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From "Stefania (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-9673) Improve batchlog write path
Date Tue, 14 Jul 2015 10:02:05 GMT


Stefania commented on CASSANDRA-9673:

[~iamaleksey] do we also need a BATCH_RESPONSE verb or should we just keep on using REQUEST_RESPONSE?
I've added BATCH_RESPONSE but it is functionally identical to REQUEST_RESPONSE. The same goes
for the handler, WriteResponseHandler, which I have not duplicated instead. Another question
is whether we need to introduce a new stage or is it OK to keep on using Stage.MUTATION?

I started writing dtest to check that we can still support older nodes, e.g. 2.2, but things
are quite broken at the moment, for example in ReadCommand serializer:

if (version < MessagingService.VERSION_30)
    throw new UnsupportedOperationException();

cc [~slebresne] - do we already have a ticket or plan for fixing compatibility with older

> Improve batchlog write path
> ---------------------------
>                 Key: CASSANDRA-9673
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Aleksey Yeschenko
>            Assignee: Stefania
>             Fix For: 3.0.0 rc1
> Currently we allocate an on-heap {{ByteBuffer}} to serialize the batched mutations into,
before sending it to a distant node, generating unnecessary garbage (potentially a lot of
> With materialized views using the batchlog, it would be nice to optimise the write path:
> - introduce a new verb ({{Batch}})
> - introduce a new message ({{BatchMessage}}) that would encapsulate the mutations, expiration,
and creation time (similar to {{HintMessage}} in CASSANDRA-6230)
> - have MS serialize it directly instead of relying on an intermediate buffer
> To avoid merely shifting the temp buffer to the receiving side(s) we should change the
structure of the batchlog table to use a list or a map of individual mutations.

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