You may be confusing the number of shards you configure and how they expand using the SPLITSHARD command. That command creates two shards where there was one before, so in that sense Solr collections can grow by a factor of 2. But that doesn't mean anything about the number of shards you started with. I.e. I can start with 3 shards, then use SPLITSHARD and have 6, use SPLITSHARD again and have 12 etc....
Best, Erick On Tue, Apr 4, 2017 at 9:22 PM, Walter Underwood <wun...@wunderwood.org> wrote: >> On Apr 4, 2017, at 7:38 PM, Muhammad Imad Qureshi >> <imadgr...@yahoo.com.INVALID> wrote: >> >> Hi >> I was recently told that ideally the number of shards in a SOLR cluster >> should be equal to a power of 2. If this is indeed a best practice, then >> what is the rationale behind this recommendation? ThanksImad > > I don’t know of any such recommendation. Assuming you are not RAM or disk > limited, going to two or three shards won’t help a lot. If those get you out > of a bottleneck, you’ll see a difference. > > I believe that some of the performance of Solr is proportional to the number > of distinct terms in the index (the vocabulary). A rule of thumb is the > vocabulary is proportional to the square root of the number of terms in the > index. Which is often related to the number of documents. With this > assumption, four shards gives a 2X speedup. Which has worked for me. > > wunder > Walter Underwood > wun...@wunderwood.org > http://observer.wunderwood.org/ (my blog) >
