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https://issues.apache.org/jira/browse/CASSANDRA-4175?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis resolved CASSANDRA-4175.
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Resolution: Duplicate
Assignee: (was: Jason Brown)
Fix Version/s: (was: 3.x)
Column name duplication is removed in CASSANDRA-8099. (See
https://github.com/pcmanus/cassandra/blob/8099_engine_refactor/guide_8099.md.)
(We can do slightly better by encoding column ids in the schema, but doing in
on a per-sstable basis is almost as good from a disk space perspective.)
IMO we should leave dealing with highly duplicated column *values* to the
compression layer.
> 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
> Labels: performance
>
> 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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