated like a single column single row > table and it's value is guarenteed to be increasing even in case of aborted > transaction, is it correct to say that postgresql already has nested > transactions, albeit dormant? No. Sequences live outside of transactions. I have no idea why there is also a ingle column single row table created. The output of \d command is also weird, for all sequences I get: hannu=# \d seq Sequence "public.seq" Column | Type ---------------+---------sequence_name | namelast_value | bigintincrement_by | bigintmax_value | bigintmin_value | bigintcache_value | bigintlog_cnt | bigintis_cycled | booleanis_called | boolean with only the Sequence name changing ... --------------- Hannu
On Wed, 2002-12-04 at 09:06, Oliver Elphick wrote: > On Wed, 2002-12-04 at 12:29, raja kumar thatte wrote: > > Hai friends, > > I have a sequence called raj_seq with max value 3000. > ... > > now i wanted to increase the max value of the raj_seq > > to 9999999. > > How to do this change? > > If i drop and recreate the raj_seq, then i have to > > recreate the table and all triggers working on that > > table.But it is not an acceptable solution. > > So with out droping raj_seq , how do I solve this > > problem. > > Unfortunately there doesn't seem to be any easy way to do this. There > is no ALTER SEQUENCE command and you can't use UPDATE on a sequence. > > Hackers: Could this be a TODO item for 7.4? I'm hoping to do that one sooner than later, unless Neil beats me to it. -- Rod Taylor <rbt@rbt.ca> PGP Key: http://www.rbt.ca/rbtpub.asc
Around 20:41 on Dec 4, 2002, Hannu Krosing said:
What's wrong with this:
dustin=# create sequence test_seq;
CREATE SEQUENCE
dustin=# select nextval('test_seq');
nextval
---------
1
(1 row)
dustin=# select setval('test_seq', 9999);
setval
--------
9999
(1 row)
dustin=# select nextval('test_seq');
nextval
---------
10000
(1 row)
# Oliver Elphick kirjutas K, 04.12.2002 kell 19:06:
# > On Wed, 2002-12-04 at 12:29, raja kumar thatte wrote:
# > > Hai friends,
# > > I have a sequence called raj_seq with max value 3000.
# > ...
# > > now i wanted to increase the max value of the raj_seq
# > > to 9999999.
# > > How to do this change?
# > > If i drop and recreate the raj_seq, then i have to
# > > recreate the table and all triggers working on that
# > > table.But it is not an acceptable solution.
# > > So with out droping raj_seq , how do I solve this
# > > problem.
# >
# > Unfortunately there doesn't seem to be any easy way to do this. There
# > is no ALTER SEQUENCE command and you can't use UPDATE on a sequence.
# >
# > Hackers: Could this be a TODO item for 7.4?
#
# This seems to work - as an example why we need the TODO ;)
#
# hannu=# update seq set max_value = 99;
# ERROR: You can't change sequence relation seq
# hannu=# update pg_class set relkind = 'r' where relname = 'seq';
# UPDATE 1
# hannu=# update seq set max_value = 99;
# UPDATE 1
# hannu=# update pg_class set relkind = 'S' where relname = 'seq';
# UPDATE 1
# hannu=# select * from seq;
# sequence_name | last_value | increment_by | max_value | min_value |
# cache_value | log_cnt | is_cycled | is_called
# ---------------+------------+--------------+-----------+-----------+-------------+---------+-----------+-----------
# seq | 1 | 1 | 99 | 1
# | 1 | 1 | f | f
# (1 row)
#
# I can't really recommend it, because it may (or may not ;) have some
# unwanted behaviours as well;
#
#
# >
# > The easiest way to do this at present is probably to dump the database,
# > edit the dump to change the sequence max_value and then recreate the
# > database from the edited dump. I presume you used CREATE SEQUENCE in
# > order to get such a low max_value. If it were created from a SERIAL
# > datatype, you would also have to edit the table definition to use a
# > pre-created sequence. There is no means of specifying a max_value using
# > SERIAL.
# --
# Hannu Krosing <hannu@tm.ee>
#
# ---------------------------(end of broadcast)---------------------------
# TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org
#
#
--
SPY My girlfriend asked me which one I like better.
pub 1024/3CAE01D5 1994/11/03 Dustin Sallings <dustin@spy.net>
| Key fingerprint = 87 02 57 08 02 D0 DA D6 C8 0F 3E 65 51 98 D8 BE
L_______________________ I hope the answer won't upset her. ____________
On Wed, Dec 04, 2002 at 09:33:52AM -0800, Dustin Sallings wrote:
> Around 20:41 on Dec 4, 2002, Hannu Krosing said:
>
> What's wrong with this:
>
> dustin=# create sequence test_seq;
> CREATE SEQUENCE
> dustin=# select nextval('test_seq');
> nextval
> ---------
> 1
> (1 row)
>
> dustin=# select setval('test_seq', 9999);
> setval
> --------
> 9999
> (1 row)
>
> dustin=# select nextval('test_seq');
> nextval
> ---------
> 10000
> (1 row)
Dustin --
The thread here is about how to raise the *max* value for the sequence,
not how to set the current value higher. The sequence in question was
created with a too-low maximum value (see help on CREATE SEQUENCE for
options); the user now wants to raise it.
- J.
--
Joel BURTON | joel@joelburton.com | joelburton.com | aim: wjoelburton
Independent Knowledge Management Consultant
Around 12:44 on Dec 4, 2002, Joel Burton said:
# The thread here is about how to raise the *max* value for the sequence,
# not how to set the current value higher. The sequence in question was
# created with a too-low maximum value (see help on CREATE SEQUENCE for
# options); the user now wants to raise it.
Ahh, OK. Seemed too obvious. :)
--
SPY My girlfriend asked me which one I like better.
pub 1024/3CAE01D5 1994/11/03 Dustin Sallings <dustin@spy.net>
| Key fingerprint = 87 02 57 08 02 D0 DA D6 C8 0F 3E 65 51 98 D8 BE
L_______________________ I hope the answer won't upset her. ____________
On Wed, 2002-12-04 at 17:33, Dustin Sallings wrote:
> What's wrong with this:
>
> dustin=# create sequence test_seq;
> CREATE SEQUENCE
> dustin=# select nextval('test_seq');
> nextval
> ---------
> 1
> (1 row)
>
> dustin=# select setval('test_seq', 9999);
> setval
> --------
> 9999
> (1 row)
>
> dustin=# select nextval('test_seq');
> nextval
> ---------
> 10000
> (1 row)
It's not the issue. The original question was how to change the upper
limit of the sequence's range, not its current value.
junk=# create sequence foo_seq maxvalue 3000;
CREATE SEQUENCE
junk=# select nextval('foo_seq');
nextval
---------
1
(1 row)
junk=# select setval('foo_seq', 999999);
ERROR: foo_seq.setval: value 999999 is out of bounds (1,3000)
--
Oliver Elphick <olly@lfix.co.uk>
LFIX Limited
Oliver Elphick wrote:
> On Wed, 2002-12-04 at 12:29, raja kumar thatte wrote:
> > Hai friends,
> > I have a sequence called raj_seq with max value 3000.
> ...
> > now i wanted to increase the max value of the raj_seq
> > to 9999999.
> > How to do this change?
> > If i drop and recreate the raj_seq, then i have to
> > recreate the table and all triggers working on that
> > table.But it is not an acceptable solution.
> > So with out droping raj_seq , how do I solve this
> > problem.
>
> Unfortunately there doesn't seem to be any easy way to do this. There
> is no ALTER SEQUENCE command and you can't use UPDATE on a sequence.
Gee, I thought they could just update the sequence table, but I see:
test=> update yy set max_value = 100;
ERROR: You can't change sequence relation yy
> Hackers: Could this be a TODO item for 7.4?
Added to TODO:
* Add ALTER SEQUENCE to modify min/max/increment/cache/cycle values
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073