DaZuiZui commented on PR #17960: URL: https://github.com/apache/iotdb/pull/17960#issuecomment-4861941714
Thanks for the detailed review and the measurements. I’ve addressed the performance/robustness issue you pointed out in the latest commit. The LCA rewrite no longer deep-copies/inlines the already-expanded expression from the previous alias. Instead, the planner reuses previous LCA projections through symbol mappings and appends SELECT projections in batches, so deep chained aliases should no longer cause the O(N^2) plan-expression / EXPLAIN JSON blowup. I also added regression tests for this case, including: - reusing a previous `CAST(...) AS x` projection without duplicating the Cast expression - a 200-column chained LCA case that keeps plan expressions shallow and the plan JSON bounded Verified with: ./mvnw test -pl iotdb-core/datanode -Dtest=SelectAliasReuseTest All 40 tests passed. Please take another look when you have time. -- 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]
