Hi, > But there are other technologies that allow fast syncs: SSDs, SANs, > some exotic controllers and HDDs with batteries. Some of them > guarantee true syncs.
Yes. In that case, you could use WRITE_DELAY of 0 and a file access mode "rws" or "rwd". I think this is what Apache Derby uses. Apache Derby doesn't call FileDescriptor.sync() for each commit either. See also http://h2database.com/html/performance.html#performance_comparison > Is my understanding correct that CHECKPOINT SYNC will flush not only > log buffers but also dirty data blocks? If yes, then it will slow down > performance of commit. Yes, that's true. > Also, a pair COMMIT,CHECKPOINT SYNC is not atomic. > It may create uncertainty. There is anyway some kind of uncertainty if there is a crash *within* commit, even if each commit itself is 100% guaranteed atomic. Because you couldn't tell where exactly within the commit the crash occurred (just before commit returned, or at the beginning of the commit call). Regards, Thomas -- You received this message because you are subscribed to the Google Groups "H2 Database" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/h2-database?hl=en.
