[GitHub] [incubator-doris] kangkaisen commented on a change in pull request #1854: Avoid SerDe for aggregation query with object pool

[GitBox <gi...@apache.org>]

kangkaisen commented on a change in pull request #1854: Avoid SerDe for aggregation query with object pool
URL: https://github.com/apache/incubator-doris/pull/1854#discussion_r327525250
 
 

 ##########
 File path: be/src/olap/aggregate_func.h
 ##########
 @@ -398,17 +401,21 @@ struct AggregateFuncTraits<OLAP_FIELD_AGGREGATION_REPLACE, OLAP_FIELD_TYPE_CHAR>
 // so when init, update hll, the src is not null
 template <>
 struct AggregateFuncTraits<OLAP_FIELD_AGGREGATION_HLL_UNION, OLAP_FIELD_TYPE_HLL> {
-    static void init(RowCursorCell* dst, const char* src, bool src_null, Arena* arena) {
+    static void init(RowCursorCell* dst, const char* src, bool src_null, Arena* arena, ObjectPool* agg_pool) {
         DCHECK_EQ(src_null, false);
         dst->set_not_null();
 
         auto* src_slice = reinterpret_cast<const Slice*>(src);
         auto* dst_slice = reinterpret_cast<Slice*>(dst->mutable_cell_ptr());
 
-        dst_slice->size = sizeof(HyperLogLog);
-        // use 'placement new' to allocate HyperLogLog on arena, so that we can control the memory usage.
-        char* mem = arena->Allocate(dst_slice->size);
-        dst_slice->data = (char*) new (mem) HyperLogLog((const uint8_t*)src_slice->data);
+        // we use int32_t max size represent this slice is a agg object
+        dst_slice->size = std::numeric_limits<int32_t>::max();
+        auto* hll = new HyperLogLog((const uint8_t*) src_slice->data);
+        dst_slice->data = reinterpret_cast<char*>(hll);
+
+        arena->track_memory(sizeof(HyperLogLog));
 
 Review comment:
   I agree with you.
   But this should be another issue,  This PR don't change this point.
   We need a better way to estimate the HLL and Bitmap memory usage.
   
   

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