elasticsearch分词检索的match-query匹配过程分析

1. 模拟字符串数据存储

localhost:9200/yigo-redist.1/_analyze?analyzer=default&text=全能片(前)---TRW-GDB7891AT刹车片自带报警线，无单独报警线号码,卡仕欧,卡仕欧,乘用车,刹车片

•     索引为`yigo-redist.1`
•     使用了索引`yigo-redist.1`中的分词器(`analyzer`) `default`
•     解析的字符串(`text`)为"全能片(前)---TRW-GDB7891AT刹车片自带报警线，无单独报警线号码,卡仕欧,卡仕欧,乘用车,刹车片"

如果结果为:

{
  "tokens" : [ {
    "token" : "全能",
    "start_offset" : 0,
    "end_offset" : 2,
    "type" : "CN_WORD",
    "position" : 1
  }, {
    "token" : "片",
    "start_offset" : 2,
    "end_offset" : 3,
    "type" : "CN_CHAR",
    "position" : 2
  }, {
    "token" : "前",
    "start_offset" : 4,
    "end_offset" : 5,
    "type" : "CN_CHAR",
    "position" : 3
  }, {
    "token" : "trw-gdb7891at",
    "start_offset" : 9,
    "end_offset" : 22,
    "type" : "LETTER",
    "position" : 4
  }, {
    "token" : "刹车片",
    "start_offset" : 22,
    "end_offset" : 25,
    "type" : "CN_WORD",
    "position" : 5
  }, {
    "token" : "自带",
    "start_offset" : 25,
    "end_offset" : 27,
    "type" : "CN_WORD",
    "position" : 6
  }, {
    "token" : "报警",
    "start_offset" : 27,
    "end_offset" : 29,
    "type" : "CN_WORD",
    "position" : 7
  }, {
    "token" : "线",
    "start_offset" : 29,
    "end_offset" : 30,
    "type" : "CN_CHAR",
    "position" : 8
  }, {
    "token" : "无",
    "start_offset" : 31,
    "end_offset" : 32,
    "type" : "CN_WORD",
    "position" : 9
  }, {
    "token" : "单独",
    "start_offset" : 32,
    "end_offset" : 34,
    "type" : "CN_WORD",
    "position" : 10
  }, {
    "token" : "报警",
    "start_offset" : 34,
    "end_offset" : 36,
    "type" : "CN_WORD",
    "position" : 11
  }, {
    "token" : "线",
    "start_offset" : 36,
    "end_offset" : 37,
    "type" : "CN_CHAR",
    "position" : 12
  }, {
    "token" : "号码",
    "start_offset" : 37,
    "end_offset" : 39,
    "type" : "CN_WORD",
    "position" : 13
  }, {
    "token" : "卡",
    "start_offset" : 40,
    "end_offset" : 41,
    "type" : "CN_CHAR",
    "position" : 14
  }, {
    "token" : "仕",
    "start_offset" : 41,
    "end_offset" : 42,
    "type" : "CN_WORD",
    "position" : 15
  }, {
    "token" : "欧",
    "start_offset" : 42,
    "end_offset" : 43,
    "type" : "CN_WORD",
    "position" : 16
  }, {
    "token" : "卡",
    "start_offset" : 44,
    "end_offset" : 45,
    "type" : "CN_CHAR",
    "position" : 17
  }, {
    "token" : "仕",
    "start_offset" : 45,
    "end_offset" : 46,
    "type" : "CN_WORD",
    "position" : 18
  }, {
    "token" : "欧",
    "start_offset" : 46,
    "end_offset" : 47,
    "type" : "CN_WORD",
    "position" : 19
  }, {
    "token" : "乘用车",
    "start_offset" : 48,
    "end_offset" : 51,
    "type" : "CN_WORD",
    "position" : 20
  }, {
    "token" : "刹车片",
    "start_offset" : 52,
    "end_offset" : 55,
    "type" : "CN_WORD",
    "position" : 21
  } ]
}

2. 关键词查询

localhost:9200//yigo-redist.1/_analyze?analyzer=default_search&text=gdb7891

•    索引为`yigo-redist.1`
•    使用了索引`yigo-redist.1`中的分词器(`analyzer`) `default_search`
•    解析的字符串(`text`)为"gdb7891"

返回结果：

{
  "tokens" : [ {
    "token" : "gdb7891",
    "start_offset" : 0,
    "end_offset" : 7,
    "type" : "LETTER",
    "position" : 1
  } ]
}

3. 关键词使用存储的分词器查询

localhost:9200//yigo-redist.1/_analyze?analyzer=default&text=gdb7891

•      索引为`yigo-redist.1`
•      使用了索引`yigo-redist.1`中的分词器(`analyzer`) `default_search`
•      解析的字符串(`text`)为"gdb7891"

返回结果：

{
  "tokens" : [ {
    "token" : "gdb7891",
    "start_offset" : 0,
    "end_offset" : 7,
    "type" : "LETTER",
    "position" : 1
  }, {
    "token" : "",
    "start_offset" : 0,
    "end_offset" : 7,
    "type" : "LETTER",
    "position" : 1
  }, {
    "token" : "gdb7891",
    "start_offset" : 0,
    "end_offset" : 7,
    "type" : "LETTER",
    "position" : 1
  }, {
    "token" : "",
    "start_offset" : 0,
    "end_offset" : 3,
    "type" : "ENGLISH",
    "position" : 2
  }, {
    "token" : "gdb",
    "start_offset" : 0,
    "end_offset" : 3,
    "type" : "ENGLISH",
    "position" : 2
  }, {
    "token" : "gdb",
    "start_offset" : 0,
    "end_offset" : 3,
    "type" : "ENGLISH",
    "position" : 2
  }, {
    "token" : "7891",
    "start_offset" : 3,
    "end_offset" : 7,
    "type" : "ARABIC",
    "position" : 3
  }, {
    "token" : "7891",
    "start_offset" : 3,
    "end_offset" : 7,
    "type" : "ARABIC",
    "position" : 3
  }, {
    "token" : "",
    "start_offset" : 3,
    "end_offset" : 7,
    "type" : "ARABIC",
    "position" : 3
  } ]
}

总结

•     通过步骤1可以看出,存储的数据"全能片(前)---TRW-GDB7891AT刹车片自带报警线，无单独报警线号码,卡仕欧,卡仕欧,乘用车,刹车片",被拆分成了很多词组碎片,然后存储在了索引数据中
•     通过步骤2可以看出,当关键词输入"gdb7891",这个在检索分词器(`default_search`)下,没有拆分,只一个可供查询的碎片就是"gdb7891",但是步骤1,拆分的碎片里不存在"gb7891"的词组碎片,唯一相近的就是"trw-gdb7891at",所以使用普通的match-query是无法匹配步骤1输入的索引数据
•     通过步骤3,可以看出如果使用相同的分词器,"gdb7891"能够拆分成"gdb","7891"等等,通过这2个碎片都能找到步骤1输入的索引数据,但是因为关键词被拆分了,所以会查询到更多的匹配的数据,比如:与"gdb"匹配的,与"7891"匹配的,与"gdb7891"匹配的
•     如果说想通过分词器(`default_search`)检索出步骤1的数据,需要使用wildcard-query,使用"*gdb7891*",就可以匹配

{
      "query": {
            "wildcard" : { "description" : "*gdb7891*" }
      }
}