public DualKeyCacheBuilder<FK, SK, V> secondKeySizeComputer(Function<SK, Integer> computer) {
    this.secondKeySizeComputer = computer;
    return this;
  }
Define how to compute the memory usage of a second key in dual key cache.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/analyze/cache/schema/dualkeycache/impl/DualKeyCacheBuilder.java