On Mar 20, 2007, at 12:48 PM, John Siracusa wrote:
> On 3/20/07, Derek Watson <[EMAIL PROTECTED]> wrote:
>> Is it possible to get sequence support in RDBO? I know that
>> sequences are
>> supported for primary key generation, but I have a few cases where
>> they are
>> used for non-keyed columns
>
> What would this support look like? How would the sequence be
> specified, and how would it behave on insert, update, etc.?
>
>> But since next_value_in_sequence is not documented, I am worrying
>> that it's
>> interface may change or disappear.
>
> It almost certainly won't disappear and may become part of the public
> API eventually.
>
> -John
I'll second wanting support too :)
On Mar 20, 2007, at 1:11 PM, Derek Watson wrote:
> I suppose my use of serial/sequence columns is too specific to
> bother adding to the API, but basically
>
> some_seq_column => { type => 'serial', not_null => 1, sequence =>
> 'some_seq' },
That makes perfect sense to me. although that looks like what is in
there for oracle already
I'd actually like to see sequence classes
Rose::DB::Object::Metadata::Sequence
Which lets us map sequences to rose objects , and vice versa
I'd like to be able to call
my $seq= MyApp::Rose::DB::Object::Sequence1->new();
my $curval= $seq->curval;
my $nextval= $seq->nextval;
my $lastval = $seq->lastval;
getting that to work with all dbs might be a pain though.
I'll chime in with the Postgres compatibility -- if anyone wants this
support too, please comment on MySQL , SQLite, Oracle, etc
Postgres:
Create Sequence
http://www.postgresql.org/docs/8.2/interactive/sql-createsequence.html
Compatibility
CREATE SEQUENCE conforms to the SQL standard, with the
following
exceptions:
The standard's AS <data type> expression is not
supported.
Obtaining the next value is done using the nextval()
function
instead of the standard's NEXT VALUE FOR expression.
The OWNED BY clause is a PostgreSQL extension.
Alter Sequence
http://www.postgresql.org/docs/8.2/interactive/sql-altersequence.html
Compatibility
ALTER SEQUENCE conforms to the SQL standard, except for the
OWNED
BY and SET SCHEMA clauses, which are PostgreSQL extensions.
Drop Sequence
http://www.postgresql.org/docs/8.2/interactive/sql-dropsequence.html
Compatibility
DROP SEQUENCE conforms to the SQL standard, except that the
standard only allows one sequence to be dropped per command, and
apart from the IF EXISTS option, which is a PostgreSQL extension.
Sequence Manipulation Functions
http://www.postgresql.org/docs/8.2/interactive/functions-sequence.html
currval(regclass) bigint Return value most recently
obtained with
nextval for specified sequence
nextval(regclass) bigint Advance sequence and return new
value
setval(regclass, bigint) bigint Set sequence's current value
setval(regclass, bigint, boolean) bigint Set sequence's
current
value and is_called flag
lastval - Return the value most recently returned by nextval in
the
current session. This function is identical to currval, except that
instead of taking the sequence name as an argument it fetches the
value of the last sequence that nextval was used on in the current
session. It is an error to call lastval if nextval has not yet been
called in the current session.
Important: To avoid blocking of concurrent transactions that
obtain
numbers from the same sequence, a nextval operation is never rolled
back; that is, once a value has been fetched it is considered used,
even if the transaction that did the nextval later aborts. This means
that aborted transactions may leave unused "holes" in the sequence of
assigned values. setval operations are never rolled back, either.
// Jonathan Vanasco
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