Thanks Shawn, Can you please re-direct me to any wiki which describes (in detail) the differences between MMapDirectoryFactory and NRTCachingDirectoryFactory? I found this blog <http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on-64bit.html> very helpful which describes about MMapDirectory. I want to know in detail about NRTCachingFactory as well.
Also, when I ran this rest request solr/admin/cores?action=STATUS, I got the below result (pasted partial result only). I have set the DirectoryFactory as NRTCachingDirectory in solrconfig.xml. But, it also shows MMapDirectory in the below element. Does this means NRTCachingDirectory is using MMapDirectory internally?? <str name="directory"> org.apache.lucene.store.NRTCachingDirectory:NRTCachingDirectory(MMapDirectory@/instance/solr/collection1_shard2_replica1/data/index lockFactory=NativeFSLockFactory@/instance/solr/collection1_shard2_replica1/data/index; maxCacheMB=48.0 maxMergeSizeMB=4.0)</str> What does maxCacheMB and maxMergeSizeMB indicate? How to control it? Thanks, Manohar On Fri, Dec 5, 2014 at 11:04 AM, Shawn Heisey <apa...@elyograg.org> wrote: > On 12/4/2014 10:06 PM, Manohar Sripada wrote: > > If you use MMapDirectory, Lucene will map the files into memory off heap > > and the OS's disk cache will cache the files in memory for you. Don't use > > RAMDirectory, it's not better than MMapDirectory for any use I'm aware > of. > > > >> Will that mean it will cache the Inverted index as well to OS disk's > > cache? The reason I am asking is, Solr searches this Inverted Index first > > to get the data. How about if we can keep this in memory? > > If you have enough memory, the operating system will cache *everything*. > It does so by simply loading the data that's on the disk into RAM ... > it is not aware that certain parts are the inverted index, it simply > caches whatever data gets read. A subsequent read will come out of > memory, the disk heads will never even move. If certain data in the > index is never accessed, then it will not get cached. > > http://en.wikipedia.org/wiki/Page_cache > > Thanks, > Shawn > >
