private void removeTableFromPreUpdateMap(final String database, final String tableName) {
    preUpdateTableMap.compute(
        database,
        (k, v) -> {
          if (v == null) {
            throw new IllegalStateException();
          }
          v.get(tableName).setLeft(null);
          return v;
        });
  }
It contains all tables' latest column schema
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/table/DataNodeTableCache.java