Bug #73532 Few shards might generate an uneven distribution
Submitted: 11 Aug 2014 12:24 Modified: 12 Aug 2014 9:17
Reporter: Mats Kindahl Email Updates:
Status: Won't fix Impact on me:
None 
Category:MySQL Fabric Severity:S2 (Serious)
Version:1.4.4 OS:Any
Assigned to: CPU Architecture:Any

[11 Aug 2014 12:24] Mats Kindahl 
Description:
When hash sharding is used, it will assign the nodes to a location on a "hash ring" by computing a hash (MD5) and then compute what shard that a key end up in by computing the hash of the key. This is called consistent hashing.

If a sharded setup is created with very few shards, for example two, then the likelihood of getting a very uneven distribution is large.

How to repeat:
Read the code.

Suggested fix:
Create several virtual nodes on the hash ring for each physical node, for example by computing the MD5 of "<node name>#1", "<node name>#2", ...
[11 Aug 2014 12:26] Mats Kindahl 
This was reported by Jack Tom in http://forums.mysql.com/read.php?144,618275,618275#msg-618275
[6 Jul 2017 19:19] Bugs System 
Status updated to 'Won't fix' (Fabric is now covered under Oracle Lifetime Sustaining Support)