Cassandra没有插入 null 当您省略特定列的数据时。这个 null 当您读取数据并且数据丢失时返回。最好使用 sstabledump . 例如，对于我的数据：

cqlsh:test> select * from test.st1;

 id | c1   | s1 | v1
----+------+----+------
 10 | null | 10 | null
  1 |    1 |  2 |    1
  1 |    2 |  2 |    1
  2 |   10 |  3 | null

(4 rows)

对于最后一行，我可以看到我没有实际的数据，因为 cells 为空：

{
    "partition" : {
      "key" : [ "2" ],
      "position" : 97
    },
    "rows" : [
      {
        "type" : "static_block",
        "position" : 144,
        "cells" : [
          { "name" : "s1", "value" : 3, "tstamp" : "2019-04-12T14:33:47.198445Z" }
        ]
      },
      {
        "type" : "row",
        "position" : 144,
        "clustering" : [ 10 ],
        "liveness_info" : { "tstamp" : "2019-04-29T12:49:31.450239Z" },
        "cells" : [ ]
      }
    ]
  }

但如果我插入 null 明确地：

cqlsh:test> insert into test.st1(id, s1, c1, v1) values (3, 10, 3, null);

然后我将在数据文件中看到它作为 cells :

{
    "partition" : {
      "key" : [ "3" ],
      "position" : 0
    },
    "rows" : [
      {
        "type" : "static_block",
        "position" : 39,
        "cells" : [
          { "name" : "s1", "value" : 10, "tstamp" : "2020-07-09T09:19:39.751467Z" }
        ]
      },
      {
        "type" : "row",
        "position" : 39,
        "clustering" : [ 3 ],
        "liveness_info" : { "tstamp" : "2020-07-09T09:19:39.751467Z" },
        "cells" : [
          { "name" : "v1", "deletion_info" : { "local_delete_time" : "2020-07-09T09:19:39Z" }
          }
        ]
      }
    ]
  }