Github user jianqiao commented on a diff in the pull request: https://github.com/apache/incubator-quickstep/pull/171#discussion_r98545487 --- Diff: query_optimizer/PhysicalGenerator.cpp --- @@ -109,6 +114,13 @@ P::PhysicalPtr PhysicalGenerator::optimizePlan() { } else { rules.emplace_back(new SwapProbeBuild()); } + if (FLAGS_reorder_columns) { + // NOTE(jianqiao): This optimization relies on the fact that the intermediate + // relations all have SPLIT_ROW_STORE layouts. If this fact gets changed, the + // optimization algorithm may need to be updated and the performance impact + // should be re-evaluated. --- End diff -- Currently this cannot be checked because the temporary relations' layouts are generated in `ExecutionGenerator` when they get created. In the future we will reason about the layouts during query optimization and add corresponding data structures.
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