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https://issues.apache.org/jira/browse/CASSANDRA-17187?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benjamin Lerer updated CASSANDRA-17187:
---------------------------------------
Labels: lhf (was: AdventCalendar2021 lhf)
> Guardrail for SELECT IN terms and their cartesian product
> ---------------------------------------------------------
>
> Key: CASSANDRA-17187
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17187
> Project: Cassandra
> Issue Type: New Feature
> Components: Feature/Guardrails
> Reporter: Andres de la Peña
> Assignee: Andres de la Peña
> Priority: Normal
> Labels: lhf
> Fix For: 4.x
>
>
> Add a guardrail to limit the number restrictions generated by the cartesian
> product of the {{IN}} restrictions of a {{SELECT}} query, for example:
> {code}
> # Guardrail to warn or abort when IN query creates a cartesian product with a
> # size exceeding threshold, eg. "a in (1,2,...10) and b in (1,2...10)"
> results in
> # cartesian product of 100.
> # The two thresholds default to -1 to disable.
> in_select_cartesian_product:
> warn_threshold: -1
> abort_threshold: -1
> {code}
> As an example of why this guardrails is proposed, these queries bring a C*
> instance to its knees even before the query starts executing:
> {code}
> @Test
> public void testPartitionKeyTerms() throws Throwable
> {
> createTable("CREATE TABLE %s (pk1 int, pk2 int, pk3 int, pk4 int, pk5
> int, pk6 int, pk7 int, pk8 int, pk9 int, " +
> "PRIMARY KEY((pk1, pk2, pk3, pk4, pk5, pk6, pk7, pk8, pk9)))");
> execute("SELECT * FROM %s WHERE pk1 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND pk2 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND pk3 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND pk4 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND pk5 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND pk6 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND pk7 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND pk8 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND pk9 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10);");
> }
> @Test
> public void testClusteringKeyTerms() throws Throwable
> {
> createTable("CREATE TABLE %s (pk int ,ck1 int, ck2 int, ck3 int, ck4 int,
> ck5 int, ck6 int, ck7 int, ck8 int, ck9 int, " +
> "PRIMARY KEY(pk, ck1, ck2, ck3, ck4, ck5, ck6, ck7, ck8, ck9))");
> execute("SELECT * FROM %s WHERE pk = 1 " +
> "AND ck1 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND ck2 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND ck3 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND ck4 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND ck5 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND ck6 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND ck7 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND ck8 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10) " +
> "AND ck9 in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10);");
> }
> {code}
> +Additional information for newcomers:+
> # Add the configuration for the new guardrail on cartesian product in the
> guardrails section of cassandra.yaml.
> # Add a {{getInCartesianProduct}} method in {{GuardrailsConfig}} returning a
> {{Threshold.Config}} object
> # Implement that method in {{GuardrailsOptions}}, which is the default
> yaml-based implementation of {{GuardrailsConfig}}
> # Add a Threshold guardrail named {{inCartesianProduct}} in Guardrails, using
> the previously created config
> # Define JMX-friendly getters and setters for the previously created config
> in {{GuardrailsMBean}}
> # Implement the JMX-friendly getters and setters in Guardrails
> # Now that we have the guardrail ready, it’s time to use it. We should search
> for a place to invoke the Guardrails#inCartesianProduct guard method. The
> {{MultiCBuilder}} look like good candidates for this.
> # Finally, add some tests for the new guardrail. Given that the new guardrail
> is a Threshold, our new test should probably extend {{ThresholdTester}}.
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