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From "Uwe Schindler" <>
Subject RE: 2.9 NRT w.r.t. sorting and field cache
Date Tue, 22 Sep 2009 07:59:36 GMT
The NRT reader coming from the IndexWriter.getReader() has only changes in
the currently processed segments, the other segments keep stable (and even
their IndexReader keys used for the FieldCache). The rest of the segments
keep stable. For the consumer it looks like a normal reader (it is in fact a
ReadOnlyDirectoryReader) supporting getSequentialSubReaders() and so on. 


Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen


From: John Wang [] 
Sent: Tuesday, September 22, 2009 9:32 AM
Subject: Re: 2.9 NRT w.r.t. sorting and field cache


Thanks Mark for the pointer!

I guess my point is with NRT, and when segment files change often, this
would be an issue, no?

Anyway, I can run some tests.



On Tue, Sep 22, 2009 at 3:21 PM, Mark Miller <> wrote:

1483 - indexsearcher pulls out a readers subreaders (segmentreaders) and
sends a collector over them one by one, rather than using the multireader.
So only fc for seg readers that change need to be reloaded.  

- Mark (mobile)

On Sep 22, 2009, at 1:27 AM, John Wang <> wrote:

Hi Yonik:

     Actually that is what I am looking for. Can you please point me to
where/how sorting is done per-segment?

     When heaving indexing introduces or modifies segments, would it cause
reloading of FieldCache at query time and thus would impact search



On Tue, Sep 22, 2009 at 1:05 PM, Yonik Seeley <
<>> wrote:

On Tue, Sep 22, 2009 at 12:56 AM, John Wang < <>> wrote:
> Looking at the code, seems there is a disconnect between how/when field
> cache is loaded when IndexWriter.getReader() is called.

I'm not sure what you mean by "disconnect"

> Is FieldCache updated?

FieldCache entries are populated on demand, as they always have been.

> Otherwise, are we reloading FieldCache for each
> reader instance?

Searching/sorting is now per-segment, and so is the use of the
FieldCache.  Segments that don't change shouldn't have to reload their
FieldCache entries.


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