内容简介：下面以IT技术论坛为案例背景输出：注意：初步来讲，先搞4个字段，因为整个es是支持json document格式的，所以说扩展性和灵活性非常之好。如果后续随着业务需求的增加，要在document中增加更多的field，那么我们可以很方便的随时添加field。但是如果是在关系型数据库中，比如mysql，我们建立了一个表，现在要给表中新增一些column，那么就很坑爹了，必须用复杂的修改表结构的语法去执行。而且可能对系统代码还有一定的影响。
下面以IT技术论坛为案例背景
1、根据用户ID、是否隐藏、帖子ID、发帖日期来搜索帖子
（1）插入一些测试帖子的数据
POST /forum/_bulk {"index": {"_id": 1}} { "articleID" : "XHDK-A-1293-#fJ3", "userID" : 1, "hidden": false, "postDate": "2017-01-01" } { "index": { "_id": 2 }} { "articleID" : "KDKE-B-9947-#kL5", "userID" : 1, "hidden": false, "postDate": "2017-01-02" } {"index": {"_id": 3}} { "articleID" : "JODL-X-1937-#pV7", "userID" : 2, "hidden": false, "postDate": "2017-01-01" } { "index": { "_id": 4 }} { "articleID" : "QQPX-R-3956-#aD8", "userID" : 2, "hidden": true, "postDate": "2017-01-02" }
输出：
{ "took" : 269, "errors" : false, "items" : [ { "index" : { "_index" : "forum", "_type" : "_doc", "_id" : "1", "_version" : 1, "result" : "created", "_shards" : { "total" : 2, "successful" : 1, "failed" : 0 }, "_seq_no" : 0, "_primary_term" : 1, "status" : 201 } }, { "index" : { "_index" : "forum", "_type" : "_doc", "_id" : "2", "_version" : 1, "result" : "created", "_shards" : { "total" : 2, "successful" : 1, "failed" : 0 }, "_seq_no" : 1, "_primary_term" : 1, "status" : 201 } }, { "index" : { "_index" : "forum", "_type" : "_doc", "_id" : "3", "_version" : 1, "result" : "created", "_shards" : { "total" : 2, "successful" : 1, "failed" : 0 }, "_seq_no" : 2, "_primary_term" : 1, "status" : 201 } }, { "index" : { "_index" : "forum", "_type" : "_doc", "_id" : "4", "_version" : 1, "result" : "created", "_shards" : { "total" : 2, "successful" : 1, "failed" : 0 }, "_seq_no" : 3, "_primary_term" : 1, "status" : 201 } } ] }
注意：初步来讲，先搞4个字段，因为整个es是支持json document格式的，所以说扩展性和灵活性非常之好。如果后续随着业务需求的增加，要在document中增加更多的field，那么我们可以很方便的随时添加field。但是如果是在关系型数据库中，比如mysql，我们建立了一个表，现在要给表中新增一些column，那么就很坑爹了，必须用复杂的修改表结构的语法去执行。而且可能对系统代码还有一定的影响。
（2）根据用户ID搜索帖子
GET /forum/_search { "query": { "constant_score": { "filter": { "term": { "userID": 1 } } } } }
输出:
{ "took" : 6, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 2, "relation" : "eq" }, "max_score" : 1.0, "hits" : [ { "_index" : "forum", "_type" : "_doc", "_id" : "1", "_score" : 1.0, "_source" : { "articleID" : "XHDK-A-1293-#fJ3", "userID" : 1, "hidden" : false, "postDate" : "2017-01-01" } }, { "_index" : "forum", "_type" : "_doc", "_id" : "2", "_score" : 1.0, "_source" : { "articleID" : "KDKE-B-9947-#kL5", "userID" : 1, "hidden" : false, "postDate" : "2017-01-02" } } ] } }
term filter/query : 对搜索文本不分词，直接拿去倒排索引中去匹配，你输入的是什么，就去匹配什么
（3）搜索没有隐藏的帖子
GET /forum/_search { "query": { "constant_score": { "filter": { "term": { "hidden": false } } } } }
输出：
{ "took" : 2, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 3, "relation" : "eq" }, "max_score" : 1.0, "hits" : [ { "_index" : "forum", "_type" : "_doc", "_id" : "1", "_score" : 1.0, "_source" : { "articleID" : "XHDK-A-1293-#fJ3", "userID" : 1, "hidden" : false, "postDate" : "2017-01-01" } }, { "_index" : "forum", "_type" : "_doc", "_id" : "2", "_score" : 1.0, "_source" : { "articleID" : "KDKE-B-9947-#kL5", "userID" : 1, "hidden" : false, "postDate" : "2017-01-02" } }, { "_index" : "forum", "_type" : "_doc", "_id" : "3", "_score" : 1.0, "_source" : { "articleID" : "JODL-X-1937-#pV7", "userID" : 2, "hidden" : false, "postDate" : "2017-01-01" } } ] } }
（4）根据发帖日期搜索帖子
GET /forum/_search { "query": { "constant_score": { "filter": { "term": { "postDate": "2017-01-01" } } } } }
输出:
{ "took" : 5, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 2, "relation" : "eq" }, "max_score" : 1.0, "hits" : [ { "_index" : "forum", "_type" : "_doc", "_id" : "1", "_score" : 1.0, "_source" : { "articleID" : "XHDK-A-1293-#fJ3", "userID" : 1, "hidden" : false, "postDate" : "2017-01-01" } }, { "_index" : "forum", "_type" : "_doc", "_id" : "3", "_score" : 1.0, "_source" : { "articleID" : "JODL-X-1937-#pV7", "userID" : 2, "hidden" : false, "postDate" : "2017-01-01" } } ] } }
（5）根据帖子ID搜索帖子
GET /forum/_search { "query": { "constant_score": { "filter": { "term": { "articleID.keyword": "XHDK-A-1293-#fJ3" } } } } }
输出:
{ "took" : 1, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 1, "relation" : "eq" }, "max_score" : 1.0, "hits" : [ { "_index" : "forum", "_type" : "_doc", "_id" : "1", "_score" : 1.0, "_source" : { "articleID" : "XHDK-A-1293-#fJ3", "userID" : 1, "hidden" : false, "postDate" : "2017-01-01" } } ] } }
如果不使用keyword
GET /forum/_search { "query": { "constant_score": { "filter": { "term": { "articleID": "XHDK-A-1293-#fJ3" } } } } }
输出：
{ "took" : 0, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 0, "relation" : "eq" }, "max_score" : null, "hits" : [ ] } }
articleID.keyword是ES最新版本内置建立的field，就是不分词的，所以一个articleID过来的时候，会建立两次索引，一次是自己本省，是要分词的，分词后放入倒排索引，另外一次是基于articleID.keyword不分词的，保留最多256个字符，直接一个字符串放入倒排索引中。在实际使用的时候如果有必要可以手动指定type=keyword，那样就可以避免自动创建默认保留256个字符
（6）查看分词
GET /forum/_analyze { "field": "articleID", "text": ["XHDK-A-1293-#fJ3"] }
输出：
{ "tokens" : [ { "token" : "xhdk", "start_offset" : 0, "end_offset" : 4, "type" : "<ALPHANUM>", "position" : 0 }, { "token" : "a", "start_offset" : 5, "end_offset" : 6, "type" : "<ALPHANUM>", "position" : 1 }, { "token" : "1293", "start_offset" : 7, "end_offset" : 11, "type" : "<NUM>", "position" : 2 }, { "token" : "fj3", "start_offset" : 13, "end_offset" : 16, "type" : "<ALPHANUM>", "position" : 3 } ] }
默认的分词的text类型的field，建立倒排索引的时候，就会对所有的articleID分词，分词之后，原本的articleID就没有了，之后分词后的各个word存在于倒排索引中。
（7）重建索引
DELETE /forum PUT /forum { "mappings": { "properties": { "articleID": { "type": "keyword" } } } } POST /forum/_bulk { "index": { "_id": 1 }} { "articleID" : "XHDK-A-1293-#fJ3", "userID" : 1, "hidden": false, "postDate": "2017-01-01" } { "index": { "_id": 2 }} { "articleID" : "KDKE-B-9947-#kL5", "userID" : 1, "hidden": false, "postDate": "2017-01-02" } { "index": { "_id": 3 }} { "articleID" : "JODL-X-1937-#pV7", "userID" : 2, "hidden": false, "postDate": "2017-01-01" } { "index": { "_id": 4 }} { "articleID" : "QQPX-R-3956-#aD8", "userID" : 2, "hidden": true, "postDate": "2017-01-02" }
（8）重新根据帖子ID和发帖日期进行搜索
GET /forum/_search { "query": { "constant_score": { "filter": { "term": { "articleID": "XHDK-A-1293-#fJ3" } } } } }
输出：
{ "took" : 1, "timed_out" : false, "_shards" : { "total" : 1, "successful" : 1, "skipped" : 0, "failed" : 0 }, "hits" : { "total" : { "value" : 1, "relation" : "eq" }, "max_score" : 1.0, "hits" : [ { "_index" : "forum", "_type" : "_doc", "_id" : "1", "_score" : 1.0, "_source" : { "articleID" : "XHDK-A-1293-#fJ3", "userID" : 1, "hidden" : false, "postDate" : "2017-01-01" } } ] } }
2、总结
（1）term filter:根据exact value进行搜索，像数字、boolean、date是天然支持
（2）text需要建立索引时指定为not_analyzed,才能使用term
（3）相当于 SQL 中的单个where条件
select * from forum where articleID = 'XHDK-A-1293-#fJ3'
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