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List:       lucene-dev
Subject:    [jira] Commented: (LUCENE-1314) IndexReader.reopen(boolean force)
From:       "Michael McCandless (JIRA)" <jira () apache ! org>
Date:       2008-06-29 9:51:45
Message-ID: 603629813.1214733105331.JavaMail.jira () brutus
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    [ https://issues.apache.org/jira/browse/LUCENE-1314?page=com.atlassian.jira.plugin \
.system.issuetabpanels:comment-tabpanel&focusedCommentId=12609072#action_12609072 ] 

Michael McCandless commented on LUCENE-1314:
--------------------------------------------

bq. It is possible to have SegmentReader implement if deletes occur to an earlier \
IndexReader and a flush is tried it fails, rather than fail in a newer IndexReader \
like it would now. This would require keeping track of later IndexReaders which is \
something Ocean does outside of IndexReader.

I think this is tricky, since SegmentReader doesn't explicitly track whether there is \
a "cloned" reader out there.  As things stand now, there is no such thing as a cloned \
reader, and so the only way that another SegmentReader is out there is if there have \
been commits to the index, in which case isCurrent() returns false and the old reader \
will not allow deletes to be performed.  I suppose we could look at the refCount of \
the IndexReader: any reader that has been cloned and not yet closed will have a \
refCount > 1, whereas the last reader returned from a clone() call will have refCount \
1.

So unless we try to track this, when there are N clones out there, any one of them \
will be allowed to grab the write lock when a change (deletion or setNorm) is \
attempted, thus preventing all the other clones (and all readers open on previous \
commits) from making changes.

> IndexReader.reopen(boolean force)
> ---------------------------------
> 
> Key: LUCENE-1314
> URL: https://issues.apache.org/jira/browse/LUCENE-1314
> Project: Lucene - Java
> Issue Type: New Feature
> Components: Index
> Affects Versions: 2.3.1
> Reporter: Jason Rutherglen
> Assignee: Michael McCandless
> Priority: Minor
> Attachments: lucene-1314.patch, lucene-1314.patch, lucene-1314.patch
> 
> 
> Based on discussion http://www.nabble.com/IndexReader.reopen-issue-td18070256.html. \
> The problem is reopen returns the same reader if there are no changes, so if docs \
> are deleted from the new reader, they are also reflected in the previous reader \
> which is not always desired behavior.

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