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From Marcel Reutegger <marcel.reuteg...@gmx.net>
Subject Re: Is doc addition / indexing synchronous or asynchronous?
Date Mon, 10 Apr 2006 13:29:04 GMT
thomasg wrote:
> Yes I ran another query straight after and the execution time drops from
> 37000ms to 16ms! So the delay when the query is first ran is due to text
> extraction and indexing having to complete? 
> This leads to another question. Page 59 of Lucene In Action states:
> "Any number of read-only operations may be executed while an index is being
> modified. For example, users can search an index while it's being optimized
> or while new documents are being added to the index, updated, or deleted
> from the index."
> It seems that this behaviour of Lucene is not the situation when Jackrabbit
> integrates with Lucene. Is there a reason for the index not being readable
> while the extraction / indexing takes place?

what you see in your example when you add a large document is also about 
consistency. jackrabbit guarantees that once you add a node it is 
immediately searchable. even though there is some buffering going on 
behind the scenes. executing a query earlier on an incomplete index 
could lead to wrong results.

in general jackrabbit allows you to make changes to the index while 
queries are running. the other way round is not always true. if there is 
an open reader on the index while changes are made to the index then you 
can also execute a query on it. but it may happen that no reader is open 
at all, then the 'reading' thread on the index is blocked until the 
writing is completed.

you can try this out by executing queries in jackrabbit with one session 
and then add the large document with another session. the first thread 
should keep executing the queries even though the document is added. at 
least that's the intended behaviour ;)


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