[
https://issues.apache.org/jira/browse/CASSANDRA-1608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12965158#action_12965158
]
Oleg Anastasyev commented on CASSANDRA-1608:
--------------------------------------------
Ryan: yes, the idea is exactly in splitting sstables by uniform token ranges.
So, if total node's data is 4Gb and you split to 2 subranges, after major
compaction you'll have 2 sstables, each with size around 2gb-4gb. If you split
to 256 subranges, you'll have 256 sstables. It is unlikely, that any one of
them will be close to 4gb otherwise your cluster is very badly unbalanced and
you should rethink what you're really doing.
IMHO it it much better to have 256 subranges by node than 2. No negative effect
on performance, but compactions as well as disk space management become much
lighter.
> 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.
