Way too high would cause it to pick highly lopsided merges just because a few deletes were removed.
Highly lopsided merges (e.g. one big segment and N tiny segments) can be horrible because it can lead to O(N^2) merge cost over time. Mike McCandless http://blog.mikemccandless.com On Wed, Jun 19, 2013 at 1:36 PM, Petersen, Robert <robert.peter...@mail.rakuten.com> wrote: > OK thanks, will do. Just out of curiosity, what would having that set way > too high do? Would the index become fragmented or what? > > -----Original Message----- > From: Michael McCandless [mailto:luc...@mikemccandless.com] > Sent: Wednesday, June 19, 2013 9:33 AM > To: solr-user@lucene.apache.org > Subject: Re: TieredMergePolicy reclaimDeletesWeight > > The default is 2.0, and higher values will more strongly favor merging > segments with deletes. > > I think 20.0 is likely way too high ... maybe try 3-5? > > > Mike McCandless > > http://blog.mikemccandless.com > > > On Tue, Jun 18, 2013 at 6:46 PM, Petersen, Robert > <robert.peter...@mail.rakuten.com> wrote: >> Hi >> >> In continuing a previous conversation, I am attempting to not have to >> do optimizes on our continuously updated index in solr3.6.1 and I came >> across the mention of the reclaimDeletesWeight setting in this blog: >> http://blog.mikemccandless.com/2011/02/visualizing-lucenes-segment-mer >> ges.html >> >> We do a *lot* of deletes in our index so I want to make the merges be more >> aggressive on reclaiming deletes, but I am having trouble finding much out >> about this setting. Does anyone have experience with this setting? Would >> the below accomplish what I want ie for it to go after deletes more >> aggressively than normal? I got the impression 10.0 was the default from >> looking at this code but I could be wrong: >> https://builds.apache.org/job/Lucene-Solr-Clover-trunk/lastSuccessfulB >> uild/clover-report/org/apache/lucene/index/TieredMergePolicy.html?id=3 >> 085 >> >> <mergePolicy class="org.apache.lucene.index.TieredMergePolicy"> >> <int name="maxMergeAtOnce">20</int> >> <int name="segmentsPerTier">8</int> >> <double name="reclaimDeletesWeight">20.0</double> >> </mergePolicy> >> >> Thanks >> >> Robert (Robi) Petersen >> Senior Software Engineer >> Search Department >> > >
