Correction: mergeFactor determines how many segments are merged at once. It's IndexWriter's ramBufferSizeMB and/or maxBufferedDocs that determine how many docs are buffered in RAM before a new segment is flushed.
A higher mergeFactor will require more RAM during merging, will cause longer running but fewer merges, requires more open files, and allows your index to have more segments given a certain number of indexed docs. Mike On Tue, Aug 10, 2010 at 4:24 AM, anshum.gu...@naukri.com <ansh...@gmail.com> wrote: > Would like to know, are you using a particular type of sort? Do you need to > sort on relevance? Can you shard and restrict your search to a limited set of > indexes functionally? > > -- > Anshum > http://blog.anshumgupta.net > > Sent from BlackBerry® > > -----Original Message----- > From: Shelly_Singh <shelly_si...@infosys.com> > Date: Tue, 10 Aug 2010 13:31:38 > To: java-user@lucene.apache.org<java-user@lucene.apache.org> > Reply-To: java-user@lucene.apache.org > Subject: RE: Scaling Lucene to 1bln docs > > Hi Anshum, > > I am already running with the 'setCompoundFile' option off. > And thanks for pointing out mergeFactor. I had tried a higher mergeFactor > couple of days ago, but got an OOM, so I discarded it. Later I figured that > OOM was because maxMergeDocs was unlimited and I was using MMap. U r rigt, I > should try a higher mergeFactor. > > With regards to the multithreaded approach, I was considering creating 10 > different threads each indexing 100mln docs coupled with a Multisearcher to > which I will feed these 10 indices. Do you think this will improve > performance. > > And just FYI, I have latest reading for 1 bln docs. Indexing time is 2 hrs > and search time is 15 secs.. I can live with indexing time but the search > time is highly unacceptable. > > Help again. > > -----Original Message----- > From: Anshum [mailto:ansh...@gmail.com] > Sent: Tuesday, August 10, 2010 12:55 PM > To: java-user@lucene.apache.org > Subject: Re: Scaling Lucene to 1bln docs > > 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 > intermittently. > 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 > threads. > > -- > Anshum Gupta > http://ai-cafe.blogspot.com > > > On Tue, Aug 10, 2010 at 12:24 PM, Shelly_Singh > <shelly_si...@infosys.com>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: shelly_si...@infosys.com<mailto:shelly_si...@infosys.com> >> Phone: (M) 91 992 369 7200, (VoIP)2022978622 >> >> >> >> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
