write endpoints are not treated correctly, breaking consistency guarantees
--------------------------------------------------------------------------
Key: CASSANDRA-3901
URL: https://issues.apache.org/jira/browse/CASSANDRA-3901
Project: Cassandra
Issue Type: Sub-task
Components: Core
Reporter: Peter Schuller
Assignee: Peter Schuller
Priority: Critical
I had a nagging feeling this was the case ever since I started wanting
CASSANDRA-3833 and thinking about hot to handle the association between nodes
in the read set and nodes in the write set.
I may be wrong (please point me in the direct direction if so), but I see no
code anywhere that tries to (1) apply consistency level to currently normal
endpoints only, and (2) "connect" a given read endpoint with a future write
endpoint such that they are tied together for consistency purposes (parts of
these concerns probably is covered by CASSANDRA-2434 but that ticket is more
general).
To be more clear about the problem: Suppose we have a ring of nodes, with a
single node bootstrapping. Now, for a given row key suppose reads are served by
A, B and C while writes are to go to A, B, C and D. In other words, D is the
node bootstrapping. Suppose RF is 3 and A,B,C,D is ring order. There are a few
things required for correct behavior:
* Writes acked by D must never be treated as sufficient to satisfy consistency
level since until it is part of the read set it does not count towards CL on
reads.
* Writes acked by B must *not* be treated as sufficient to satisfy consistency
level *unless* the same write is *also* acked by D, because once D enters the
ring, B will no longer be counting towards CL on reads. The only alternative is
to make the read succeed and disallow D from entering the ring.
We don't seem to be handling this at all (and it becomes more complicated with
arbitrary transitions).
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
