Decibel! írta:
> On Mar 25, 2008, at 11:40 AM, Zoltan Boszormenyi wrote:
>> All of them? PostgreSQL allow multiple SERIALs to be present,
>> the standard allows only one IDENTITY column in a table.
>> And what about this case below?
>>
>> CREATE TABLE t1 (id1 serial, ...);
>> ALTER SEQUENCE seq_t1_id1 RESTART WITH 5432 CYCLE;
>>
>> or the equivalent
>>
>> CREATE SEQUENCE seq_t1_id1 START WITH 5432 CYCLE;
>> CREATE TABLE t1 (id1 serial, ...);
>> ALTER SEQUENCE seq_t1_id1 OWNED BY t1.id1;
>>
>> PostgreSQL doesn't keep the START WITH information.
>> But it should to perform a "restart" on the sequence,
>> using the minval in this case wouldn't be correct.
>
>
> I think you misunderstand what ALTER SEQUENCE RESTART does; it only
> changes the current value of the sequence.
I didn't misunderstood, I know that. I quoted both
because (currently) CREATE SEQUENCE ... START WITH does the same.
zozo=> create sequence seq1 start with 327;
CREATE SEQUENCE
zozo=> select * from seq1;sequence_name | last_value | increment_by | max_value |
min_value | cache_value | log_cnt | is_cycled | is_called
---------------+------------+--------------+---------------------+-----------+-------------+---------+-----------+-----------seq1
| 327 | 1 | 9223372036854775807
| 1 | 1 | 1 | f | f
(1 row)
Note the difference between "min_value" and "last_value".
Using the standard syntax of
CREATE TABLE ( id integer IDENTITY GENERATED ALWAYS AS (START WITH 327), ...
);
and assuming you use the existing sequence infrastructure
there's a problem with TRUNCATE ... RESTART IDENTITY;
Where is the info in the sequence to provide restarting with
the _original_ start value?
--
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Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
http://www.postgresql.at/
