It If you only have 100 partitions, then having more than (100 * RF) nodes doesn’t help you much.
However, unless you’re using very specific partitioners, there’s no guarantee that you’ll have 1 partition per node (with 10 nodes / 10 partitions). Cassandra uses murmur3 hash (by default, and md5 in old versions) to hash the partition key to place data onto a node. You have very little control over distribution – murmur3 and md5 are both sufficiently distributed that you’re likely to have a good distribution on sufficiently high number of partitions, but with 100 partitions, you’re going to have a miserable time. If your data model is such that you’re only ever going to have 100 partitions, your data model is broken, or you should use some other database. From: S Ahmed <sahmed1...@gmail.com> Reply-To: "firstname.lastname@example.org" <email@example.com> Date: Wednesday, September 21, 2016 at 2:40 PM To: "firstname.lastname@example.org" <email@example.com> Subject: understanding partitions and # of nodes Hello, If you have a 10 node cluster, how does having 10 partitions or 100 partitions change how cassandra will perform? With 10 partitions you will have 1 partition per node. WIth 100 partitions you will have 10 partitions per node. With 100 partitions I guess it helps because when you add more nodes to your cluster, the data can be redistributed since you have more nodes. What else are things to consider? Thanks.
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