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From "Hoss Man (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-743) IndexReader.reopen()
Date Sat, 21 Jul 2007 00:27:06 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-743?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12514379
] 

Hoss Man commented on LUCENE-743:
---------------------------------


> Yeah we could do that. However, this might not be so easy to implement.
> For example, if a user creates a MultiReader instance and adds whatever
> subreaders, we would have to recursively refresh the underlying readers.
> But if the MultiReader was created automatically by IndexReader.open() just
> calling refresh on the subreaders is not enough. New SegmentReaders have to
> be opened for new segments. 

...this being the curse that is MultiReader -- it can serve two very differenet purposes.
 

You seem to have already solved the multisegments in a single directory approach, the MultiReader
over many subreader part actually seems much easier to me (just call your open method on all
of the subreaders) the only tricky part is detecting which behavior should be used when. This
could be driven by a simple boolean property of MultiReader indicating whether it owns it's
directory and we need to look for new segments or not -- in which case we just need to refresh
the subreaders.  (My personal preference would be to change MultiReader so "this.directory"
is null if it was open over several other subReaders, right now it's just assigned to the
first one arbitrarily, but there may be other consequences of changing that)

Incidentally: I don't think it's crucial that this be done as a recursive method.  the same
approach i describe could be added to  static utility like what you've got, I just think that
if it's possible to do it recursively we should so that  *if* someone does write their own
MultiReader or SegmentReader subclass they can still benefit from any core reopening logic
as long as theey do their part to "reopen" their extensions.


> IndexReader.reopen()
> --------------------
>
>                 Key: LUCENE-743
>                 URL: https://issues.apache.org/jira/browse/LUCENE-743
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>            Reporter: Otis Gospodnetic
>            Assignee: Michael Busch
>            Priority: Minor
>         Attachments: IndexReaderUtils.java, lucene-743.patch, MyMultiReader.java, MySegmentReader.java
>
>
> This is Robert Engels' implementation of IndexReader.reopen() functionality, as a set
of 3 new classes (this was easier for him to implement, but should probably be folded into
the core, if this looks good).

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