It's complicated.
In 2.3, you can use IW.flush to write docs to disk. But that method
will be deprecated in 2.4 and replaced with commit. Or, you can close.
If application (jvm) dies or killed, the index will be fine but won't
have any un-flushed buffered docs.
If machine dies (os crashes, power cord pulled) then there is a real
risk that the index will become corrupt. This is because Lucene has
never explicitly sync()'d the files to ensure they are on stable
storage. LUCENE-1044 fixes that (adds syncs).
Mike
<[EMAIL PROTECTED]> wrote:
OK, so there is nothing in 2.3 besides IndexWriter.close to ensure
that the
docs are written to disk and that the index will survive an
application /
machine death?
-----Original Message-----
From: Michael McCandless [mailto:[EMAIL PROTECTED]
Sent: Freitag, 8. Februar 2008 19:34
To: java-user@lucene.apache.org
Subject: Re: IndexWriter: setRAMBufferSizeMB
Well ... every time the RAM buffer is full, a new segment is flushed
to the Directory, but that is not necessarily a "commit" in that
an IndexReader would see the new segment, nor, that the segment would
survive if the machine suddenly crashed.
You should't rely on when specifically IndexWriter makes its changes
visible to readers. The best way to be sure is to close the writer.
There is work underway now, in this issue:
https://issues.apache.org/jira/browse/LUCENE-1044
that will add an explicit "commit" call, which you would use to 1)
make the changes visible to readers, and 2) sync the index such that
if the machine crashed (after commit returns) then your changes as of
the commit will survive. But it's not committed yet ... it will
be in
2.4.
One way for a reader to check if a new commit has happened is to
call the isCurrent method. Maybe that helps?
Mike
<[EMAIL PROTECTED]> wrote:
Hi,
if I understand this property correctly every time the ram buffer
is full it
gets automaticaly written to disk. Something like a commit in a
database.
Thus if my application dies, all docs in the buffer get lost. Right?
If so, is there any event/callback etc. which informs my
application that
such a commit happend?
Thank you.
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