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From "Alan Boudreault (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6477) Materialized Views (was: Global Indexes)
Date Fri, 10 Jul 2015 19:46:09 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14622809#comment-14622809
] 

Alan Boudreault commented on CASSANDRA-6477:
--------------------------------------------

Okay, I've been working on these comparisons but haven't been able to provide useful results
due to an issue I hit. I am doing my benchmarks on ec2 with a cluster of 3 nodes. Basically,
I can get realistic and useful results with C* stock (no MV) and C* with a Secondary Index
( between 70000 and 85000 op/s). When it comes to testing C* with 1 MV, I got many many WriteTimeoutExceptions
which results in a performance of 100 operations per second. I have been able to reproduce
that 100 op/s locally using a 3 nodes cluster. The issue doesn't seem to be present when using
a single node cluster.  

I've profiled one of the node and it looks like most of the time is spend in io.netty.channel.epoll.EpollEventLoop.epollWait()
(like 75% of the time).  

Here's a yourkit snapshot of the first node of the cluster.
http://dl.alanb.ca/CassandraDaemon-cluster-3-nodes-2015-07-10.snapshot.zip

I've attached my users.yaml profile that I am using for testing: [^users.yaml]

Here's the materialized view creation statement:
{code}
CREATE MATERIALIZED VIEW perftesting.users_by_first_name AS SELECT * FROM perftesting.users
PRIMARY KEY (first_name);
{code}

Here's the stress command I've been using:
{code}
cassandra-stress user profile=/path/to/users.yaml ops\(insert=1\) n=5000000 no-warmup -pop
seq=1..200M  no-wrap -rate threads=200 -node 127.0.0.1,127.0.0.2,127.0.0.3
{code}


Let me know if I am doing anything wrong or if I can provide anything else to help. I'll provide
the benchmarks as soon as I have a workaround for this issue.

> Materialized Views (was: Global Indexes)
> ----------------------------------------
>
>                 Key: CASSANDRA-6477
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6477
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: API, Core
>            Reporter: Jonathan Ellis
>            Assignee: Carl Yeksigian
>              Labels: cql
>             Fix For: 3.0 beta 1
>
>         Attachments: test-view-data.sh
>
>
> Local indexes are suitable for low-cardinality data, where spreading the index across
the cluster is a Good Thing.  However, for high-cardinality data, local indexes require querying
most nodes in the cluster even if only a handful of rows is returned.



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