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From Otis Gospodnetic <otis_gospodne...@yahoo.com>
Subject RE: Concurrency
Date Sat, 28 Feb 2004 18:22:07 GMT
I'm not sure what happens on Windows, but this should work just fine
under UNIX.  The files still really do exist on disk, I believe, they
are just not visible after you delete them, and under UNIX the process
will still have a references to deleted index files (inodes is the
proper term in this context, I think) even after optimization, so
IndexSearcher will work.
This is easy to test.

Otis


--- David Townsend <david.townsend@magus.co.uk> wrote:
> Does this mean that if an IndexSearcher has hold of a segment file,
> then the index is optimised, any subsequent search will use a list of
> files that probably don't exist anymore?
> 
> David Townsend
> 
> -----Original Message-----
> From: Otis Gospodnetic [mailto:otis_gospodnetic@yahoo.com]
> Sent: 20 February 2004 13:26
> To: Lucene Users List
> Subject: Re: Concurrency
> 
> 
> > Ive just got a couple of questions which i cant quite work
> > out...wondered if 
> > someone could help me with them:
> > 
> > 1. What happens if i make a backup (copy) of an index while
> documents
> > are 
> > being added? Can it cause problems, and if so is there a way to
> > safely do 
> > this?
> 
> You should be okay.  When new documents are added, they are added to
> new segments.  A 'table of contents' of all valid segments is in
> 'segments' file.  Even if you copy extra segments, your index will
> still work, it's just that your searches may not search newly created
> segments, whose existence was not registered in segments file, when
> you
> copied the index.
> 
> > 2. When I create a new IndexSearcher, what method does Lucene use
> to
> > take a 
> > 'snapshot' of the index (because if i add documents after the
> search
> > object 
> > is created they dont appear in the search results)?
> 
> This is related to the answer under 1.  New documents are not seen
> with
> an old IndexSearcher, because the old IndexSearcher is not aware of
> new
> segments.
> It would have to re-read the segments file and read any new segments
> found, in order to become aware of new segments and documents in
> them.
> 
> Otis
> 
> 
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