On 9/16/2013 7:01 AM, Matteo Grolla wrote: > Can anyone explain me the following things about soft-commit? > -For searches o access new documents I think a new searcher is opened after a > soft commit. > How does the near realtime requirement for soft commit match with the > potentially long time taken to warm up caches for the new searcher? > -Is it a good idea to set > openSearcher=false in auto commit > and rely on soft auto commit to see new data in searches?
That is a very common way for installs requiring NRT updates to get configured. NRTCachingDirectoryFactory, which is the directory class used in the example since 4.0, is a wrapper around MMapDirectoryFactory, which is the old default in 3.x. For soft commits, the NRT directory keeps small commits in RAM rather than writing it to the disk, which makes the process of opening a new searcher happen a lot faster. http://lucene.apache.org/core/4_4_0/core/org/apache/lucene/store/NRTCachingDirectory.html If your index rate is very fast or you index large amounts of data, the NRT directory doesn't gain you much over MMap, but because we made it the default in the example, it probably doesn't have any performance detriment. Thanks, Shawn
