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https://issues.apache.org/jira/browse/CASSANDRA-6731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13905570#comment-13905570
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Ryan McGuire commented on CASSANDRA-6731:
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I've attached a script (ticket_6731.py) that runs a few tests:
* local_read_speed_test_without_shutdown
* local_read_speed_test_with_shutdown
* test_local_read_trace
The first two perform a small speed run comparing the case of one node vs three
nodes. The single node test was a few seconds faster (average 37.8s for 1 node
vs 42.5s for 3 nodes.)
test_local_read_trace does things more methodically, and runs a trace on each
query to determine what percentage of queries actually contact nodes other than
the coordinator. Of a sample set of 1000 queries, 10.7% of them contacted other
nodes. You can see those traces in 6731.traces.txt.
So, I do concur that a non-negligible amount of the queries do contact other
nodes, but it doesn't appear to have much of a performance impact. This test
was done on a local ccm cluster, so it may warrant testing on a physical
cluster with different data loads.
[~arisp] can you post your schema and your approximate data size?
> Requests unnecessarily redirected with CL=ONE
> ---------------------------------------------
>
> Key: CASSANDRA-6731
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6731
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Environment: Linux
> Reporter: Aris Prassinos
> Assignee: Ryan McGuire
> Attachments: 6731.traces.txt, ticket_6731.py
>
>
> Three-node cluster with RF=3. All data currently in sync.
> Network topology strategy. Each node defined to be on a different rack.
> endpoint_snitch: PropertyFileSnitch
> dynamic_snitch_update_interval_in_ms: 100
> dynamic_snitch_reset_interval_in_ms: 600000
> dynamic_snitch_badness_threshold: 0
> All tables defined with read_repair_chance=0
> From cqlsh when querying with Consistency=ONE tracing shows that requests get
> frequently redirected to other nodes even though the local node has the data.
> There is no other activity on the cluster besides my test queries.
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