Re: [HACKERS] Sequences....

It has been put on hold, I'll begin/continue working on it when we are done with
the beta :)

-Ryan

> Can I ask where we are with this.
>
> > Hello hackers...
> >
> > I've spent the last couple of evening tracing through the drop
table/sequence
> > code trying to figure out the best to drop the sequence when the table is
> > dropped.
> >
> > Here is what I am proposing to do. I just wanted to throw out my idea and
get
> > some feedback since I am just beginning to understand how the backend works.
> >
> > Take the following example:
> > CREATE TABLE foo (i SERIAL, t text);
> >
> > This creates table foo, index foo_i_key, and the sequence foo_i_seq.
> >
> > The sequence ocuppies three of the system tables: pg_class, pg_attribute,
and
> > pg_attrdef. When the table gets dropped, the table foo and foo_i_key are
> > removed. The default portion of the sequence is also removed from the
> > pg_attrdef system table, because the attrelid matches the table's oid.
> >
> > I believe this is incorrect ... I think the attrelid should match the
seqences
> > oid instead of the table's oid to prevent the following error:
> >
> > ryan=> CREATE TABLE foo (i SERIAL, t text);
> > NOTICE: CREATE TABLE will create implicit sequence foo_i_seq for SERIAL
column
> > foo.i
> > NOTICE: CREATE TABLE/UNIQUE will create implicit index foo_i_key for table
foo
> > CREATE
> >
> > ryan=> \d
> >
> > Database = ryan
> > +------------------+----------------------------------+----------+
> > | Owner | Relation | Type |
> > +------------------+----------------------------------+----------+
> > | rbrad | foo | table |
> > | rbrad | foo_i_key | index |
> > | rbrad | foo_i_seq | sequence |
> > +------------------+----------------------------------+----------+
> >
> > ryan=> \d foo;
> >
> > Table = foo
> >
+----------------------------------+----------------------------------+-------+
> > | Field | Type |
Length|
> >
+----------------------------------+----------------------------------+-------+
> > | i | int4 not null default nextval('f |
4 |
> > | t | text |
var |
> >
+----------------------------------+----------------------------------+-------+
> > Index: foo_i_key
> >
> > ryan=> drop sequence foo_i_seq;
> > DROP
> >
> > ryan=> \d
> >
> > Database = ryan
> > +------------------+----------------------------------+----------+
> > | Owner | Relation | Type |
> > +------------------+----------------------------------+----------+
> > | rbrad | foo | table |
> > | rbrad | foo_i_key | index |
> > +------------------+----------------------------------+----------+
> > ryan=> \d foo;
> >
> > Table = foo
> >
+----------------------------------+----------------------------------+-------+
> > | Field | Type |
Length|
> >
+----------------------------------+----------------------------------+-------+
> > | i | int4 not null default nextval('f |
4 |
> > | t | text |
var |
> >
+----------------------------------+----------------------------------+-------+
> > Index: foo_i_key
> >
> > ryan=> insert into foo (t) values ('blah');
> > ERROR: foo_i_seq.nextval: sequence does not exist
> >
> > ryan=>
> >
> > This looks pretty easy to fix.
> >
> > Back to my origional point .. I think we need another system table to map
the
> > sequence oid to the table's oid. I've noticed this done with the
inheritance,
> > indexes, etc ... but I don't see a pg_sequence table.
> >
> > I would be glad to try and finish this in the next couple of evenings if
this
> > looks like the correct approach to the problem, otherwise could someone
point me
> > in the right direction :)
> >
> > Thanks,
> > -Ryan
> >
> >
>
>
> --
> Bruce Momjian | http://www.op.net/~candle
> maillist(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
> + If your life is a hard drive, | 830 Blythe Avenue
> + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
>