Thanks Kumaran and Erik for resolving my queries. Kumaran, You are right at only one indexwriter can write as it acquire the lock but using the NRT manager APis - TrackingIndexWriter <http://lucene.apache.org/core/4_4_0/core/org/apache/lucene/index/TrackingIndexWriter.html> multiple concurrent updates/delete/append is possible.
Thanks again ! On Mon, Aug 4, 2014 at 10:29 PM, Erick Erickson <erickerick...@gmail.com> wrote: > Right. > 1> Occasionally the merge will require 2x the disk space. (3x in compound > file system). The merging is, indeed, done in the background, it is NOT a > blocking operation. > > 2> n/a. It shouldn't block at all. > > Here's a cool video by Mike McCandless on the merging process, plus some > explanations: > > > http://blog.mikemccandless.com/2011/02/visualizing-lucenes-segment-merges.html > > Best, > Erick > > > > > On Mon, Aug 4, 2014 at 8:45 AM, Kumaran R <kums....@gmail.com> wrote: > > > Hi Gaurav > > > > 1.When you opened index to write,till you close that index, there will > > be a lock to do further write. But not for search. During merge, index > > needs 3X ( not sure 2X?) of more storage space, i believe that is the > > reason for no blocking for search. ( any other experts can clarify you > > more on this ) > > > > 2. Merge will be taken care by default values( merge factor 2) of > > lucene. If u need to control more on merge policy, please go through > > about merge by size or by number of segments or many merge policies. > > > > > > Hope this will help you a little bit. > > > > -- > > Kumaran R > > Sent from Phone > > > > > On 04-Aug-2014, at 8:04 pm, Gaurav gupta <gupta.gaurav0...@gmail.com> > > wrote: > > > > > > Hi, > > > > > > We are planning to use Lucene 4.8.1 over Oracle (1 to 2 TB data) and > > > seeking information on "How Lucene conduct housekeeping or maintenance > > of > > > indexes over a period of time". *Is it a blocking operation for write > and > > > search or it will not block anything while merging is going on? * > > > > > > I found :- *"Since Lucene adds the updated document to the index and > > marks > > > all previous versions as deleted. So to get rid of deleted documents > > Lucene > > > needs to do some housekeeping over a period of time. Under the hood is > > that > > > from time to time segments are merged into (usually) bigger segments > > > using configurable MergePolicy > > > < > > > http://lucene.apache.org/java/3_4_0/api/core/org/apache/lucene/index/MergePolicy > > > > > > (TieredMergePolicy). > > > "* > > > > > > 1- Is it's a blocking operation for write and search both or it will > not > > > block anything while merging is going on? > > > > > > 2- What is the best practice to avoid any blocking in production > servers? > > > Not sure how Solr or Elasticsearch is handling it. > > > Should we control the merging by calling *forcemerge(int) at low > traffic > > > time *to avoid any unpredictable blocking operation? Is it recommended > or > > > Lucene do intelligent merging and don't block anything (updates and > > > searches) or there are ways to reduce the blocking time to a very small > > > duration (1 -2 minutes) using some API or demon thread etc. > > > > > > Looking for your professional guidance on it. > > > > > > Regards > > > Gaurav > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > > For additional commands, e-mail: java-user-h...@lucene.apache.org > > > > >
