Elasticsearch之CURL命令的version控制

　　普通关系型数据库使用的是（悲观并发控制（PCC））

　　　　当我们在修改一个数据前先锁定这一行，然后确保只有读取到数据的这个线程可以修改这一行数据

　　

　　ES使用的是（乐观并发控制（OCC））　　

　　　　ES不会阻止某一数据的访问，然而，如果基础数据在我们读取和写入的间隔中发生了变化，更新就会失败，这时候就由程序来决定如何处理这个冲突。它可以重新读取新数据来进行更新，又或者将这一情况直接反馈给用户。

　　ES如何实现版本控制（使用es内部版本号）

　　　　1）首先得到想要修改的文档，获取版本version号

curl -XGET http://master:9200/zhouls/user/2

[hadoop@master elasticsearch-2.4.]$ curl -XGET http://master:9200/zhouls/user/2
{"_index":"zhouls","_type":"user","_id":"","_version":1,"found":true,"_source":{"name" : "john"  , "age" : }}[hadoop@master elasticsearch-2.4.]$
[hadoop@master elasticsearch-2.4.]$
[hadoop@master elasticsearch-2.4.]$ 

　　　　2）在执行更新操作的时候把版本号传过去

curl -XPUT http://master:9200/zhouls/user/2?version=1  -d  '{"name" : "john1" , "age" : 29}'

[hadoop@master elasticsearch-2.4.]$ curl -XPUT http://master:9200/zhouls/user/2?version=1  -d  '{"name" : "john1" , "age" : 29}'
{"_index":"zhouls","_type":"user","_id":"","_version":,"_shards":{"total":,"successful":,"failed":},"created":false}[hadoop@master elasticsearch-2.4.]$ 

curl -XPOST http://master:9200/zhouls/user/2/_update?version=2  -d  '{"doc" :{"age" : 30}}'

[hadoop@master elasticsearch-2.4.]$ curl -XPOST http://master:9200/zhouls/user/2/_update?version=2  -d  '{"doc" :{"age" : 30}}'
{"_index":"zhouls","_type":"user","_id":"","_version":,"_shards":{"total":,"successful":,"failed":}}[hadoop@master elasticsearch-2.4.]$
[hadoop@master elasticsearch-2.4.]$ 

　　

　　3）如果传递的版本号和待更新的文档的版本号不一致，则会更新失败。

　　现在，待更新文档的版本号是3。我分别传1和穿4进入，都会报更新失败。如下

[hadoop@master elasticsearch-2.4.]$ curl -XPOST http://master:9200/zhouls/user/2/_update?version=2  -d  '{"doc" :{"age" : 30}}'
{"_index":"zhouls","_type":"user","_id":"","_version":,"_shards":{"total":,"successful":,"failed":}}[hadoop@master elasticsearch-2.4.]$
[hadoop@master elasticsearch-2.4.]$
[hadoop@master elasticsearch-2.4.]$ curl -XPOST http://master:9200/zhouls/user/2/_update?version=1  -d  '{"doc" :{"age" : 30}}'
{"error":{"root_cause":[{"type":"version_conflict_engine_exception","reason":"[user][2]: version conflict, current [3], provided [1]","index":"zhouls","shard":""}],"type":"version_conflict_engine_exception","reason":"[user][2]: version conflict, current [3], provided [1]","index":"zhouls","shard":""},"status":}[hadoop@master elasticsearch-2.4.]$
[hadoop@master elasticsearch-2.4.]$
[hadoop@master elasticsearch-2.4.]$ curl -XPOST http://master:9200/zhouls/user/2/_update?version=4  -d  '{"doc" :{"age" : 30}}'
{"error":{"root_cause":[{"type":"version_conflict_engine_exception","reason":"[user][2]: version conflict, current [3], provided [4]","index":"zhouls","shard":""}],"type":"version_conflict_engine_exception","reason":"[user][2]: version conflict, current [3], provided [4]","index":"zhouls","shard":""},"status":}[hadoop@master elasticsearch-2.4.]$
[hadoop@master elasticsearch-2.4.]$
[hadoop@master elasticsearch-2.4.]$ 

　　更多，请见

Elasticsearch笔记三之版本控制和插件