Re: [bailey-developers] lattice master

[Yonik S. <yo...@ap...>]

On Wed, Feb 27, 2008 at 3:58 PM, Ning Li <nin...@gm...> wrote:
> On Tue, Feb 26, 2008 at 1:21 PM, Yonik Seeley <yo...@ap...> wrote:
>  > I think one problem we are running into is due to using the same hash
>  >  ring for both partitioning the key space and selecting placement of
>  >  those keys.  Putting many virtual nodes on the hash ring to make the
>  >  hash function fair, in conjunction with using that hash ring to do
>  >  replication, causes all the indicies to be mixed together.
>
>  What we have discussed addressed partitioning and replication:
>  1 We used consistent hashing to partition keys into ranges.
>    We may call a range "shard". The important thing is, it is
>    a one-to-one mapping between ranges and virtual nodes.
>  2 We described one replication scheme on how a virtual node
>    replicates its range/shard on N-1 virtual nodes with replication
>    level set to N.

As I read the previous messages, it seems like both #1 and #2 are
using the same hash circle.
It seems like using virtual nodes (as opposed to real nodes) to
determine replication means that you can't query every N real nodes
and cover the entire index, right?   It seems like the replica for
real node A is distributed over all other nodes, regardless of what N
is.

-Yonik