Joshua, 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 applications. 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 http://sourceforge.jp/projects/sigres/ . >> >> 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
