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https://issues.apache.org/jira/browse/CASSANDRA-21539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18111190#comment-18111190
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Stefan Miklosovic commented on CASSANDRA-21539:
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Alright, look, I think that we should just revert this and if we do want to do
anything else with it we can always return to that after discussions are
resolved, if we start any. The most urgent thing so far is that this si not
released, which, thanks god, is not yet.
I would still mention in NEWS.txt for each branch this is in that this might be
resolving and it might have undesirable consequence of stressing DNS too much,
hypothetically. That way people _might_ modify their queries and omit this
particular column if they find it problematic. Until now they probably haven't
even known about it.
Deal?
> 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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