Re: Please clarify with regard to Renaming a Sequence - Mailing list pgsql-hackers

Postgres manages sequences using DEFAULT, which means that if you insert
a row with the sequence column set to DEFAULT, or omit the row in the
insert, then the default value will be inserted. This is usually
nextval('sequence_name'). There is no underlying magic other than this.
So, as long as you ensure that the new sequence you create has the
correct start value, and you change the default constraint on the column
you are free to do as you wish with the sequences.

Have a look at what pg_dump does with sequences and tables.

Dave

On Sun, 2003-03-23 at 23:20, Anand B Kumar wrote:
> Dear Dave,
> 
> Thanx a lot for your help.  But still, the doubt lies, whether we can change
> the property of a table which has bulk recods on it!!!  Does pgsql support
> that??  Even though u alter the name of the sequence, we need to change the
> sequence name ( meaning the property in the default field) in the altered
> table also, which should now point to the new altered sequence.
> 
> Please advice
> thanx
> Andy
> 
> 
> ----- Original Message -----
> From: "Dave Cramer" <dave@fastcrypt.com>
> To: "Anand B Kumar" <akumar@addr.com>
> Cc: <pgsql-general@postgresql.org>; <pgsql-hackers@postgresql.org>
> Sent: Saturday, March 22, 2003 8:42 PM
> Subject: Re: [HACKERS] Please clarify with regard to Renaming a Sequence
> 
> 
> > >From what I can see the sequence name is not changed when you rename a
> > table
> >
> > test=# alter table fooseq rename to fooseq1;
> > ALTER TABLE
> > test=# \d fooseq1
> >                           Table "public.fooseq1"
> >  Column |  Type   |                       Modifiers
> > --------+---------+-------------------------------------------------------
> -
> >  id     | integer | not null default
> > nextval('public.fooseq_id_seq'::text)
> >
> > so everything should work as expected.
> >
> > Dave
> >
> > On Fri, 2003-03-21 at 09:38, Anand B Kumar wrote:
> > > Dear Sirs,
> > >
> > > We are working on Postgresql for one of our on going project.  We have
> > > come across a situation as mentioned below.
> > >
> > > 1. We have to create a table with sequence dynamically from the front
> > > end ( through a JSP code)
> > > 2. An option for the user is given to change the name of the table in
> > > the front end.  During this process, we change the name of the table
> > > and its relative sequence too.  But the table which was first created
> > > with a sequence has its property written in its property field.  Now
> > > if we change that property in that field, will the sequence gets
> > > disturbed??
> > >
> > > For say, I create a table 'addrtech'  which has two fields, empid and
> > > empname
> > > 2. The emp id has a sequence created dynamically. so a sequence
> > > name   addrtech_empid_seq  is created.
> > > 3. The field empid  in addrtech has in its DEFAULT column as
> > > " nextval('"addrtech_empid_seq"'::text) "
> > > 4. Now I rename addrtech to addrtechnology
> > > 5.  So the table is altered
> > > 6. The sequence is also altered as addrtechnology_empid_seq and the
> > > new table is addrtechnology
> > >
> > > But the doubt now is the field which has the sequence i.e the empid
> > > which has nextval('"addrtech_empid_seq"'::text) .  The property if
> > > changed to  nextval('"addrtechnology_empid_seq"'::text) will the
> > > seqeunce remain the same.  Meaning if it had some few million records
> > > in the orginial table addrtech and if additional data is entere to
> > > addrtechnology will the sequence continue.
> > >
> > > Please clarify this query of mine at the earliest so that we can
> > > incorporate the same in our codes
> > >
> > >
> > > Your early reply is solicitated
> > >
> > > regards
> > > Andy
> > >
> > >
> > >
> > > ______________________________________________________________________
> > > Upgrade Your Email - Click here!
> > --
> > Dave Cramer <dave@fastcrypt.com>
> > Cramer Consulting
> >
> >
> 
> 
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-- 
Dave Cramer <dave@fastcrypt.com>
Cramer Consulting