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mck edited comment on CASSANDRA-15260 at 8/7/19 4:54 PM: --------------------------------------------------------- {quote} Meanwhile, for consistency's sake I would change the name of the option to match DSE's as it is doing exactly the same thing. {quote} No objection. I will fix it. The naming is a bit clumsy either way imho, but nothing better comes to mind, and indeed it makes sense to re-use DSE's terminology for an identical feature. {quote}We may be doing more damage than good over e.g. 256-vnode random choice, …{quote} Makes sense and is fine by me. It helps to just have these concerns, and the trade-off, stated somewhere. was (Author: michaelsembwever): {quote} Meanwhile, for consistency's sake I would change the name of the option to match DSE's as it is doing exactly the same thing. \{quote} No objection. I will fix it. The naming is a bit clumsy either way imho, but nothing better comes to mind, and indeed it makes sense to re-use DSE's terminology for an identical feature. {quote}We may be doing more damage than good over e.g. 256-vnode random choice, …\{quote} Makes sense and is fine by me. It helps to just have these concerns, and the trade-off, stated somewhere. > Add `allocate_tokens_for_dc_rf` yaml option for token allocation > ---------------------------------------------------------------- > > Key: CASSANDRA-15260 > URL: https://issues.apache.org/jira/browse/CASSANDRA-15260 > Project: Cassandra > Issue Type: Improvement > Components: Local/Config > Reporter: mck > Assignee: mck > Priority: Normal > Fix For: 4.x > > > Similar to DSE's option: {{allocate_tokens_for_local_replication_factor}} > Currently the > [ReplicationAwareTokenAllocator|https://www.datastax.com/dev/blog/token-allocation-algorithm] > requires a defined keyspace and a replica factor specified in the current > datacenter. > This is problematic in a number of ways. The real keyspace can not be used > when adding new datacenters as, in practice, all its nodes need to be up and > running before it has the capacity to replicate data into it. New datacenters > (or lift-and-shifting a cluster via datacenter migration) therefore has to be > done using a dummy keyspace that duplicates the replication strategy+factor > of the real keyspace. This gets even more difficult come version 4.0, as the > replica factor can not even be defined in new datacenters before those > datacenters are up and running. > These issues are removed by avoiding the keyspace definition and lookup, and > presuming the replica strategy is by datacenter, ie NTS. This can be done > with the use of an {{allocate_tokens_for_dc_rf}} option. > It may also be of value considering whether {{allocate_tokens_for_dc_rf=3}} > becomes the default? as this is the replication factor for the vast majority > of datacenters in production. I suspect this would be a good improvement over > the existing randomly generated tokens algorithm. > Initial patch is available in > [https://github.com/thelastpickle/cassandra/commit/fc4865b0399570e58f11215565ba17dc4a53da97] > The patch does not remove the existing {{allocate_tokens_for_keyspace}} > option, as that provides the codebase for handling different replication > strategies. > > fyi [~blambov] [~jay.zhuang] [~chovatia.jayd...@gmail.com] [~alokamvenki] > [~alexchueshev] -- This message was sent by Atlassian JIRA (v7.6.14#76016) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org