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https://issues.apache.org/jira/browse/CASSANDRA-51?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12697928#action_12697928
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Jonathan Ellis edited comment on CASSANDRA-51 at 4/10/09 12:13 PM:
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Right. I think that NameSortColumnFamily and TimeSortColumnFamily might not be
a bad specialization to make. For us at least we will use a lot more name
sorted so gaining efficiency there is worth a little effort. But this should
wait until we have a performance test.
was (Author: jbellis):
Right. I think that NameSortColumn and TimeSortColumn might not be a bad
specialization to make. For us at least we will use a lot more name sorted so
gaining efficiency there is worth a little effort. But this should wait until
we have a performance test.
> Memory footprint for memtable
> ------------------------------
>
> Key: CASSANDRA-51
> URL: https://issues.apache.org/jira/browse/CASSANDRA-51
> Project: Cassandra
> Issue Type: Improvement
> Environment: all
> Reporter: Sandeep Tata
> Assignee: Eric Evans
> Fix For: 0.3
>
>
> The implementation of EfficientBidiMap(EBM) today stores the column in two
> place, a map and a sorted set. Both data structures store exactly the same
> values.
> I assume we're storing this twice so that the map can give us O(1) reads
> while the sortedset is important for efficient flush. Is this tradeoff
> important ? Do we want to store the data twice to get O(1) reads over
> O(log(n)) reads from sortedset? Is the sortedset implementation broken?
> Perhaps we should consider a configuration option that turns off the map --
> write performance will be slightly improved, read performance will be
> somewhat worse, and the memory footprint will probably be about half.
> Certainly sounds like a good alternative tradeoff.
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