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From Michael McCandless <luc...@mikemccandless.com>
Subject Re: Searching Problem
Date Thu, 26 Oct 2006 13:21:34 GMT
Sunil Kumar PK wrote:
> could you please explain?
> 
> On 10/26/06, Karel Tejnora <karel@tejnora.cz> wrote:
>> Nope. IndexReader obtains a snapshot of index - not closing and opening
>> indexreader leads to not deleting files (windows exception, linux will
>> not free them).
>> > Is it possible to get all the matching document in the result without
>> > restarting the Searcher program?

A searcher once created only searches the index as of the "point in 
time" that it was created.  Ie, it's an unchanging snapshot.  So any 
deletes/updates that happen to the index by a writer will not be visible 
until you close and reopen another searcher.

This "point in time" searching relies on certain properties of the 
underlying filesystem in order to work properly.  Windows local and 
remote (SMB) filesystems work because files that are open can't be 
deleted (and Lucene just retries); local UNIX filesystems work because 
the open file handle can still access a deleted file ("delete on last 
close").

However: NFS does not have "delete on last close", so you can't rely on 
"point in time" searching when using NFS across machines (it's possible 
a single machine may work).  If a writer on a different machine has 
committed to the index that a searcher is using over NFS then the 
searcher will eventually hit an IOException with "stale NFS handle". 
See here for details on current known issues with NFS:

   http://issues.apache.org/jira/browse/LUCENE-673

Mike

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