Thanks for your comments !

Right. As you pointed out, Sigres cannot recover if UPS fails.
Therefore, I think currently Sigres cannot be used for mission critical
Sigres keeps data integrity *only when* UPS works.

On the other hand, some users such as researchers of sensor networks
would like store
and analyze 10^6 Hz sensor data insertions in real-time, and obviously
research usages are not mission critical. Thus Sigres may be accepted
for researchers, but I have no prospect now since I have just started to
distributing Sigres for research institutes in Japan.

BTW, Joshua, could you please let me know or give me any pointers for
the reason why fsync=off option exists on PostgreSQL although PostgreSQL
developers does not allow sacrificing data integrity ?
If the reason is famous and clear in the community, I am sorry for
bothering you.

-- Hideyuki

Joshua D. Drake wrote:
> Hideyuki Kawashima wrote:
>> Hello PostgreSQL Hackers,
>> I have made a modification of PostgreSQL which accelerates INSERT/UPDATE 
>> using UPS. The name of the software is "Sigres", and the philosophy is 
>> considering a battery supplied memory as a persistent device instead of a 
>> disk. You can download Sigres from .
>> In the maximum case, Sigres is 7 times faster than PostgreSQL default 
>> (fsync=on) in my environment (CoreDuo 2.66GHz, UDMA/133), and it is also 10% 
>> faster than PostgreSQL without fsync (fsync=off).
> Interesting and what happens when the UPS fails? My main concern is that
> one of the purposes of PostgreSQL is data integrity. I am all for every
> performance enhancement we can achieve, that does *not* sacrifice that.
> Sincerely,
> Joshua D. Drake
>> The magic lies in usually skipping XLogWrite() and ignoring WALWriteLock. 
>> The exceptions are XLogWrite() calls from AdvanceXLInsertBuffer(). In 
>> addition, in XLogFileClose() issue_xlog_fsync() before close(). (In this 
>> point, Sigres is different from just simply setting fsync=off.)
>> Although I think Sigres can be considered as one of the future directions of 
>> PostgreSQL, I do not know whether this software can be accepted or not. 
>> Could you please give me some comments ?
>> Best Regards,
>> -- Hideyuki Kawashima 
>> Assistant Professor, University of Tsukuba
>> ---------------------------(end of broadcast)---------------------------
>> TIP 1: if posting/reading through Usenet, please send an appropriate
>>        subscribe-nomail command to [EMAIL PROTECTED] so that your
>>        message can get through to the mailing list cleanly

---------------------------(end of broadcast)---------------------------
TIP 6: explain analyze is your friend

Reply via email to