java - cassandra 中的批量加载器 : String as row keys in cassandra

Question

在 code 的帮助下，我已经使用 key_validation_class=LexicalUUIDType 为新行完成了批量加载。但我已经更改了 key_validation_class=AsciiType 或 key_validation_class=UTF8Type 以使字符串作为行键

  create column family Users1
  with key_validation_class=AsciiType
   and comparator=AsciiType
  AND column_metadata = [ 
  {column_name: timestamp1, validation_class: AsciiType}
  {column_name: symbol, validation_class: AsciiType}
  {column_name: Bid_Price, validation_class:AsciiType}
  {column_name: Ask_Price, validation_class:AsciiType}
  ];

我已经尝试了所有可能的代码更改，以使行键成为字符串类型，但出现错误，甚至没有 usersWriter.newRow 无法写入 sstable

  while ((line = reader.readLine()) != null)
    {
         if (entry.parse(line, lineNumber))
        {   
            //usersWriter.newRow(uuid);
            usersWriter.newRow(String.valueOf(lineNumber));
            usersWriter.addColumn(bytes("symbol"), bytes(entry.symbol), timestamp);
            usersWriter.addColumn(bytes("timestamp1"), bytes(entry.timestamp1), timestamp);
            usersWriter.addColumn(bytes("Bid_Price"), bytes(entry.Bid_Price), timestamp);
            usersWriter.addColumn(bytes("Ask_Price"), bytes(entry.Ask_Price), timestamp);
        }
        lineNumber++;
    }

如预期出现错误，它只使用ByteBuffer

 usersWriter.newRow(String.valueOf(lineNumber));
                       ^
 required: ByteBuffer
 found: String
 reason: actual argument String cannot be converted to ByteBuffer by method invocation  conversion

任何帮助将字符串作为上述列族定义的 sstable 中的行键。谢谢。

Answer 1

来自Using the Cassandra Bulk Loader :

The methods of the simple writer expect ByteBuffers for the row key, column name and column value. Converting data to bytes is your responsibility; this is the raison d’être of the bytes() method.

所以你应该编写如下代码:

usersWriter.newRow(bytes(String.valueOf(lineNumber)));