Map Data Type Disk Incompatibility

Overview

On January 20th, 2015, a user reported issues with Riak data types upon upgrading from Riak 2.0.2 to 2.0.4. It was discovered that keys storing Riak maps are unreadable after upgrading due to a change in the on-disk format of maps that was introduced as a performance improvement.

Identification

You can verify whether this issue is affecting your cluster by checking your cluster’s logs. You will see errors along the following lines if your cluster is affected:

2015-01-21 13:01:00.441 [error]
<0.1033.0>@riak_core_vnode:vnode_command:348 riak_kv_vnode command
failed
{{badrecord,dict},[{dict,filter_dict,2,[{file,"dict.erl"},{line,464}]},{riak_dt_map,'-filter_unique/4-fun-1-',4,[{file,"src/riak_dt_map.erl"},{line,466}]},{sets,fold_bucket,3,[{file,"sets.erl"},{line,313}]},{sets,fold_seg,4,[{file,"sets.erl"},{line,309}]},{sets,fold_segs,4,[{file,"sets.erl"},{line,305}]},{riak_dt_map,merge,2,[{file,"src/riak_dt_map.erl"},{line,454}]},{riak_kv_crdt,'-merge_value/2-fun-0-',5,[{file,"src/riak_kv_crdt.erl"},{line,204}]},{orddict,update,4,[{file,"orddict.erl"},{line,170}]}]}

Affected Users

Users will be affected under the following conditions:

1. They use Riak maps in their cluster
2. They have upgraded to Riak version 2.0.4

If your cluster does not use Riak maps you may upgrade to 2.0.4 as normal.

Mitigation Strategy

The recommended mitigation strategy is to upgrade to Riak 2.0.5 or later.