Re: RandomPartitioner and new token allocation algorithm
On Thu, Feb 11, 2016 at 12:28 PM, Sylvain Lebresne wrote: > and honestly the difference with Murmur3 are not big enough that its worth > going through a very painful migration if that's your case > Agreed, after some tests, we didn't found it was an actual issue for our *reasonably sized* clusters. -- Brice
Re: RandomPartitioner and new token allocation algorithm
On Thu, Feb 11, 2016 at 11:56 AM, Romain Hardouin wrote: > I targeted the dev list because I would like to know why the developer > (patch by branimir and reviewed by benedict) mentions "Only supported with > the Murmur3Partitioner" whereas his patch uses IPartitioner interface. (I > will try to reach them on IRC if they don't see this message.) > While the patch uses the IPartitioner interface, it also requires that the Token for the partitioner supported to implement the 2 new methods 'size' and 'increaseSlightly', which only Murmur3Partition tokens does (it throws UnsupportedOperationException for RandomPartitioner in particular). So the documentation in the yaml is correct, only Murmur3Partitioner is currently supported. That said, I think the initial rational for only supporting Murmur3Partitioner is that it's the default and the one recommended, but it's certainly true that old installs are stuck to RandomPartitioner (and honestly the difference with Murmur3 are not big enough that its worth going through a very painful migration if that's your case) and it's not immediately clear to me that adding support for it would be too hard. Feel free to open an improvement ticket for that if you're interested. -- Sylvain
Re: RandomPartitioner and new token allocation algorithm
I targeted the dev list because I would like to know why the developer (patch by branimir and reviewed by benedict) mentions "Only supported with the Murmur3Partitioner" whereas his patch uses IPartitioner interface. (I will try to reach them on IRC if they don't see this message.)
Re: RandomPartitioner and new token allocation algorithm
Yes, at the moment it is not possible to switch from Random to Murmur. We were interested to move to Murmur. And we looked if it was possible when migrating the keyspaces to another datacenter. However this is not possible even while the new datacenter didn’t have the same number of nodes. -- Brice _ From: Russell Hatch Sent: mercredi, février 10, 2016 18:49 Subject: Re: RandomPartitioner and new token allocation algorithm To: Romain Hardouin , (forgot to mention, if there's more to add, please move this over to the standard cassandra mailing list -- this list is used for development of cassandra itself). RandomPartitioner will probably be there for a long time for backwards compat, and if it goes away (unlikely) there would certainly be a migration path. That said, it's still advised to use Murmur unless you really need Random. On Wed, Feb 10, 2016 at 10:21 AM, Romain Hardouin wrote: > > > We have running clusters which use RandomPartitioner that's why I wonder > if we could use this feature in the future. > > Best, > Romain >
Re: RandomPartitioner and new token allocation algorithm
(forgot to mention, if there's more to add, please move this over to the standard cassandra mailing list -- this list is used for development of cassandra itself). RandomPartitioner will probably be there for a long time for backwards compat, and if it goes away (unlikely) there would certainly be a migration path. That said, it's still advised to use Murmur unless you really need Random. On Wed, Feb 10, 2016 at 10:21 AM, Romain Hardouin wrote: > > > We have running clusters which use RandomPartitioner that's why I wonder > if we could use this feature in the future. > > Best, > Romain >
Re: RandomPartitioner and new token allocation algorithm
We have running clusters which use RandomPartitioner that's why I wonder if we could use this feature in the future. Best, Romain
Re: RandomPartitioner and new token allocation algorithm
RandomPartitioner is included for backwards compatibility, though not suggested for new projects. As far as I know Murmur is faster and offers less hotspots in token allocation. Cheers, Russ On Wed, Feb 10, 2016 at 10:04 AM, Romain Hardouin wrote: > Hi all, > > cassandra.yaml mentions that the new token allocation algorithm is only > supported with the Murmur3Partitioner [1]. > When looking at the commit [2] I see that IPartitioner interface is used. > I do see references to Murmur3Partitioner but only in tests classes. > > What would prevent to use RandomPartitioner? > > Thanks, > > Romain > > [1] https://github.com/apache/cassandra/blob/trunk/conf/cassandra.yaml#L35 > [2] > https://github.com/apache/cassandra/commit/9a3fa887cfa03c082f249d1d4003d87c14ba5d24 >
RandomPartitioner and new token allocation algorithm
Hi all, cassandra.yaml mentions that the new token allocation algorithm is only supported with the Murmur3Partitioner [1]. When looking at the commit [2] I see that IPartitioner interface is used. I do see references to Murmur3Partitioner but only in tests classes. What would prevent to use RandomPartitioner? Thanks, Romain [1] https://github.com/apache/cassandra/blob/trunk/conf/cassandra.yaml#L35 [2] https://github.com/apache/cassandra/commit/9a3fa887cfa03c082f249d1d4003d87c14ba5d24
