term 和 match 总结
在实际的项目查询中，term和match 是最常用的两个查询，而经常搞不清两者有什么区别，趁机总结有空总结下。
term用法
先看看term的定义，term是代表完全匹配，也就是精确查询，搜索前不会再对搜索词进行分词拆解。
这里通过例子来说明，先存放一些数据：
{
"title": "love China",
"content": "people very love China",
"tags": ["China", "love"]
}
{
"title": "love HuBei",
"content": "people very love HuBei",
"tags": ["HuBei", "love"]
}
来使用term 查询下：
{
"query": {
"term": {
"title": "love"
}
}
}
结果是，上面的两条数据都能查询到：
{
"took": 1,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"skipped": 0,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 0.6931472,
"hits": [
{
"_index": "test",
"_type": "doc",
"_id": "8",
"_score": 0.6931472,
"_source": {
"title": "love HuBei",
"content": "people very love HuBei",
"tags": ["HuBei","love"]
}
},
{
"_index": "test",
"_type": "doc",
"_id": "7",
"_score": 0.6931472,
"_source": {
"title": "love China",
"content": "people very love China",
"tags": ["China","love"]
}
}
]
}
}
发现，title里有关love的关键字都查出来了，但是我只想精确匹配 love China这个，按照下面的写法看看能不能查出来：
{
"query": {
"term": {
"title": "love China"
}
}
}
执行发现无数据，从概念上看，term属于精确匹配，只能查单个词。我想用term匹配多个词怎么做？可以使用terms来：
{
"query": {
"terms": {
"title": ["love", "China"]
}
}
}
查询结果为：
{
"took": 1,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"skipped": 0,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 0.6931472,
"hits": [
{
"_index": "test",
"_type": "doc",
"_id": "8",
"_score": 0.6931472,
"_source": {
"title": "love HuBei",
"content": "people very love HuBei",
"tags": ["HuBei","love"]
}
},
{
"_index": "test",
"_type": "doc",
"_id": "7",
"_score": 0.6931472,
"_source": {
"title": "love China",
"content": "people very love China",
"tags": ["China","love"]
}
}
]
}
}
发现全部查询出来，为什么？因为terms里的[ ] 多个是或者的关系，只要满足其中一个词就可以。想要通知满足两个词的话，就得使用bool的must来做，如下：
{
"query": {
"bool": {
"must": [
{
"term": {
"title": "love"
}
},
{
"term": {
"title": "china"
}
}
]
}
}
}
可以看到，我们上面使用china是小写的。当使用的是大写的China 我们进行搜索的时候，发现搜不到任何信息。这是为什么了？title这个词在进行存储的时候，进行了分词处理。我们这里使用的是默认的分词处理器进行了分词处理。我们可以看看如何进行分词处理的？
分词处理器
GET test/_analyze
{
"text" : "love China"
}
结果为：
{
"tokens": [
{
"token": "love",
"start_offset": 0,
"end_offset": 4,
"type": "<ALPHANUM>",
"position": 0
},
{
"token": "china",
"start_offset": 5,
"end_offset": 10,
"type": "<ALPHANUM>",
"position": 1
}
]
}
分析出来的为love和china的两个词。而term只能完完整整的匹配上面的词，不做任何改变的匹配。所以，我们使用China这样的方式进行的查询的时候，就会失败。稍后会有一节专门讲解分词器。
match 用法
先用 love China来匹配。
GET test/doc/_search
{
"query": {
"match": {
"title": "love China"
}
}
}
结果是：
{
"took": 1,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"skipped": 0,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 1.3862944,
"hits": [
{
"_index": "test",
"_type": "doc",
"_id": "7",
"_score": 1.3862944,
"_source": {
"title": "love China",
"content": "people very love China",
"tags": [
"China",
"love"
]
}
},
{
"_index": "test",
"_type": "doc",
"_id": "8",
"_score": 0.6931472,
"_source": {
"title": "love HuBei",
"content": "people very love HuBei",
"tags": [
"HuBei",
"love"
]
}
}
]
}
}
发现两个都查出来了，为什么？因为match进行搜索的时候，会先进行分词拆分，拆完后，再来匹配，上面两个内容，他们title的词条为： love china hubei ，我们搜索的为love China 我们进行分词处理得到为love china ，并且属于或的关系，只要任何一个词条在里面就能匹配到。如果想 love 和 China 同时匹配到的话，怎么做？使用 match_phrase
match_phrase 用法
match_phrase 称为短语搜索，要求所有的分词必须同时出现在文档中，同时位置必须紧邻一致。
GET test/doc/_search
{
"query": {
"match_phrase": {
"title": "love china"
}
}
}
结果为：
{
"took": 5,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"skipped": 0,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 1.3862944,
"hits": [
{
"_index": "test",
"_type": "doc",
"_id": "7",
"_score": 1.3862944,
"_source": {
"title": "love China",
"content": "people very love China",
"tags": [
"China",
"love"
]
}
}
]
}
}
这次好像符合我们的需求了，结果只出现了一条记录。
