clohfink commented on a change in pull request #402: New/virtualtables URL: https://github.com/apache/cassandra/pull/402#discussion_r379513446
########## File path: doc/source/new/virtualtables.rst ########## @@ -0,0 +1,586 @@ +.. Licensed to the Apache Software Foundation (ASF) under one +.. or more contributor license agreements. See the NOTICE file +.. distributed with this work for additional information +.. regarding copyright ownership. The ASF licenses this file +.. to you under the Apache License, Version 2.0 (the +.. "License"); you may not use this file except in compliance +.. with the License. You may obtain a copy of the License at +.. +.. http://www.apache.org/licenses/LICENSE-2.0 +.. +.. Unless required by applicable law or agreed to in writing, software +.. distributed under the License is distributed on an "AS IS" BASIS, +.. WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +.. See the License for the specific language governing permissions and +.. limitations under the License. + +Virtual Tables +-------------- + +Apache Cassandra 4.0 implements virtual tables (`CASSANDRA-7622 +<https://issues.apache.org/jira/browse/CASSANDRA-7622>`_). + +Definition +^^^^^^^^^^ + +A virtual table is a table that is backed by an API instead of data explicitly managed and stored as SSTables. Apache Cassandra 4.0 implements a virtual keyspace interface for virtual tables. Virtual tables are specific to each node. + +Objective +^^^^^^^^^ + +A virtual table could have several uses including: + +- Expose JMX data/metrics through CQL +- Expose YAML configuration information +- Expose other MBean data + +How are Virtual Tables different from regular tables? +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Virtual tables and virtual keyspaces are quite different from regular tables and keyspaces respectively such as: + +- Virtual tables are read-only +- Virtual tables are not replicated +- Virtual tables have no associated SSTables +- Consistency level of the queries sent virtual tables are ignored +- Virtual tables are managed by Cassandra and a user cannot run DDL to create new virtual tables or DML to modify existing virtual tables +- Virtual tables are created in special keyspaces and not just any keyspace +- All existing virtual tables use LocalPartitioner Review comment: For LocalPartitioner I am not sure if people will necessarily know what that means so maybe spell out that since its not replicated (which you have above) the partitioner sorts in order of partition keys instead of by their hash. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: pr-unsubscr...@cassandra.apache.org For additional commands, e-mail: pr-h...@cassandra.apache.org
