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https://issues.apache.org/jira/browse/CASSANDRA-21539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18111187#comment-18111187
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Francisco Guerrero commented on CASSANDRA-21539:
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I'm in favor or reverting this change and rethinking how we want to address the
fix. We should not release a breaking change in a new build (Like David said,
we've been affected).
I'd argue that this belongs in the public API since we've documented it
publicly:
https://cassandra.apache.org/doc/4.1/cassandra/new/virtualtables.html#settings-virtual-table.
Anyone that read the documentation would have found this table and could be
relying on it.
bq. We also should create check style as this isn't the first time this DNS
lookup has hit us; its been a issue in the past with inet type... its way too
easy to do the wrong thing.
Yes , +1 to having this as a checkstyle rule
bq. I would like to have these things clarified once for all, I do not think we
have ever formally codified what a public API is and it seems to be an ongoing
argument.
Also, +1 on finding ways to improve this.
> Querying system_views.clients causes a DNS lookup for each unique connected
> client address
> ------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-21539
> URL: https://issues.apache.org/jira/browse/CASSANDRA-21539
> Project: Apache Cassandra
> Issue Type: Bug
> Components: Feature/Virtual Tables
> Reporter: Nivy Kani
> Assignee: Nivy Kani
> Priority: Normal
> Fix For: 4.0.22, 4.1.13, 5.0.10, 6.0-alpha3, 7.0
>
> Attachments: 4.0-ci_summary.html, 4.0-result_details.tar.gz.zip,
> 5.0-ci_summary.html, 5.0-result_details.tar.gz, 6.0-ci_summary.html,
> 6.0-result_details.tar.gz, ci_summary-1.html, ci_summary.html,
> result_details.tar-1.gz, result_details.tar.gz
>
> Time Spent: 1h 40m
> Remaining Estimate: 0h
>
> It looks like queries to the system_views.clients table does a DNS lookup for
> each unique address:
> https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/db/virtual/ClientsTable.java#L91
>
> Given Java's internal DNS caches, this is really only potentially slow on the
> first query, but we should avoid doing DNS lookups here as a workflow that
> queries this table on each node to collect client information could
> potentially overwhelm DNS this way.
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