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From "Aleksey Yeschenko (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-10050) Secondary Index Performance Dependent on TokenRange Searched in Analytics
Date Fri, 23 Oct 2015 15:49:28 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-10050?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Aleksey Yeschenko updated CASSANDRA-10050:
------------------------------------------
    Issue Type: Improvement  (was: Bug)

> Secondary Index Performance Dependent on TokenRange Searched in Analytics
> -------------------------------------------------------------------------
>
>                 Key: CASSANDRA-10050
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-10050
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>         Environment: Single node, macbook, 2.1.8
>            Reporter: Russell Alexander Spitzer
>             Fix For: 3.x
>
>
> In doing some test work on the Spark Cassandra Connector I saw some odd performance when
pushing down range queries with Secondary Index filters. When running the queries we see huge
amount of time when the C* server is not doing any work and the query seem to be hanging.
This investigation led to the work in this document
> https://docs.google.com/spreadsheets/d/1aJg3KX7nPnY77RJ9ZT-IfaYADgJh0A--nAxItvC6hb4/edit#gid=0
> The Spark Cassandra Connector builds up token range specific queries and allows the user
to pushdown relevant fields to C*. Here we have two indexed fields (size) and (color) being
pushed down to C*. 
> {code}
> SELECT count(*) FROM ks.tab WHERE token("store") > $min AND token("store") <= $max
AND color = 'red' AND size = 'P' ALLOW FILTERING;{code}
> These queries will have different token ranges inserted and executed as separate spark
tasks. Spark tasks with token ranges near the Min(token) end up executing much faster than
those near Max(token) which also happen to through errors.
> {code}
> Coordinator node timed out waiting for replica nodes' responses] message="Operation timed
out - received only 0 responses." info={'received_responses': 0, 'required_responses': 1,
'consistency': 'ONE'}
> {code}
> I took the queries and ran them through CQLSH to see the difference in time. A linear
relationship is seen based on where the tokenRange being queried is starting with only 2 second
for queries near the beginning of the full token spectrum and over 12 seconds at the end of
the spectrum. 
> The question is, can this behavior be improved? or should we not recommend using secondary
indexes with Analytics workloads?



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