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From "David Semeria (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-7535) Coverage analysis for range queries
Date Fri, 11 Jul 2014 17:20:05 GMT


David Semeria commented on CASSANDRA-7535:

Brandon, 2.0.4 works as expected, try it with 2.0.9.

We have two DCs, one running 2.0.4 and the other running 2.0.9. Range scans are coming back
in around 10ms in DC1 (RF=3/n=3) and were taking anywhere between 200 and 1000ms in DC2 (RF=
5,n=5). When I put the 2.0.4 cassandra jar in DC2 the latencies disappeared. 

> Coverage analysis for range queries
> -----------------------------------
>                 Key: CASSANDRA-7535
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: David Semeria
>            Assignee: Tyler Hobbs
>             Fix For: 2.0.10
> This is a regression related to [CASSANDRA-4858|]
> Range queries are taking orders of magnitude more time to complete than before because
the query planner is frequently unable to calculate the correct intersection of contiguous
ranges for a given node.
> For example, SELECT * FROM TBL should result in exactly one scan at CL.ONE when RF =
#nodes when in fact it can result in several hundred scans (sometimes thousands). The problem
is exasperated with vnodes.
> The regression occurred at some point between 2.0.4 (which works fine) and 2.0.9.   

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