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Alexey Zotov commented on CASSANDRA-4768:
-----------------------------------------
Jonathan, if we're talking about latency, that you're right. We discussed that
in CASSANDRA-4761.
Now we're talking about size of hints CF. For local failed node we should store
much less hints that for whole remote DC. Lack of connectivity to remote DC is
not a common problem, but it could happen. The new option should save us from
"overfull" of hints CF in that case. Saying "overfull" I mean the following
cases:
1. if we use populate_io_cache_on_flush option hints will use part of memory
until they wont be supplanted by another data. It's actual until CASSANDRA-4694
is not resolved.
2. if we don't have a lot of free space on disc (it can be reserved by
compaction processes)
Let me remind that amount of hints for remote DC could be a huge in case of
large count of write/update operations.
Brandon, yes, we have to repair anyway if the remote hint window has been
exceeded.
We've thought and decided that it really can help only in the specific use
cases, e.g. with master-slave data centers (when write to one, read from all).
Actually we think that the new option is not necessary for us and we leave
decision to include or not include it to your notice.
> Add separate max_hint_window_in_ms option for remote data centers
> -----------------------------------------------------------------
>
> Key: CASSANDRA-4768
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4768
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 1.1.2
> Reporter: Alexey Zotov
> Assignee: Alexey Zotov
> Priority: Minor
> Labels: configuration, hintedhandoff
> Fix For: 1.1.7
>
> Attachments: cassandra-1.1-4768-remote_hint_window.txt,
> cassandra-1.2-4768-remote_hint_window.txt
>
>
> It would be nice to have possibility to configure hint window size for remote
> dc separately. It will allow to prevent accumulating of big amount of data
> for remote dc and long hints delivery as the result of it.
> I suggest to add max_hint_window_for_remote_dc_in_ms option.
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