gianm opened a new pull request, #18074: URL: https://github.com/apache/druid/pull/18074
Adds a new SQL context parameter to control whether TopN queries can use lexicographic dimension ordering. When false (the default), such queries become GroupBy queries instead, which are generally more efficient due to their ability to vectorize. Updates tests to either set useLexicographicTopN: true where TopN behavior is intentionally being tested, or to expect GroupBy queries. Requires an upgrade note about a behavior change: > This release now uses the `groupBy` native query type, rather than `topN`, for SQL queries that group > by and order by the same column, have LIMIT, and do no have HAVING. This is intended to speed up execution > of such queries, since `groupBy` is vectorized whereas `topN` is not. The former behavior can be restored > by setting `useLexicographicTopN` to `true`. Behavior for `useApproximateTopN` is unchanged, and the > default remains `true`. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
