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From dag.wan...@oracle.com (Dag H. Wanvik)
Subject Re: Autocounter/Sequqnce-Numbers
Date Sun, 22 May 2011 22:03:05 GMT
Tim Dudgeon <tdudgeon@informaticsmatters.com> writes:

> There are some other things here that might deserve some comment:
> http://www.h2database.com/html/features.html#comparison
> e.g. performance of embeded derby is slow!

Without qualification, such wholesale statements are close to
meaningless, IMHO.  It's not long ago since we saw a report on this list
of a case where Derby outperformed H2 on scalability (performance with
multiple threads). The only way to know is to test a particular
scenario. For example, you could Derby in-memory if you didn't care
about durability. One can even turn off synchronous logging to disk if
database consistency after a crash isn't an issue. One can lower the
default isolation mode to avoid lock contention etc. It all depends on
the use case.


> Tiim
> On 18/05/2011 16:05, Malte.Kempff@de.equens.com wrote:
>> Hi to all,
>> in http://www.h2database.com/html/features.html#feature_list I found
>> this particular statement to above topic:
>> *Sequence*and autoincrement columns, computed columns (can be used for
>> function based indexes)
>> Later on is a matrix that shows some RDBMs in releation to some features
>> where it is denied that Derby supports sequences.
>> So what is actually the case? And if Derby supports running numbers (in
>> Oracle they are called /sequences/, in Microsoft DBs the are often
>> called /auto counters/) how are they to be used.
>> Thanks in advance for any hint
>> Malte

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