private void allocateNewSegment() {
    long[] newSegment = new long[SEGMENT_SIZE];
    if (initialValue != 0) {
      Arrays.fill(newSegment, initialValue);
    }
    array[segments] = newSegment;
    capacity += SEGMENT_SIZE;
    segments++;
  }
Fills the entire big array with the specified value.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/source/relational/aggregation/grouped/array/LongBigArray.java