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From "Jonathan Ellis (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-4175) Reduce memory (and disk) space requirements with a column name/id map
Date Thu, 19 Apr 2012 21:40:40 GMT
Reduce memory (and disk) space requirements with a column name/id map
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                 Key: CASSANDRA-4175
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4175
             Project: Cassandra
          Issue Type: Improvement
            Reporter: Jonathan Ellis
             Fix For: 1.2


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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