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https://issues.apache.org/jira/browse/CASSANDRA-195?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12744619#action_12744619
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Sandeep Tata edited comment on CASSANDRA-195 at 8/18/09 11:03 AM:
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>>I don't see where this fixes the
>>serve-reads-from-the-old-nodes-until-bootstrap-complete problem, can you give
>>a high-level summary of how that works?
The tokenMetadata_.update calls now requires a bootstrap flag. If this flag is
true, the new node is added to a separate set bootstrapNodes and does not
affect calculations for sending reads and *writes*.
The node only surfaces in the ring once bootstrap is completed. The new node
will *not* have the writes that arrived during bootstrap -- a consequence of
the changes that accommodate the replication=1 case. We will need writes to see
a different ring (different result for getStorageEndPoints) than the reads --
that's not in this patch.
>>maybe I don't understand how this works -- to me that looks like if we send
>>any update about a node, everyone will clear the bootstrap flag on it, unless
>>we explicitly set bootstrap to true. shouldn't we only update bootstrap
>>status when it's explicitly set to true or false?
Hmm, I thought the gossiper always sent the full endpoint state, so it should
always include bootstrap status. If it isn't sent, it means the node is not
bootstrapping. See Gossiper.GossipDigestAckVerbHandler
Even otherwise, if oldToken == newToken, the only action taken is deliverHints.
The bootstrap status is not cleared.
was (Author: sandeep_tata):
>>I don't see where this fixes the
serve-reads-from-the-old-nodes-until-bootstrap-complete problem, can you give a
high-level summary of how that works?
The tokenMetadata_.update calls now requires a bootstrap flag. If this flag is
true, the new node is added to a separate set bootstrapNodes and does not
affect calculations for sending reads and *writes*.
The node only surfaces in the ring once bootstrap is completed. The new node
will *not* have the writes that arrived during bootstrap -- a consequence of
the changes that accommodate the replication=1 case. We will need writes to see
a different ring (different result for getStorageEndPoints) than the reads --
that's not in this patch.
>>maybe I don't understand how this works -- to me that looks like if we send
>>any update about a node, everyone will clear the bootstrap flag on it, unless
>>we explicitly set bootstrap to true. shouldn't we only update bootstrap
>>status when it's explicitly set to true or false?
Hmm, I thought the gossiper always sent the full endpoint state, so it should
always include bootstrap status. If it isn't sent, it means the node is not
bootstrapping. See:
Gossiper.makeRandomGossipDigest:
EndPointState epState = endPointStateMap_.get(localEndPoint_);
Even otherwise, if oldToken == newToken, the only action taken is deliverHints.
The bootstrap status is not cleared.
> Improve bootstrap algorithm
> ---------------------------
>
> Key: CASSANDRA-195
> URL: https://issues.apache.org/jira/browse/CASSANDRA-195
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Environment: all
> Reporter: Sandeep Tata
> Assignee: Sandeep Tata
> Fix For: 0.5
>
> Attachments: 195-v1.patch, 195-v2.patch, 195-v3-delta1.patch,
> 195-v3.patch, 195-v4.patch
>
>
> When you add a node to an existing cluster and the map gets updated, the new
> node may respond to read requests by saying it doesn't have any of the data
> until it gets the data from the node(s) the previously owned this range (the
> load-balancing code, when working properly can take care of this). While this
> behaviour is compatible with eventual consistency, it would be much
> friendlier for the new node not to "surface" in the EndPoint maps for reads
> until it has transferred the data over from the old nodes.
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