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From "Ryan King (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-1657) support in-memory column families
Date Wed, 02 Feb 2011 00:44:29 GMT


Ryan King commented on CASSANDRA-1657:

For narrow SSTables, shouldn't the row cache be enough for this?

> support in-memory column families
> ---------------------------------
>                 Key: CASSANDRA-1657
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Peter Schuller
>            Priority: Minor
> Some workloads are such that you absolutely depend on column families being in-memory
for performance, yet you most definitely want all the things that Cassandra offers in terms
of replication, consistency, durability etc.
> In order to semi-deterministically ensure acceptable performance for such data, Cassandra
could support in-memory column families. Such an in-memory column family would imply that
mlock() be used on sstables for this column family. On start-up and on compaction completion,
they could be mmap():ed with MAP_POPULATE (Linux specific) or else just mmap():ed + mlock():ed
in such a way as to otherwise guarantee it is in-memory (such as userland traversal of the
entire file).

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