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Sylvain Lebresne commented on CASSANDRA-4784:
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bq. I do still see this as useful for backup/restore in the general case though
While I kind of agree, I want to note that backuping data from only one replica
runs the risk of missing whatever data on which the node is not consistent,
unless you've run a repair just before. I suppose some may prefer just running
the repair prior to the backing or, especially if they are running regular
repairs, consider that good enough, but just wanted to note that at least in
theory that's not completely bulletproof.
> Create separate sstables for each token range handled by a node
> ---------------------------------------------------------------
>
> Key: CASSANDRA-4784
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4784
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: sankalp kohli
> Priority: Minor
> Labels: perfomance
>
> Currently, each sstable has data for all the ranges that node is handling. If
> we change that and rather have separate sstables for each range that node is
> handling, it can lead to some improvements.
> Improvements
> 1) Node rebuild will be very fast as sstables can be directly copied over to
> the bootstrapping node. It will minimize any application level logic. We can
> directly use Linux native methods to transfer sstables without using CPU and
> putting less pressure on the serving node. I think in theory it will be the
> fastest way to transfer data.
> 2) Backup can only transfer sstables for a node which belong to its primary
> keyrange.
> 3) ETL process can only copy one replica of data and will be much faster.
> Changes:
> We can split the writes into multiple memtables for each range it is
> handling. The sstables being flushed from these can have details of which
> range of data it is handling.
> There will be no change I think for any reads as they work with interleaved
> data anyway. But may be we can improve there as well?
> Complexities:
> The change does not look very complicated. I am not taking into account how
> it will work when ranges are being changed for nodes.
> Vnodes might make this work more complicated. We can also have a bit on each
> sstable which says whether it is primary data or not.
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