1、bulk語法

POST /_bulk
{ "delete": { "_index": "test_index", "_type": "test_type", "_id": "3" }} 
{ "create": { "_index": "test_index", "_type": "test_type", "_id": "12" }}
{ "test_field":    "test12" }
{ "index":  { "_index": "test_index", "_type": "test_type", "_id": "2" }}
{ "test_field":    "replaced test2" }
{ "update": { "_index": "test_index", "_type": "test_type", "_id": "1", "_retry_on_conflict" : 3} }
{ "doc" : {"test_field2" : "bulk test1"} }

每一個操作要兩個json串，語法如下：

{"action": {"metadata"}}
{"data"}

舉例，比如你現在要建立一個文件，放bulk裡面，看起來會是這樣子的：

{"index": {"_index": "test_index", "_type", "test_type", "_id": "1"}}
{"test_field1": "test1", "test_field2": "test2"}

有哪些型別的操作可以執行呢？
（1）delete：刪除一個文件，只要1個json串就可以了
（2）create：PUT /index/type/id/_create，強制建立
（3）index：普通的put操作，可以是建立文件，也可以是全量替換文件
（4）update：執行的partial update操作

bulk api對json的語法，有嚴格的要求，每個json串不能換行，只能放一行，同時一個json串和一個json串之間，必須有一個換行

{
  "error": {
    "root_cause": [
      {
        "type": "json_e_o_f_exception",
        "reason": "Unexpected end-of-input: expected close marker for Object (start marker at [Source: 
 
[email protected]; line: 1, column: 1])\n at [Source: org.elasticsearch.transport.netty4.By[email protected]; line: 1, column: 3]"
      }
    ],
    "type": "json_e_o_f_exception",
    "reason": "Unexpected end-of-input: expected close marker for Object (start marker at [Source: [email protected]
 
; line: 1, column: 1])\n at [Source: [email protected]; line: 1, column: 3]"
  },
  "status": 500
}

{
  "took": 41,
  "errors": true,
  "items": [
    {
      "delete": {
        "found": true,
        "_index": "test_index",
        "_type": "test_type",
        "_id": "10",
        "_version": 3,
        "result": "deleted",
        "_shards": {
          "total": 2,
          "successful": 1,
          "failed": 0
        },
        "status": 200
      }
    },
    {
      "create": {
        "_index": "test_index",
        "_type": "test_type",
        "_id": "3",
        "_version": 1,
        "result": "created",
        "_shards": {
          "total": 2,
          "successful": 1,
          "failed": 0
        },
        "created": true,
        "status": 201
      }
    },
    {
      "create": {
        "_index": "test_index",
        "_type": "test_type",
        "_id": "2",
        "status": 409,
        "error": {
          "type": "version_conflict_engine_exception",
          "reason": "[test_type][2]: version conflict, document already exists (current version [1])",
          "index_uuid": "6m0G7yx7R1KECWWGnfH1sw",
          "shard": "2",
          "index": "test_index"
        }
      }
    },
    {
      "index": {
        "_index": "test_index",
        "_type": "test_type",
        "_id": "4",
        "_version": 1,
        "result": "created",
        "_shards": {
          "total": 2,
          "successful": 1,
          "failed": 0
        },
        "created": true,
        "status": 201
      }
    },
    {
      "index": {
        "_index": "test_index",
        "_type": "test_type",
        "_id": "2",
        "_version": 2,
        "result": "updated",
        "_shards": {
          "total": 2,
          "successful": 1,
          "failed": 0
        },
        "created": false,
        "status": 200
      }
    },
    {
      "update": {
        "_index": "test_index",
        "_type": "test_type",
        "_id": "1",
        "_version": 3,
        "result": "updated",
        "_shards": {
          "total": 2,
          "successful": 1,
          "failed": 0
        },
        "status": 200
      }
    }
  ]
}

bulk操作中，任意一個操作失敗，是不會影響其他的操作的，但是在返回結果裡，會告訴你異常日誌

POST /test_index/_bulk
{ "delete": { "_type": "test_type", "_id": "3" }} 
{ "create": { "_type": "test_type", "_id": "12" }}
{ "test_field":    "test12" }
{ "index":  { "_type": "test_type" }}
{ "test_field":    "auto-generate id test" }
{ "index":  { "_type": "test_type", "_id": "2" }}
{ "test_field":    "replaced test2" }
{ "update": { "_type": "test_type", "_id": "1", "_retry_on_conflict" : 3} }
{ "doc" : {"test_field2" : "bulk test1"} }

POST /test_index/test_type/_bulk
{ "delete": { "_id": "3" }} 
{ "create": { "_id": "12" }}
{ "test_field":    "test12" }
{ "index":  { }}
{ "test_field":    "auto-generate id test" }
{ "index":  { "_id": "2" }}
{ "test_field":    "replaced test2" }
{ "update": { "_id": "1", "_retry_on_conflict" : 3} }
{ "doc" : {"test_field2" : "bulk test1"} }

2、bulk size最佳大小

bulk request會載入到記憶體裡，如果太大的話，效能反而會下降，因此需要反覆嘗試一個最佳的bulk size。一般從1000~5000條資料開始，嘗試逐漸增加。另外，如果看大小的話，最好是在5~15MB之間。