On Feb 7, 2008 7:22 AM, robert engels <[EMAIL PROTECTED]> wrote: > That doesn't help, with lazy writing/buffering by the OS, there is no > guarantee that if the last written block is ok, that earlier blocks > in the file are.... > > The OS/drive is going to physically write them in the most efficient > manner. Only after a sync would this hold true (which is what we are > trying to avoid).
Hi, how about asynchronous commit? i.e. use a thread to sync the data. We only need to make sure that all data are written to the storage before the next operation? > > > On Feb 6, 2008, at 5:15 PM, DM Smith wrote: > > > > > On Feb 6, 2008, at 5:42 PM, Michael McCandless wrote: > > > >> > >> robert engels wrote: > >> > >>> Do we have any way of determining if a segment is definitely OK/ > >>> VALID ? > >> > >> The only way I know is the CheckIndex tool, and it's rather slow (and > >> it's not clear that it always catches all corruption). > > > > Just a thought. It seems that the discussion has revolved around > > whether a crash or similar event has left the file in an > > inconsistent state. Without looking into how it is actually done, > > I'm going to guess that the writing is done from the start of the > > file to its end. That is, no "out of order" writing. > > > > If this is the case, how about adding a marker to the end of the > > file of a known size and pattern. If it is present then it is > > presumed that there were no errors in getting to that point. > > > > Even with out of order writing, one could write an 'INVALID' marker > > at the beginning of the operation and then upon reaching the end of > > the writing, replace it with the valid marker. > > > > If neither marker is found then the index is one from before the > > capability was added and nothing can be said about the validity. > > > > -- DM > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > -- Best regards, Andrew Zhang db4o - database for Android: www.db4o.com http://zhanghuangzhu.blogspot.com/
