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From "Aleksey Yeschenko (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-9673) Improve batchlog write path
Date Tue, 14 Jul 2015 10:08:04 GMT


Aleksey Yeschenko commented on CASSANDRA-9673:

bq. 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.

No, we reuse {{REQUEST_RESPONSE}} for almost everything. You do create a new response message
class, but reuse the same verb. Look at the branch for CASSANDRA-6230 to see how {{HintResponse}}
is being handled.

bq. Another question is whether we need to introduce a new stage or is it OK to keep on using

We don't *need* to, but it might already have been done by CASSANDRA-6477.

bq. do we already have a ticket or plan for fixing compatibility with older nodes?


> 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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