englefly opened a new pull request, #18129: URL: https://github.com/apache/doris/pull/18129
# Proposed changes in this pr, we add a new algorithm to estimate semi/anti join row count. In original alg., we reduce row count from cross join. usually, this is not good. for example, L left semi join R on L.a=R.a suppose L is larger than R, and ndv(L.a) < ndv(R.a) the estimated row count is rowcount(R) * rowcount(L) / ndv(R.a). in most cases, the estimated row count is larger than rowcount(L). in new alg, we use ndv(R.a)/originalNdv(R.a) to estimate result rowCount Issue Number: close #xxx ## Problem summary Describe your changes. ## Checklist(Required) * [ ] Does it affect the original behavior * [ ] Has unit tests been added * [ ] Has document been added or modified * [ ] Does it need to update dependencies * [ ] Is this PR support rollback (If NO, please explain WHY) ## Further comments If this is a relatively large or complex change, kick off the discussion at [[email protected]](mailto:[email protected]) by explaining why you chose the solution you did and what alternatives you considered, etc... -- 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]
