OPP#describeOwnership reports incorrect ownership
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Key: CASSANDRA-2800
URL: https://issues.apache.org/jira/browse/CASSANDRA-2800
Project: Cassandra
Issue Type: Bug
Affects Versions: 0.7.4
Reporter: Jon Hermes
Assignee: Jon Hermes
Priority: Minor
Fix For: 0.7.7, 0.8.2
Attachments: 2800.txt
OPP#describeOwnership relies on StorageService#getSplits and counts the
received tokens as its basis of ownership.
When the number of result keys is less than the number of splits, the full
count is omitted (to save work?). However, we don't care if a split would end
up fractional in this case, we just need the full count.
The logic here is:
{code}
int splits = keycount * DatabaseDescriptor.getIndexInterval() / keysPerSplit;
if (keycount >= splits) { ... add count to result set }
{code}
We were passing in 1 key per split (since we just care about the count), but
splits=keycount*IndexInterval is guaranteed to be > keycount, so the result set
is not completely formed.
The better "unit keysPerSplit" to use is IndexInterval itself, which gives
splits=keycount*II/II=keycount, so the logic runs correctly.
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