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From zuyu <...@git.apache.org>
Subject [GitHub] incubator-quickstep pull request #171: QUICKSTEP-68 Reorder intermediate rel...
Date Mon, 30 Jan 2017 06:54:54 GMT
Github user zuyu commented on a diff in the pull request:

    --- 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 --
    I suggest to check this assumption in `ReorderColumns::IsTransformable`, so we could remove
this comment here.

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