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From Stanislav Jordanov <ste...@sirma.bg>
Subject Re: The best way to know when an index has been changed
Date Wed, 03 Aug 2005 14:39:25 GMT
Hi Steve,

we have a similar situation and we choosed the following solution:
The process that modifies the index (the writer) notifies the process 
that searches the index (the reader)
In our case the notification is a specificly named subdirectory 
"index_modified" of the directory containing the index files.
After each update to the index (or if it turns out to slow down the 
indexing process - make it not not more than once a minute)
the writer process raises the flag by creating the directory if it does 
not exists.
On the other hand the reader removes the directory each time it 
recreates its Searcher.
Does this approach suit your needs?

Regards:
Stanislav

Steve Gaunt wrote:

>Hi Luke
>
>It's a good idea, but we need to know instantly the fail over happens.
>We obtain a new instance of the index searcher every night anyway to
>obtain the latest index.  When the fail over happens, the index location
>is in the same place, but was wandering if there was a way to find out
>if the index has changed without the database hit the first search hits
>lucene after the failover.
>
>Hope this explains the scenario more clearly.
>
>Steve
>
>
>
>-----Original Message-----
>From: Luke [mailto:luke@lukeshannon.com] 
>Sent: 03 August 2005 14:47
>To: java-user@lucene.apache.org
>Subject: Re: The best way to know when an index has been changed
>
>Hi Steve;
>
>Not sure if this would work...
>
>Each day you could get the value from IndexReader's  getCurrentVersion
>and
>store it somewhere (DB or serialize it). The next day when you grab the
>value again you could compare it to the stored one, if they differ you
>would
>know it has been replaced.
>
>Luke
>
>----- Original Message ----- 
>From: "Steve Gaunt" <SGaunt@emeraldinsight.com>
>To: <java-user@lucene.apache.org>
>Sent: Wednesday, August 03, 2005 9:34 AM
>Subject: The best way to know when an index has been changed
>
>
>  
>
>>Hi
>>
>>We have a web app, which keep a copy of the index searcher, then
>>    
>>
>reloads
>  
>
>>the index searcher every night to obtain the latest version of the
>>index( as it updates every day).
>>However, we have a fail over mode, which will eventually use another
>>index on another server, it there anyway to know if the underlying
>>    
>>
>index
>  
>
>>has been replaced with another index???
>>
>>
>>Cheers in advance
>>
>>Steve
>>
>>
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>>    
>>
>
>
>
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