fix(tianmu):

    The current version does not enable multithreaded aggregation optimization,
    Here's why:
    Currently, for multi-thread parallel,
    it is not completely carried out to the physical layer,
    for DPN and PACK data structure,
    because the underlying physical block processing for multi-thread from the data structure support is missing,
    when a multi-thread switch occurs,
    the data that has been read out is reset.
    More time is needed to support parallel read IO across multiple threads from the underlying data structures,
    which is not available in the current version,
    so we plan to start the second phase of the multi-thread read IO process completely.

storage/tianmu/core/aggregation_algorithm.cpp

@@ -194,7 +194,7 @@ void AggregationAlgorithm::Aggregate(bool just_distinct, int64_t &limit, int64_t
     }
   } else {
     int64_t local_limit = limit == -1 ? upper_approx_of_groups : limit;
-    MultiDimensionalGroupByScan(gbw, local_limit, offset, sender, limit_less_than_no_groups, true);
+    MultiDimensionalGroupByScan(gbw, local_limit, offset, sender, limit_less_than_no_groups, false);
     if (limit != -1) limit = local_limit;
   }
   t->ClearMultiIndexP();  // cleanup (i.e. regarded as materialized,