Cell tombstones

CassandraのCell tombstonesについて

Cell tombstoneは、特定のセルの削除で生成するtombstone

before

cqlsh:sitest01>  select * from test_tomb where pkey1 = 'rei' and pkey2 =1;

 pkey1 | pkey2 | skey1 | v1
-------+-------+-------+---------------------
   rei |     1 |     1 |              Bombay
   rei |     1 |     2 | Brazilian Shorthair

(2 rows)

  {
    "partition" : {
      "key" : [ "rei", "1" ],
      "position" : 290
    },
    "rows" : [
      {
        "type" : "row",
        "position" : 336,
        "clustering" : [ 1 ],
        "liveness_info" : { "tstamp" : "2019-12-15T08:45:48.827508Z" },
        "cells" : [
          { "name" : "v1", "value" : "Bombay" }
        ]
      },
      {
        "type" : "row",
        "position" : 336,
        "clustering" : [ 2 ],
        "liveness_info" : { "tstamp" : "2019-12-15T08:45:48.833270Z" },
        "cells" : [
          { "name" : "v1", "value" : "Brazilian Shorthair" }
        ]
      }
    ]
  }

delete

cqlsh:sitest01> delete v1 from test_tomb where pkey1 = 'rei' and pkey2 =1 and skey1 = 1;

after

cqlsh:sitest01>  select * from test_tomb where pkey1 = 'rei' and pkey2 =1;

 pkey1 | pkey2 | skey1 | v1
-------+-------+-------+---------------------
   rei |     1 |     1 |                null
   rei |     1 |     2 | Brazilian Shorthair

(2 rows)

  {
    "partition" : {
      "key" : [ "rei", "1" ],
      "position" : 290
    },
    "rows" : [
      {
        "type" : "row",
        "position" : 335,
        "clustering" : [ 1 ],
        "liveness_info" : { "tstamp" : "2019-12-15T08:45:48.827508Z" },
        "cells" : [
          { "name" : "v1", "deletion_info" : { "local_delete_time" : "2019-12-15T09:04:53Z" },
            "tstamp" : "2019-12-15T09:04:53.756348Z"
          }
        ]
      },
      {
        "type" : "row",
        "position" : 335,
        "clustering" : [ 2 ],
        "liveness_info" : { "tstamp" : "2019-12-15T08:45:48.833270Z" },
        "cells" : [
          { "name" : "v1", "value" : "Brazilian Shorthair" }
        ]
      }
    ]
  }


Estimated tombstone drop times:
1576400700:         1