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Jonathan Ellis commented on CASSANDRA-5722:
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bq. is the cost of decorating index keys so high that it outweighs the savings
from exiting the loop earlier when a greater key is found?
That's exactly what we want to do, and that's what the
{{indexDecoratedKey.compareTo(position) > 0}} check does for us. The part I
removed allows us to skip this check when we don't find key greater than the
position before we've finished the block where such a key would exist, i.e., it
saves us exactly one iteration of the loop [since the first key out of the next
block is guaranteed to be greater].
I thought that fell into the category of premature optimization and took it out
so it was more clear what we're doing. Did I miss something?
> Cleanup should skip sstables that don't contain data outside a nodes ranges
> ---------------------------------------------------------------------------
>
> Key: CASSANDRA-5722
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5722
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Nick Bailey
> Assignee: Tyler Hobbs
> Fix For: 2.0.1
>
> Attachments: 0001-Skip-cleanup-when-unneeded.patch
>
>
> Right now cleanup is optimized to simply delete sstables that *only* contain
> data that doesn't belong on the node, for all other sstables though, it will
> read them, check each row, and write out new sstables.
> Cleanup could be optimized to look at an sstable and determine that all data
> within the sstable does belong on a node, and therefore skip re-writing that
> sstable. This would make cleanup essentially a noop in the case where all
> data on a node belongs on that node.
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