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https://issues.apache.org/jira/browse/CASSANDRA-19529?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17836052#comment-17836052
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Nicolas Henneaux edited comment on CASSANDRA-19529 at 4/11/24 8:37 AM:
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I made some tracing and restart of the nodes executing the queries at the same
moment after restart. I don't see anything very conclusive anymore. Moreover
the graph is not very conclusive anymore despite a higher latency during warm
up but this is expected since using LOCAL_QUORUM.
I suspect the before was with a long running cluster and after restart it takes
some hours to warm-up everything.
!screenshot-4.png!
On another subject, I realize while playing with this change that LOCAL_QUORUM
might be a risky setup in my situation.
The setup is spread across 3 physical DC's with two close proximity (<1ms) DC's
and one at 10ms. Two Cassandra DC's are setup,one for close proximity physical
DC's (C*-DC1) and another for the other DC (C*-DC2). C*-DC1 has 4 nodes with
replication of 4 and C*-DC2 with replication of 1. They are working in QUORUM.
It allows the loss of two nodes without impact on the availability. With auth
using LOCAL_QUORUM, it does not allow such fail-over scenario.
was (Author: nicolas.henneaux):
I made some tracing and restart of the nodes executing the queries at the same
moment after restart. I don't see anything very conclusive anymore. Moreover
the graph is not very conclusive anymore despite a higher latency during warm
up but this is expected since using LOCAL_QUORUM.
I suspect the before was with a long running cluster and after restart it takes
some hours to warm-up everything.
!screenshot-4.png!
> Latency regression on 4.1 comparing to 4.0
> ------------------------------------------
>
> Key: CASSANDRA-19529
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19529
> Project: Cassandra
> Issue Type: Bug
> Components: Feature/Authorization
> Reporter: Nicolas Henneaux
> Priority: Normal
> Fix For: 4.1.x, 5.0.x, 5.x
>
> Attachments: screenshot-1.png, screenshot-2.png, screenshot-3.png,
> screenshot-4.png
>
>
> When upgrading from Cassandra 4.0.10 to 4.1.3, I noticed an increase from
> application point of view latency from ~8ms to ~15ms when upgrading to
> Cassandra. The latency includes 3 simple queries (INSERT + SELECT (PK+CK) +
> UPDATE) plus application overhead.
> It has been investigated in CASSANDRA-18766 to realize it is not related.
> I tested to downgrade to 4.1alpha1 and the latency regression is still there
> with same value.
> The version 4.1.4 has the same issue.
> In a graph how it looks like
> !screenshot-1.png!
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