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https://issues.apache.org/jira/browse/CASSANDRA-4175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13699208#comment-13699208
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Jonathan Ellis commented on CASSANDRA-4175:
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{quote}
Has it become easier to get to know sstable version numbers in the serializer
class now?
I could maybe check if someone in the team here would like to take a stab at
moving this to latest cassandra and commit it if the above implementation seems
interesting.
{quote}
That would be great. Yes, you'll see Descriptor.Version being passed around
now which is what encapsulates what kind of sstable it is, including to the
lowest level of Column.onDiskIterator.
> Reduce memory, disk space, and cpu usage with a column name/id map
> ------------------------------------------------------------------
>
> Key: CASSANDRA-4175
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4175
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Jonathan Ellis
> Fix For: 2.1
>
>
> We spend a lot of memory on column names, both transiently (during reads) and
> more permanently (in the row cache). Compression mitigates this on disk but
> not on the heap.
> The overhead is significant for typical small column values, e.g., ints.
> Even though we intern once we get to the memtable, this affects writes too
> via very high allocation rates in the young generation, hence more GC
> activity.
> Now that CQL3 provides us some guarantees that column names must be defined
> before they are inserted, we could create a map of (say) 32-bit int column
> id, to names, and use that internally right up until we return a resultset to
> the client.
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