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https://issues.apache.org/jira/browse/CASSANDRA-9673?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14726587#comment-14726587
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Stefania commented on CASSANDRA-9673:
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bq. I meant checking for table emptiness at the beginning of startup migration,
and logging once if not empty.
Right, makes more sense now.
bq. Also, the logic in conversion for != 1 uuids seems a bit weird. It will
never be the case that we'll get a mutation
The replay unit tests were still checking for 1.2 mutations.
bq. There was a bug in SP::syncWriteToBatchlog that is as old as is batchlog
itself. We are using CL.ONE unconditionally, even when we have two endpoints.
And both legacy/modern writes should be sharing the same callback, so I
switched back to using WriteResponseHandler for both.
Thanks for fixing this.
bq. I think I broke some replay tests.
I removed the 1.2 mutations from the replay tests. They are fine now.
Rebased again and force pushed, if the latest CI is good then I'm +1 as well:
http://cassci.datastax.com/view/Dev/view/stef1927/job/stef1927-9673-3.0-dtest/
http://cassci.datastax.com/view/Dev/view/stef1927/job/stef1927-9673-3.0-testall/
Thanks!
> Improve batchlog write path
> ---------------------------
>
> Key: CASSANDRA-9673
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9673
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Aleksey Yeschenko
> Assignee: Stefania
> Labels: performance
> Fix For: 3.0 beta 2
>
> Attachments: 9673_001.tar.gz, 9673_004.tar.gz,
> gc_times_first_node_patched_004.png, gc_times_first_node_trunk_004.png
>
>
> 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 it).
> 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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