[
https://issues.apache.org/jira/browse/CASSANDRA-7282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14132924#comment-14132924
]
Joshua McKenzie commented on CASSANDRA-7282:
--------------------------------------------
{quote}
does factor in to the decision
{quote}
{quote}
1) what workloads / portions of workloads are affected;
{quote}
That's what I was referring to.
To be clear: I'm not saying we shouldn't use the container or that I'm against
it in any way, I'm just re-iterating that we need to be clear as to which
use-cases and configurations we expect this to help with (which you've done)
and weigh that relative to the added risk of untested code and the added
complexity associated with the change.
> Faster Memtable map
> -------------------
>
> Key: CASSANDRA-7282
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7282
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Benedict
> Assignee: Benedict
> Labels: performance
> Fix For: 3.0
>
> Attachments: profile.yaml, reads.svg, run1.svg, writes.svg
>
>
> Currently we maintain a ConcurrentSkipLastMap of DecoratedKey -> Partition in
> our memtables. Maintaining this is an O(lg(n)) operation; since the vast
> majority of users use a hash partitioner, it occurs to me we could maintain a
> hybrid ordered list / hash map. The list would impose the normal order on the
> collection, but a hash index would live alongside as part of the same data
> structure, simply mapping into the list and permitting O(1) lookups and
> inserts.
> I've chosen to implement this initial version as a linked-list node per item,
> but we can optimise this in future by storing fatter nodes that permit a
> cache-line's worth of hashes to be checked at once, further reducing the
> constant factor costs for lookups.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
