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From Anshum <>
Subject Re: Scaling Lucene to 1bln docs
Date Tue, 10 Aug 2010 07:25:03 GMT
Hi Shelly,
That seems like a reasonable data set size. I'd suggest you increase your
mergeFactor as a mergeFactor of 10 says, you are only buffering 10 docs in
memory before writing it to a file (and incurring I/O). You could actually
flush by RAM usage instead of a Doc count. Turn off using the Compound file
structure for indexing as it generally takes more time creating a cfs index.

Plus the time would not grow linearly as the larger the size of segments
get, the more time it'd take to add more docs and merge those together
You may also use a multithreaded approach in case reading the source takes
time in your case, though, the indexwriter would have to be shared among all

Anshum Gupta

On Tue, Aug 10, 2010 at 12:24 PM, Shelly_Singh <>wrote:

> Hi,
> I am developing an application which uses Lucene for indexing and searching
> 1 bln documents. (the document size is very small though. Each document has
> a single field of 5-10 words; so I believe that my data size is within the
> tested limits).
> I am using the following configuration:
> 1.      1.5 gig RAM to the jvm
> 2.      100GB disk space.
> 3.      Index creation tuning factors:
> a.      mergeFactor = 10
> b.      maxFieldLength = 10
> c.      maxMergeDocs = 5000000 (if I try with a larger value, I get an
> out-of-memory)
> With these settings, I am able to create an index of 100 million docs (10
> pow 8)  in 15 mins consuming a disk space of 2.5gb. Which is quite
> satisfactory for me, but nevertheless, I want to know what else can be done
> to tune it further. Please help.
> Also, with these settings, can I expect the time and size to grow linearly
> for 1bln (10 pow 9) documents?
> Thanks and Regards,
> Shelly Singh
> Center For KNowledge Driven Information Systems, Infosys
> Email:<>
> Phone: (M) 91 992 369 7200, (VoIP)2022978622

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