[GitHub] [incubator-doris] cambyzju commented on a diff in pull request #9688: [fix] group by with two NULL rows after left join

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

cambyzju commented on code in PR #9688:
URL: https://github.com/apache/incubator-doris/pull/9688#discussion_r876996911


##########
be/src/vec/columns/column_nullable.cpp:
##########
@@ -102,7 +102,10 @@ StringRef ColumnNullable::serialize_value_into_arena(size_t n, Arena& arena,
     static constexpr auto s = sizeof(arr[0]);
 
     auto pos = arena.alloc_continue(s, begin);
-    memcpy(pos, &arr[n], s);
+    // Value of `NULL` may be 1 or JOIN_NULL_HINT, we serialize both to 1.
+    // Because we need same key for both `NULL` values while processing `group by`.
+    UInt8* val = reinterpret_cast<UInt8*>(pos);
+    *val = (arr[n] ? 1 : 0);
 

Review Comment:
   done



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