From user-return-64354-archive-asf-public=cust-asf.ponee.io@cassandra.apache.org Sat Aug 17 17:53:36 2019 Return-Path: X-Original-To: archive-asf-public@cust-asf.ponee.io Delivered-To: archive-asf-public@cust-asf.ponee.io Received: from mail.apache.org (hermes.apache.org [207.244.88.153]) by mx-eu-01.ponee.io (Postfix) with SMTP id 3CB80180181 for ; Sat, 17 Aug 2019 19:53:36 +0200 (CEST) Received: (qmail 94277 invoked by uid 500); 17 Aug 2019 17:53:34 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 94266 invoked by uid 99); 17 Aug 2019 17:53:34 -0000 Received: from ui-eu-02.ponee.io (HELO localhost) (116.202.110.96) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 17 Aug 2019 17:53:34 +0000 x-ponymail-agent: PonyMail Composer/0.2 MIME-Version: 1.0 Subject: Consistent hashing vnodes and ring in cassandra x-ponymail-sender: 888e35de21e955c9f73fe4e5cbf8d8f9bf6a2ab7 From: Inquistive allen Message-ID: Content-Type: text/plain; charset=utf-8 Date: Sat, 17 Aug 2019 17:53:32 -0000 To: References: X-Mailer: LuaSocket 3.0-rc1 In-Reply-To: I am a newbie in cassandra. I have asked this question on various platforms but never got a satisfying answer. Hence thought of bringing up the topic here. Sorry for this might be a simple question. 1. I studied the paper on consistent hashing (which is being implemented in Cassandra) 2. Cassandra has the concept of Vnodes. The vnodes( As I understand a Vnode is a collection of Hashes) , are the basic blocks of replication in cassandra. It is the vnodes which are replicated across the cluster. Please do correct me I'm wrong 3. Suppose I have a Keyspace A with replication factor 3 and Keyspace B with replication factor 2. 4. Is it that a Vnode is a collection of hashes of data from various Keyspaces. 5. In that case, Keyspace with varying replication factors , replicating them to other nodes would be a problem 6. Now from the consistent hashing paper, I get a feeling that , ach Keyspace has a different ring. Also the name "KEYSPACE", points to a ring of keys in the ring. So is it that each keyspace has a different ring. If it is so, everything else like replicating vnodes among nodes in the cluster would fall in place. Each Keyspace has a different ring ---> each Vnode has data of various tables from a given keyspace----> hence copies equal to RF is only made in the cluster. I know I am missing something. This way of understanding thing might be wrong. Kindly help me understand the same. As this would help me visualise repair, bootstrap, adding cluster, streaming operations in a much better way. --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscribe@cassandra.apache.org For additional commands, e-mail: user-help@cassandra.apache.org