17、分布式文档系统_动手实战演练Elasticsearch基于

1、先构造一条数据出来

PUT /test_index/test_type/7
{
  "test_field":"test test"
}
-------------------------------结果-------------------------------
{
  "_index": "test_index",
  "_type": "test_type",
  "_id": "7",
  "_version": 1,
  "result": "created",
  "_shards": {
    "total": 2,
    "successful": 1,
    "failed": 0
  },
  "created": true
}

2、模拟两个客户端，都获取到了同一条数据

获取数据：GET /test_index/test_type/7
-------------------------------结果-------------------------------
{
  "_index": "test_index",
  "_type": "test_type",
  "_id": "7",
  "_version": 1,
  "found": true,
  "_source": {
    "test_field": "test test"
  }
}

3、其中一个客户端，先更新了一下这个数据，同时带上数据的版本号，确保说，es中的数据的版本号，跟客户端中的数据的版本号是相同的，才能修改

首先更新一个客户端，版本号为1
PUT test_index/test_type/7?version=1
{
  "test_field":"test client 1"
}
-------------------------------结果-------------------------------
更新成功，version变为2
{
  "_index": "test_index",
  "_type": "test_type",
  "_id": "7",
  "_version": 2,
  "result": "updated",
  "_shards": {
    "total": 2,
    "successful": 1,
    "failed": 0
  },
  "created": false
}

4、另外一个客户端，尝试基于version=1的数据去进行修改，同样带上version版本号，进行乐观锁的并发控制

模拟两个客户端同一时间更新
PUT test_index/test_type/7?version=1
{
  "test_field":"test client 2"
}
-------------------------------结果-------------------------------
{
  "error": {
    "root_cause": [
      {
        "type": "version_conflict_engine_exception",
        "reason": "[test_type][7]: version conflict, current version [2] is different than the one provided [1]",
        "index_uuid": "8GnE3L60TnWxjSrPQ7Xa2A",
        "shard": "0",
        "index": "test_index"
      }
    ],
    "type": "version_conflict_engine_exception",
    "reason": "[test_type][7]: version conflict, current version [2] is different than the one provided [1]",
    "index_uuid": "8GnE3L60TnWxjSrPQ7Xa2A",
    "shard": "0",
    "index": "test_index"
  },
  "status": 409
}

5、在乐观锁成功阻止并发问题之后，尝试正确的完成更新

1.首先重新获取数据
GET /test_index/test_type/7
-------------------------------结果-------------------------------
{
  "_index": "test_index",
  "_type": "test_type",
  "_id": "7",
  "_version": 2,
  "found": true,
  "_source": {
    "test_field": "test client 1"
  }
}
2.基于最新的数据和版本号，去进行修改，修改后，带上最新的版本号，可能这个步骤会需要反复执行好几次，才能成功，特别是在多线程并发更新同一条数据很频繁的情况下
PUT test_index/test_type/7?version=2
{
  "test_field":"test client 2"
}
-------------------------------结果-------------------------------
{
  "_index": "test_index",
  "_type": "test_type",
  "_id": "7",
  "_version": 3,
  "result": "updated",
  "_shards": {
    "total": 2,
    "successful": 1,
    "failed": 0
  },
  "created": false
}
更新成功，版本号自动更新为version = 3