Advanced sharding with SolrCloud
Let's explore some of the advanced concepts of sharding, starting with shard splitting.
Let us say that we have created a two-shard replica looking at the current number of queries per second for a system. In future, if the number of queries per second increases to, say, twice or thrice the current value, we will need to add more shards. Now, one way is to create a separate cloud with say four shards and re-index all the documents. This is possible if the cluster is small. If we are dealing with a 50 shard cluster with more than a billion documents, re-indexing of the complete set of documents again may be expensive. For such scenarios, SolrCloud has the concept of shard splitting.
In shard splitting, ...