Steve Carlin has posted comments on this change. ( http://gerrit.cloudera.org:8080/23311 )
Change subject: IMPALA-14101: [part 2] Calcite planner: Add cost model calculations ...................................................................... Patch Set 2: (3 comments) http://gerrit.cloudera.org:8080/#/c/23311/2//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/23311/2//COMMIT_MSG@9 PS2, Line 9: This commit adds the cost model and calculations to be used in the join : optimizer rule. > nit: Please help with short explanation on how this costing will impact res I hope I answered your question with the latest commit message The join optimizer rule basically calculates a cost of a given join order using these costs. Essentially giving a number for cpu and io usage. As I type my comment now, I realize that perhaps I should have used the word "time" instead of "cost"? Essentially we're trying to calculate the time it takes for the specific join order to run by using the cpu and io time. We can then compare two join orders and take the one whose cost (time) is less. Does that make sense? Should I add that "cost" is basically "time" in the commit message or perhaps in the file itself? http://gerrit.cloudera.org:8080/#/c/23311/2//COMMIT_MSG@14 PS2, Line 14: rowCount cost. > Why is rowCount omitted? Added a comment for this, and also see my answer to Riza's comment. Row count is already baked into the cpu time/cost and io time/cost. To compare row counts doesn't really make sense. http://gerrit.cloudera.org:8080/#/c/23311/2//COMMIT_MSG@16 PS2, Line 16: The ImpalaCost object is generated in the ImpalaRelMdNonCumulativeCost : class which is called from Calcite for a given RelNode. > nit: Please mention a bit about which query operator that has implemented c Changed the comment...is it enough? Yes, this is also only single node planning (which is all Calcite does at the current time) so no BROADCAST or HASH decision is calculated in this portion. -- To view, visit http://gerrit.cloudera.org:8080/23311 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I1e52b0e11e9a6d5814b0313117dd9c56602f3ff5 Gerrit-Change-Number: 23311 Gerrit-PatchSet: 2 Gerrit-Owner: Steve Carlin <[email protected]> Gerrit-Reviewer: Aman Sinha <[email protected]> Gerrit-Reviewer: Fang-Yu Rao <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Joe McDonnell <[email protected]> Gerrit-Reviewer: Michael Smith <[email protected]> Gerrit-Reviewer: Riza Suminto <[email protected]> Gerrit-Reviewer: Steve Carlin <[email protected]> Gerrit-Comment-Date: Fri, 29 Aug 2025 00:18:48 +0000 Gerrit-HasComments: Yes
