Hi Shawn, Thank you for the explanation.
Regards, Edwin On Wed, 30 Jan 2019 at 15:18, Shawn Heisey <apa...@elyograg.org> wrote: > On 1/28/2019 10:14 AM, Zheng Lin Edwin Yeo wrote: > > We have the following TieredMergePolicyFactory configuration in our > > solrconfig,xml > > > > <mergePolicyFactory > class="org.apache.solr.index.TieredMergePolicyFactory"> > > <int name="maxMergeAtOnce">10</int> > > <int name="maxMergeAtOnceExplicit">10</int> > > <int name="segmentsPerTier">10</int> > > These three settings are the really important ones. Except for > maxMergeAtOnceExplicit, you have these at the default settings. The > default for maxMergeAtOnceExplicit is 30 ... and you shouldn't lower it > without a really good reason. It mostly comes into play during an > optimize ... when you lower it, optimizes may take longer than normal. > It won't be able to merge as many segments at the same time, so the > number of passes required to complete the optimize could increase. > > The most important setting here is segmentsPerTier ... this does not > mean you will never have more than 10 total segments, it means that at > each tier, Lucene will try to keep the number of segments below 10. > With a large index, you are likely to have 3 or 4 tiers, possibly more. > > On an index where I spent a lot of time, my settings were, respective to > yours, 35, 105, and 35. I often had more than 100 segments in those > indexes. It was behaving correctly. > > > What could be the reason that it is not able to merge the segments to 3, > > with each of the segment size to be 5 GB? > > It is working as designed, just not as you expected. > > Thanks, > Shawn >
