Re: Hibernate, web application and only one sequence for all primary keys

Above all, do not fret about whether or not it is "cool to lose" some
ids. There are plenty of integers; the ids need not be consecutive. I
don't think Grails requires a single sequence source and I know
hibernate does not. Hibernate will allow one to inject any sequence/id
generator you wish to use (including one which generates UUIDs).

rawi wrote:
> Leo Mannhart wrote:
>
>> Caveat: If you use the standard sequence generator in hibernate, it is
>> not using the postgres-sequence in the "usual" manner. hibernate itself
>> caches 50 ID's as sequence numbers by default. This means, hibernate
>> only does a select on the database sequence every 50 numbers. it
>> multyplies the database sequence by 50 to get the "real" sequence
>> number. it generates the sequence numbers in blocks of 50 numbers or
>> according to the sequence cache size.
>> That said, you would probably not see any performance bottlenecks
>> because of the sequence number generator in the database, even with
>> thousands of inserts per second.
>>
>>
>
> Hi Leo, thank you for the explanation!
>
> I don't know if it is that cool to lose up to 50 IDs on each session-end of
> Hibernate...
> And what do you suppose it would happen, if I set the cache size of
> Hibernate's own sequence (after generation) by hand to 1 instead of 50? I
> wouldn't need tausends of inserts per second...
>
> Kind regards, Rawi
>
>