一、exists查询简介
elastic search提供了exists查询，用以返回字段存在值的记录，默认情况下只有字段的值为null或者[]的时候，elasticsearch才会认为字段不存在；
exists查询的形式如下，其中field用于指定要查询的字段名字；
{
"query": {
"exists": {
"field": "user"
}
}
}
二、测试数据准备
我们尽量模拟document中字段可能出现的各种形式，以便可以全面的测试以下exists查询；
PUT exists_test/_doc/1/
{
"name":"sam",
"age":30,
"man": true,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/2/
{
"name":"",
"age":30,
"man": true,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/3/
{
"name":null,
"age":30,
"man": true,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/4/
{
"age":30,
"man": true,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/5/
{
"name":"sam",
"age":null,
"man": true,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/6/
{
"name":"sam",
"man": true,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/7/
{
"name":"sam",
"age":30,
"man": null,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/8/
{
"name":"sam",
"age":30,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/9/
{
"name":"sam",
"age":30,
"man": true,
"child":["", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/10/
{
"name":"sam",
"age":30,
"man": true,
"child":["", ""],
"address":{"country":"US"}
}
PUT exists_test/_doc/11/
{
"name":"sam",
"age":30,
"man": true,
"child":[null, "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/12/
{
"name":"sam",
"age":30,
"man": true,
"child":[null, null],
"address":{"country":"US"}
}
PUT exists_test/_doc/13/
{
"name":"sam",
"age":30,
"man": true,
"child":[],
"address":{"country":"US"}
}
PUT exists_test/_doc/14/
{
"name":"sam",
"age":30,
"man": true,
"child":null,
"address":{"country":"US"}
}
PUT exists_test/_doc/15/
{
"name":"sam",
"age":30,
"man": true,
"address":{"country":"US"}
}
PUT exists_test/_doc/16/
{
"name":"sam",
"age":30,
"man": true,
"child":["jhon", "lily"],
"address":{}
}
PUT exists_test/_doc/17/
{
"name":"sam",
"age":30,
"man": true,
"child":["jhon", "lily"],
"address":null
}
PUT exists_test/_doc/18/
{
"name":"sam",
"age":30,
"man": true,
"child":["jhon", "lily"]
}
PUT exists_test/_doc/19/
{
"name":"sam",
"age":0,
"man": true,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/20/
{
"name":"-",
"age":30,
"man": true,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
PUT exists_test/_doc/21/
{
"name":";",
"age":30,
"man": true,
"child":["jhon", "lily"],
"address":{"country":"US"}
}
三、exists查询测试
对于字符串类型字段，当字段没有出现、字段值为null的情况下，则该字段不存在；字段值为空则计算为字段存在；
POST exists_test/_doc/_search/
{
"query":{
"bool":{
"must_not":{
"exists":{
"field":"name"
}
}
}
}
}
{
"took":3,
"timed_out":false,
"_shards":{
"total":5,
"successful":5,
"skipped":0,
"failed":0
},
"hits":{
"total":2,
"max_score":1,
"hits":[
{
"_index":"exists_test",
"_type":"_doc",
"_id":"4",
"_score":1,
"_source":{
"age":30,
"man":true,
"child":[
"jhon",
"lily"
],
"address":{
"country":"US"
}
}
},
{
"_index":"exists_test",
"_type":"_doc",
"_id":"3",
"_score":1,
"_source":{
"name":null,
"age":30,
"man":true,
"child":[
"jhon",
"lily"
],
"address":{
"country":"US"
}
}
}
]
}
}
对于数字类型字段，当字段没有出现、字段值为null的情况下，则该字段不存在；
POST exists_test/_doc/_search/
{
"query":{
"bool":{
"must_not":{
"exists":{
"field":"age"
}
}
}
}
}
{
"took":1,
"timed_out":false,
"_shards":{
"total":5,
"successful":5,
"skipped":0,
"failed":0
},
"hits":{
"total":2,
"max_score":1,
"hits":[
{
"_index":"exists_test",
"_type":"_doc",
"_id":"5",
"_score":1,
"_source":{
"name":"sam",
"age":null,
"man":true,
"child":[
"jhon",
"lily"
],
"address":{
"country":"US"
}
}
},
{
"_index":"exists_test",
"_type":"_doc",
"_id":"6",
"_score":1,
"_source":{
"name":"sam",
"man":true,
"child":[
"jhon",
"lily"
],
"address":{
"country":"US"
}
}
}
]
}
}
对于布尔类型字段，当字段没有出现、字段值为null的情况下，则该字段不存在；
POST exists_test/_doc/_search/
{
"query":{
"bool":{
"must_not":{
"exists":{
"field":"man"
}
}
}
}
}
{
"took":1,
"timed_out":false,
"_shards":{
"total":5,
"successful":5,
"skipped":0,
"failed":0
},
"hits":{
"total":2,
"max_score":1,
"hits":[
{
"_index":"exists_test",
"_type":"_doc",
"_id":"8",
"_score":1,
"_source":{
"name":"sam",
"age":30,
"child":[
"jhon",
"lily"
],
"address":{
"country":"US"
}
}
},
{
"_index":"exists_test",
"_type":"_doc",
"_id":"7",
"_score":1,
"_source":{
"name":"sam",
"age":30,
"man":null,
"child":[
"jhon",
"lily"
],
"address":{
"country":"US"
}
}
}
]
}
}
对于数组类型字段，只要字段没有出现、字段值为null、字段值为空数组、字段值数组的所有元素都为null，则该字段不存在；
POST exists_test/_doc/_search/
{
"query":{
"bool":{
"must_not":{
"exists":{
"field":"child"
}
}
}
}
}
{
"took":1,
"timed_out":false,
"_shards":{
"total":5,
"successful":5,
"skipped":,
"failed":
},
"hits":{
"total":4,
"max_score":1,
"hits":[
{
"_index":"exists_test",
"_type":"_doc",
"_id":"14",
"_score":1,
"_source":{
"name":"sam",
"age":30,
"man":true,
"child":null,
"address":{
"country":"US"
}
}
},
{
"_index":"exists_test",
"_type":"_doc",
"_id":"12",
"_score":1,
"_source":{
"name":"sam",
"age":30,
"man":true,
"child":[
null,
null
],
"address":{
"country":"US"
}
}
},
{
"_index":"exists_test",
"_type":"_doc",
"_id":"15",
"_score":1,
"_source":{
"name":"sam",
"age":30,
"man":true,
"address":{
"country":"US"
}
}
},
{
"_index":"exists_test",
"_type":"_doc",
"_id":"13",
"_score":1,
"_source":{
"name":"sam",
"age":30,
"man":true,
"child":[
],
"address":{
"country":"US"
}
}
}
]
}
}
对于对象字段，只要字段没有出现、字段值是空对象、字段值为null，则该字段不存在；
POST exists_test/_doc/_search/
{
"query":{
"bool":{
"must_not":{
"exists":{
"field":"address"
}
}
}
}
}
{
"took":40,
"timed_out":false,
"_shards":{
"total":5,
"successful":5,
"skipped":0,
"failed":0
},
"hits":{
"total":3,
"max_score":1,
"hits":[
{
"_index":"exists_test",
"_type":"_doc",
"_id":"16",
"_score":1,
"_source":{
"name":"sam",
"age":30,
"man":true,
"child":[
"jhon",
"lily"
],
"address":{
}
}
},
{
"_index":"exists_test",
"_type":"_doc",
"_id":"18",
"_score":1,
"_source":{
"name":"sam",
"age":30,
"man":true,
"child":[
"jhon",
"lily"
]
}
},
{
"_index":"exists_test",
"_type":"_doc",
"_id":"17",
"_score":1,
"_source":{
"name":"sam",
"age":30,
"man":true,
"child":[
"jhon",
"lily"
],
"address":null
}
}
]
}
}
四、测试总结
elasticsearch对于各种类型字段判断字段是否存在的判断条件如下
1.对于字符串类型字段，当字段没有出现、字段值为null的情况下，则该字段不存在；字段值为空则计算为字段存在；
2.对于数字类型字段，当字段没有出现、字段值为null的情况下，则该字段不存在；
3.对于布尔类型字段，当字段没有出现、字段值为null的情况下，则该字段不存在；
4.对于数组类型字段，只要字段没有出现、字段值为null、字段值为空数组、字段值数组的所有元素都为null，则该字段不存在；
5.对于对象字段，只要字段没有出现、字段值是空对象、字段值为null，则该字段不存在；
