Separate def level and rep level handling

cpp/src/parquet/column_reader.cc

@@ -1699,27 +1699,28 @@ class TypedRecordReader : public TypedColumnReaderImpl<DType>,
 
     // Count logical records and number of non-null values to read
     ARROW_DCHECK(!at_record_start_);
+    // Scan repetition levels to find record end
+    int64_t level = levels_position_;
     while (levels_position_ < levels_written_) {
       int64_t stride =
           std::min(levels_written_ - levels_position_, num_records - records_read);
       const int64_t position_end = levels_position_ + stride;
       for (int64_t i = levels_position_; i < position_end; ++i) {
         records_read += rep_levels[i] == 0;
-        values_to_read += def_levels[i] == this->max_def_level_;
       }
-      levels_position_ = position_end;
       if (records_read == num_records) {
         // Last rep_level reaches the boundary
         ARROW_CHECK_EQ(rep_levels[levels_position_ - 1], 0);
         // We've found the number of records we were looking for. Set
         // at_record_start_ to true and break
         at_record_start_ = true;
-        // Remove last value if we have reaches the end of the record
-        levels_position_ = levels_position_ - 1;
-        values_to_read -= def_levels[levels_position_] == this->max_def_level_;
         break;
       }
+      levels_position_ = position_end;
     }
+    // Scan definition levels to find number of physical values
+    values_to_read += std::count(def_levels + level, def_levels + levels_position_,
+                                 this->max_def_level_);
     *values_seen = values_to_read;
     return records_read;
   }