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From "Sandeep Tata (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-195) Improve bootstrap algorithm
Date Tue, 18 Aug 2009 20:08:14 GMT


Sandeep Tata commented on CASSANDRA-195:

Here's the scenario for why forwarding logic will need to know the set of bootstrapNodes:

We have node A, B, C and the new node enters between B and C to get: A, B, N, C.
Say we use B (among other nodes) to bootstrap the data on N.

We still want to be able to forward writes that arrive at P, Q, R, etc intended for A B C
or B C D to reach A B N C. Which means every node needs to know the nodes that are being bootstrapped
and their locations on the ring (not just the nodes that are bootstrapping the new node which
know what ranges they are sending N). That's why we're storing the bootstrapNodes in tokenMetadata.

When insert or insertBlocking ask for R storage endpoints, we want to pick R + bootstrapping
nodes to receive the update.

> Improve bootstrap algorithm
> ---------------------------
>                 Key: CASSANDRA-195
>                 URL:
>             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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