Enable 'With Rollup' with Custom Dimension Reports under feature flag

[nathangavin]

Description:

Adds the WITH ROLLUP solution for Custom Dimension reports to improve aggregation accuracy while maintaining performance. New feature is wrapped in a feature flag.

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed

[nathangavin]

For some reason plugins/CustomDimensions/tests/System/ApiTest::testRankingLimit() is now producing different results each time it is run. @mneudert any idea why this might be?

[mneudert]

Those random failures are caused by the (now) missing COALESCE(), bringing back the randomness already documented in the BlobReportLimitingTest.

In the by_archiving_query dataset the SQL query is grouping values into the "Others" row. And the order of custom_dimension_1 + url results are quite random. If you run the ranking query used in that dataset multiple times you can nicely observe that randomness (you might need to reconnect to MySQL for each query run if you don't see random results).

I can see two solutions for this:

• skip that dataset with the feature flag inactive
• change the fixture to ensure the result is deterministic

Probably not a bad choice to just skip it, as the BlobReportLimitingTest already documented the randomness.

[nathangavin]

I decided to skip the test for the standard ranking query test.