您好,登录后才能下订单哦!
基于 ElasticSearch-6.1.2
参考官方权威指南 文档元数据
一个文档有三个必须的元数据元素:
_index:表示文档存放在哪个 index 中;
_type:文档表示的对象类型;
_id:文档的唯一标识;
通过使用 index API,使得文档可以被 索引 -- 即存储文档,以及使得文档可以被搜索。
以下为索引一篇blog的例子,其中:index 为 website,类型为 blog,自定义的ID为 123,
PUT /website/blog/123 HTTP/1.1 { "date": "2014/01/01", "text": "Still trying this out...", "title": "My second blog entry"}
ES 的响应体如下:
HTTP/1.1 201 Created Location: /website/blog/123 content-encoding: gzip content-length: 143 content-type: application/json; charset=UTF-8 { "_id": "123", "_index": "website", "_primary_term": 1, "_seq_no": 0, "_shards": { "failed": 0, "successful": 1, "total": 2 }, "_type": "blog", "_version": 1, "result": "created" }
在 ES 中,每个文档都会有个版本号(响应中的 _version 字段),每次修改和删除,_version 都会自增。
采用 POST 提交索引请求:
POST /website/blog/ HTTP/1.1 { "date": "2014/01/01", "text": "Still trying this out...", "title": "My second blog entry" }
如下为 ES 的响应:
HTTP/1.1 201 Created Location: /website/blog/UALcG2EBr-dnzPFB0zH1 content-encoding: gzip content-length: 165 content-type: application/json; charset=UTF-8 { "_id": "UALcG2EBr-dnzPFB0zH1", "_index": "website", "_primary_term": 1, "_seq_no": 0, "_shards": { "failed": 0, "successful": 1, "total": 2 }, "_type": "blog", "_version": 1, "result": "created"}
除了 _id 是 ES 自动生成的之外,其他响应字段都和上面的类似。
自动生成的 ID 是 URL-safe、 基于 Base64 编码且长度为20个字符的 GUID 字符串。 这些 GUID 字符串由可修改的 FlakeID 模式生成,这种模式允许多个节点并行生成唯一 ID ,且互相之间的冲突概率几乎为零。
查询 ID 为 123 的 blog 的请求:
GET /website/blog/123?pretty HTTP/1.1
请求后面的 pretty 参数使得 ES 在输出时调用 prety-print 功能,使得 JSON 响应体更加可读。
ES 响应如下:
HTTP/1.1 200 OK content-encoding: gzip content-length: 173 content-type: application/json; charset=UTF-8 { "_id": "123", "_index": "website", "_source": { "date": "2014/01/01", "text": "Still trying this out...", "title": "My second blog entry" }, "_type": "blog", "_version": 1, "found": true}
响应体中的 {"found": true} 表示文档已经检索到,如果没有指定的文档,则会返回 found = false,如下:
GET /website/blog/124?pretty HTTP/1.1 HTTP/1.1 404 Not Found content-encoding: gzip content-length: 87 content-type: application/json; charset=UTF-8 { "_id": "124", "_index": "website", "_type": "blog", "found": false}
如下只返回 blog 的标题字段,而不是默认的返回所有字段:
GET /website/blog/123?pretty&_source=title HTTP/1.1 HTTP/1.1 200 OK content-encoding: gzip content-length: 136 content-type: application/json; charset=UTF-8 { "_id": "123", "_index": "website", "_source": { "title": "My second blog entry" }, "_type": "blog", "_version": 1, "found": true}
GET /website/blog/123/_source?pretty HTTP/1.1 HTTP/1.1 200 OK content-encoding: gzip content-length: 113 content-type: application/json; charset=UTF-8 { "date": "2014/01/01", "text": "Still trying this out...", "title": "My second blog entry"}
2.3 检查文档是否存在
使用 HEAD 请求,只返回一个 HTTP 请求报文头:
HEAD /website/blog/123 HTTP/1.1 |
如果文档存在,则返回一个 200 OK 的状态码:
HTTP/1.1 200 OK content-length: 186 content-type: application/json; charset=UTF-8 |
如果不存在,则返回一个 404 Not Found 的状态码:
HTTP/1.1 404 Not Found content-length: 61 content-type: application/json; charset=UTF-8 |
3,更新文档
ES 中的文档是 *不可改变* 的,不能修改的,如果需要更新现有的文档,需要 重建索引 或者进行替换。
PUT /website/blog/123 HTTP/1.1 Accept: application/json, */* Accept-Encoding: gzip, deflate Connection: keep-alive Content-Length: 117 Content-Type: application/json Host: localhost:9200 { "date": "2014/01/02", "text": "I am starting to get the hang of this...", "title": "My first blog entry" } |
如下为 ES 的响应体:
HTTP/1.1 200 OK content-encoding: gzip content-length: 143 content-type: application/json; charset=UTF-8 { "_id": "123", "_index": "website", "_primary_term": 2, "_seq_no": 1, "_shards": { "failed": 0, "successful": 1, "total": 2 }, "_type": "blog", "_version": 2, "result": "updated" } |
如上可以看到 _version 字段自增了。在内部,Elasticsearch 已将旧文档标记为已删除,并增加一个全新的文档。 尽管你不能再对旧版本的文档进行访问,但它并不会立即消失。当继续索引更多的数据,Elasticsearch 会在后台清理这些已删除文档。
4,删除文档
使用 DELETE 方法来删除文档。
DELETE /website/blog/123 HTTP/1.1 Accept: */* Accept-Encoding: gzip, deflate Connection: keep-alive Content-Length: 0 Host: localhost:9200 |
ES 返回的响应体如下:
HTTP/1.1 200 OK content-encoding: gzip content-length: 143 content-type: application/json; charset=UTF-8 { "_id": "123", "_index": "website", "_primary_term": 2, "_seq_no": 2, "_shards": { "failed": 0, "successful": 1, "total": 2 }, "_type": "blog", "_version": 3, "result": "deleted" } |
免责声明:本站发布的内容(图片、视频和文字)以原创、转载和分享为主,文章观点不代表本网站立场,如果涉及侵权请联系站长邮箱:is@yisu.com进行举报,并提供相关证据,一经查实,将立刻删除涉嫌侵权内容。