Bug in calculating QUORUM
-------------------------
Key: CASSANDRA-1487
URL: https://issues.apache.org/jira/browse/CASSANDRA-1487
Project: Cassandra
Issue Type: Bug
Components: Core
Affects Versions: 0.7 beta 1
Reporter: Jignesh Dhruv
Hello,
It seems that there is a bug in calculating QUORUM in
src/java/org/apache/cassandra/service/QuorumResponseHandler.java
Currently the QUORUM formula in place will return correct QUORUM if replication
factor <= 3. However if you have a Replication Factor > 3, it will return
incorrect result.
-----------------------
--- src/java/org/apache/cassandra/service/QuorumResponseHandler.java
(revision 995482)
+++ src/java/org/apache/cassandra/service/QuorumResponseHandler.java
(working copy)
@@ -109,7 +109,7 @@
case ANY:
return 1;
case QUORUM:
- return (DatabaseDescriptor.getQuorum(table)/ 2) + 1;
+ return DatabaseDescriptor.getQuorum(table);
case ALL:
return DatabaseDescriptor.getReplicationFactor(table);
default:
-------------------
In QuorumResponseHandler:determineBlockFor()
DatabaseDescriptor.getQuorum(table) is already returning a quorum value which
is further divided by 2 and a one is added.
So say if your RF=6, it is suppose to check 4 replicas, (6/2)+1-4 but it ends
up checking only 3 replicas as DatabaseDescriptor.getQuorum returns 4, so
determineBlockFor will return (4/2)+1=3.
Let me know if you have any questions.
Jignesh
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