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https://issues.apache.org/jira/browse/LUCENE-2386?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12855131#action_12855131
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Shai Erera commented on LUCENE-2386:
------------------------------------
Took a look at IndexFileDeleter, and located to offending code segment which is
responsible for the IndexCorruptException:
{code}
if (currentCommitPoint == null) {
// We did not in fact see the segments_N file
// corresponding to the segmentInfos that was passed
// in. Yet, it must exist, because our caller holds
// the write lock. This can happen when the directory
// listing was stale (eg when index accessed via NFS
// client with stale directory listing cache). So we
// try now to explicitly open this commit point:
SegmentInfos sis = new SegmentInfos();
try {
sis.read(directory, segmentInfos.getCurrentSegmentFileName(), codecs);
} catch (IOException e) {
throw new CorruptIndexException("failed to locate current segments_N
file");
}
{code}
Looks like this code protects against a real problem, which was raised on the
list a couple of times already - stale NFS cache. So I'm reluctant to remove
that check ... thought I still think we should differentiate between a newly
created index on a fresh Directory, to a stale NFS problem. Maybe we can pass a
boolean isNew or something like that to the ctor, and if it's a new index and
the last commit point is missing, IFD will not throw the exception, but
silently ignore that? So the code would become something like this:
{code}
if (currentCommitPoint == null && !isNew) {
....
}
{code}
Does this make sense, or am I missing something?
> IndexWriter commits unnecessarily on fresh Directory
> ----------------------------------------------------
>
> Key: LUCENE-2386
> URL: https://issues.apache.org/jira/browse/LUCENE-2386
> Project: Lucene - Java
> Issue Type: Bug
> Components: Index
> Reporter: Shai Erera
> Assignee: Shai Erera
> Fix For: 3.1
>
>
> I've noticed IndexWriter's ctor commits a first commit (empty one) if a fresh
> Directory is passed, w/ OpenMode.CREATE or CREATE_OR_APPEND. This seems
> unnecessarily, and kind of brings back an autoCommit mode, in a strange way
> ... why do we need that commit? Do we really expect people to open an
> IndexReader on an empty Directory which they just passed to an IW w/
> create=true? If they want, they can simply call commit() right away on the IW
> they created.
> I ran into this when writing a test which committed N times, then compared
> the number of commits (via IndexReader.listCommits) and was surprised to see
> N+1 commits.
> Tried to change doCommit to false in IW ctor, but it got IndexFileDeleter
> jumping on me .. so the change might not be that simple. But I think it's
> manageable, so I'll try to attack it (and IFD specifically !) back :).
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