[
https://issues.apache.org/jira/browse/CASSANDRA-1608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12925179#action_12925179
]
Stu Hood commented on CASSANDRA-1608:
-------------------------------------
> But I am concerned with strategies that imply having to keep significant
> amounts of data over time, such as anything based
> on row-level frequency/recency of access.
Although it probably sounds like I have bloom filter fever, we could use a
bloom filter for this as well: filters based on multisets, (spectral bloom
filters, count min sketches), allow storing approximate counts for values. The
access counts for rows for the lifetime of a memtable could be stored in a
filter attached to the memtable: at read time, the approximate access count of
the row key could be checked against a threshold of accesses, and be stored in
the memtable as superseding.
> Redesigned Compaction
> ---------------------
>
> Key: CASSANDRA-1608
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1608
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Chris Goffinet
> Fix For: 0.7.1
>
>
> After seeing the I/O issues in CASSANDRA-1470, I've been doing some more
> thinking on this subject that I wanted to lay out.
> I propose we redo the concept of how compaction works in Cassandra. At the
> moment, compaction is kicked off based on a write access pattern, not read
> access pattern. In most cases, you want the opposite. You want to be able to
> track how well each SSTable is performing in the system. If we were to keep
> statistics in-memory of each SSTable, prioritize them based on most accessed,
> and bloom filter hit/miss ratios, we could intelligently group sstables that
> are being read most often and schedule them for compaction. We could also
> schedule lower priority maintenance on SSTable's not often accessed.
> I also propose we limit the size of each SSTable to a fix sized, that gives
> us the ability to better utilize our bloom filters in a predictable manner.
> At the moment after a certain size, the bloom filters become less reliable.
> This would also allow us to group data most accessed. Currently the size of
> an SSTable can grow to a point where large portions of the data might not
> actually be accessed as often.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
