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From "Hudson (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-1046) optimize Memtable.getSliceIterator
Date Sat, 05 Jun 2010 12:47:58 GMT


Hudson commented on CASSANDRA-1046:

Integrated in Cassandra #456 (See [])
    optimize away copy of sliced row on memtable read path.  patch by mdennis; reviewed by
jbellis for CASSANDRA-1046

> optimize Memtable.getSliceIterator
> ----------------------------------
>                 Key: CASSANDRA-1046
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jonathan Ellis
>            Assignee: Matthew F. Dennis
>             Fix For: 0.7
>         Attachments: 0001-trunk-cassandra-1046.patch,,
> As reported by James Golick, about 30% of the time in a read is spent in SliceQueryFilter.getMemColumnIterator,
virtually all of which is in ConcurrentSkipListMap$Values.toArrray().
> I wrote on the ML:
> Besides the UUID optimization you posted, we should do an audit of ColumnFamily.getSortedColumns
and replace with iteration where possible (in this case, we'd be left with one copy of most
of the columns, but that's better than two).
> We can get rid of the other copy by fixing the logic in Memtable.getSliceIterator, which
says "copy all the columns, so we can do a binary search on them to find where to start,"
but since columns are natively in sorted order we could just use an iterator and a while loo

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