The only time that a force merge might be useful is when you reindex all content every night or every week, then do not make any changes until the next reindex. But even then, it probably does not matter.
Just let Solr do its thing. Solr is pretty smart. A long time ago (1996-2006), I worked on an enterprise search engine with the same merging algorithm as Solr (Ultraseek Server). We always had customers asking about force-merge/optimize. It never made a useful difference. Even with twenty servers at irs.gov <http://irs.gov/>, it didn’t make a difference. wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) > On Dec 29, 2015, at 6:59 PM, Zheng Lin Edwin Yeo <edwinye...@gmail.com> wrote: > > Hi Walter, > > Thanks for your reply. > > Then how about optimization after indexing? > Normally the index size is much larger after indexing, then after > optimization, the index size reduces. Do we still need to do that? > > Regards, > Edwin > > On 30 December 2015 at 10:45, Walter Underwood <wun...@wunderwood.org> > wrote: > >> Do not “optimize". >> >> It is a forced merge, not an optimization. It was a mistake to ever name >> it “optimize”. Solr automatically merges as needed. There are a few >> situations where a force merge might make a small difference. Maybe 10% or >> 20%, no one had bothered to measure it. >> >> If your index is continually updated, clicking that is a complete waste of >> resources. Don’t do it. >> >> wunder >> Walter Underwood >> wun...@wunderwood.org >> http://observer.wunderwood.org/ (my blog) >> >>> On Dec 29, 2015, at 6:35 PM, Zheng Lin Edwin Yeo <edwinye...@gmail.com> >> wrote: >>> >>> Hi, >>> >>> I am facing a situation, when I do an optimization by clicking on the >>> "Optimized" button on the Solr Admin Overview UI, the memory usage of the >>> server increases gradually, until it reaches near the maximum memory >>> available. There is 64GB of memory available in the server. >>> >>> Even after the optimized is completed, the memory usage stays near the >> 100% >>> range, and could not be reduced until I stop Solr. Why could this be >>> happening? >>> >>> Also, I don't think the optimization is completed, as the admin page says >>> the index is not optimized again after I go back to the Overview page, >> even >>> though I did not do any updates to the index. >>> >>> I am using Solr 5.3.0, with 1 shard and 2 replica. My index size is >> 183GB. >>> >>> Regards, >>> Edwin >> >>
