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From Lance Norskog <goks...@gmail.com>
Subject Re: Taking backup of a Lucene index
Date Thu, 06 Jun 2013 05:38:18 GMT
The simple answer (that somehow nobody gave) is that you can make a copy 
of an index directory at any time. Indexes are changed in "generations". 
The segment* files describe the current generation of files. All active 
indexing goes on in new files. In a commit, all new files are flushed to 
disk and then the segment* files change. At any point in this sequence, 
all of the files in the directory form one consistent index.

This isn't like MySQL or other databases where you have to shut down the 
DB to get a safe copy of the files.

Lance

On 04/17/2013 03:57 AM, Ashish Sarna wrote:
> I want to take back-up of a Lucene index. I need to ensure that index files
> would not change when I take their backup.
>
>   
>
> I am concerned about the housekeeping/merge/optimization activities which
> Lucene performs internally. I am not sure when/how these activities are
> performed by Lucene and how we can prevent them.
>
>   
>
> My application (which allows indexing and searching over the created
> indexes) keeps running in the background. I can ensure that nothing is
> written to the indexes by my application when I take their backup, but I am
> not sure whether indexes would change in some manner when a search is
> performed over it.
>
>   
>
> How can I ensure that an index would not change (i.e., no
> housekeeping/merge/optimization activity is performed by Lucene) when I take
> its backup?
>
>   
>
> Any help would be much appreciated.
>
>   
>
> PS: Currently I am using Lucene 2.9.4 but wish to upgrade it to 3.6.2.
>
>   
>
> Regards
>
> Ashish
>
>


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