I think it would be great if it where an option. Perhaps even a sandbox implementation that could wrap or replace a few classes. Maybe that complicates things too much, but that way you could just not use the transaction system if you where on NFS (if that ends up being a problem) or you didn't want to pay a performance cost.

Maybe a Derby guy would pitch in.

Chris Hostetter wrote:
: This is simple not true. See FileDescriptor.sync().
: : There are several options, but normally it is used so that when close
: completes, all data must be on disk. This is a much slower way to write data.
: It is very common in database systems when committing the log file.

Ok. I'll certainly take your word for it ... i've been trusting the docs for [File]OutputStream.flush()...

If the intended destination of this stream is an abstraction provided by the underlying operating system, for example a file, then flushing the stream guarantees only that bytes previously written to the stream are passed to the operating system for writing; it does not guarantee that they are actually written to a physical device such as a disk drive.

I haven't looked at the internals of FileOutputStream or FileDescriptor on any particular platforms to see how exactly they work, but if dealing with the FD directly and using FD.sync() the magic bullet then I'd love to see a patch that uses it in FSDirectory.

I assume the SyncFailedException it throws is rare? If it is always thrown when using things like NFS that may be a show stopper for using sync() in Lucene ... many people have jumped through a lot of hoops this past year to get Lucene working on NFS; I'd hate to see all that work go out the window in an effort to make Lucene ACID. (I suspect there are more users interested in using Lucene on NFS then on using it as a transactional data store)

Throws:
SyncFailedException - Thrown when the buffers cannot be flushed, or because the system cannot guarantee that all the buffers have been synchronized with physical media.

-Hoss


---------------------------------------------------------------------
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]

Reply via email to