快速了解
字段的 doc_values 属性有两个值， true、false。默认为 true ，即开启。
当 doc_values 为 fasle 时，无法基于该字段排序、聚合、在脚本中访问字段值。
当 doc_values 为 true 时，ES 会增加一个相应的正排索引，这增加的磁盘占用，也会导致索引数据速度慢一些。
示例1: 关闭 doc_values 属性
创建索引
PUT student
{
"mappings" : {
"properties" : {
"name" : {
"type" : "keyword",
"doc_values": false
},
"age" : {
"type" : "integer",
"doc_values": false
}
}
}
}
插入数据
POST _bulk
{ "index" : { "_index" : "student", "_id" : "1" } }
{ "name" : "张三", "age": 12 }
{ "index" : { "_index" : "student", "_id" : "2" } }
{ "name" : "李四", "age": 10 }
{ "index" : { "_index" : "student", "_id" : "3" } }
{ "name" : "王五", "age": 11 }
查询数据
POST student/_search
{
"query": {
"match_all": {}
}
}
执行结果：
{
"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" : "student",
"_type" : "_doc",
"_id" : "1",
"_score" : 1.0,
"_source" : {
"name" : "张三",
"age" : 12
}
},
{
"_index" : "student",
"_type" : "_doc",
"_id" : "2",
"_score" : 1.0,
"_source" : {
"name" : "李四",
"age" : 10
}
},
{
"_index" : "student",
"_type" : "_doc",
"_id" : "3",
"_score" : 1.0,
"_source" : {
"name" : "王五",
"age" : 11
}
}
]
}
}
查询数据并按照age排序，会报错
POST student/_search
{
"query": {
"match_all": {}
},
"sort" : [
{"age": {"order": "desc"}}
],
"from": 0,
"size": 1
}
报错如下：
{
"error": {
"root_cause": [
{
"type": "illegal_argument_exception",
"reason": "Can't load fielddata on [age] because fielddata is unsupported on fields of type [integer]. Use doc values instead."
}
],
"type": "search_phase_execution_exception",
"reason": "all shards failed",
"phase": "query",
"grouped": true,
"failed_shards": [
{
"shard": 0,
"index": "student",
"node": "wFhSfuLwR3OX21eldbRIHg",
"reason": {
"type": "illegal_argument_exception",
"reason": "Can't load fielddata on [age] because fielddata is unsupported on fields of type [integer]. Use doc values instead."
}
}
],
"caused_by": {
"type": "illegal_argument_exception",
"reason": "Can't load fielddata on [age] because fielddata is unsupported on fields of type [integer]. Use doc values instead.",
"caused_by": {
"type": "illegal_argument_exception",
"reason": "Can't load fielddata on [age] because fielddata is unsupported on fields of type [integer]. Use doc values instead."
}
}
},
"status": 400
}
查询数据并按照 name 排序，会报错
和基于 age 的排序报错类似。
获取 age 平均值，会报错
POST student/_search
{
"aggs":{
"age_stat": {
"avg": {"field": "age"}
}
},
"from": 0
}
和上面的排序报错类似。
示例2: 开启 doc_values 属性
创建索引
PUT student
{
"mappings" : {
"properties" : {
"name" : {
"type" : "keyword",
"doc_values": true
},
"age" : {
"type" : "integer",
"doc_values": true
}
}
}
}
插入数据
POST _bulk
{ "index" : { "_index" : "student", "_id" : "1" } }
{ "name" : "张三", "age": 12 }
{ "index" : { "_index" : "student", "_id" : "2" } }
{ "name" : "李四", "age": 10 }
{ "index" : { "_index" : "student", "_id" : "3" } }
{ "name" : "王五", "age": 11 }
查询数据
POST student/_search
{
"query": {
"match_all": {}
}
}
执行结果：
{
"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" : "student",
"_type" : "_doc",
"_id" : "1",
"_score" : 1.0,
"_source" : {
"name" : "张三",
"age" : 12
}
},
{
"_index" : "student",
"_type" : "_doc",
"_id" : "2",
"_score" : 1.0,
"_source" : {
"name" : "李四",
"age" : 10
}
},
{
"_index" : "student",
"_type" : "_doc",
"_id" : "3",
"_score" : 1.0,
"_source" : {
"name" : "王五",
"age" : 11
}
}
]
}
}
查询数据并按照age排序，正常执行
POST student/_search
{
"query": {
"match_all": {}
},
"sort" : [
{"age": {"order": "desc"}}
],
"from": 0,
"size": 1
}
响应：
{
"took" : 1,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 3,
"relation" : "eq"
},
"max_score" : null,
"hits" : [
{
"_index" : "student",
"_type" : "_doc",
"_id" : "1",
"_score" : null,
"_source" : {
"name" : "张三",
"age" : 12
},
"sort" : [
12
]
}
]
}
}
查询数据并按照 name 排序，正常执行
POST student/_search
{
"query": {
"match_all": {}
},
"sort" : [
{"name": {"order": "desc"}}
],
"from": 0,
"size": 1
}
响应:
{
"took" : 1,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 3,
"relation" : "eq"
},
"max_score" : null,
"hits" : [
{
"_index" : "student",
"_type" : "_doc",
"_id" : "3",
"_score" : null,
"_source" : {
"name" : "王五",
"age" : 11
},
"sort" : [
"王五"
]
}
]
}
}
获取 age 平均值，正常执行
POST student/_search
{
"aggs":{
"age_stat": {
"avg": {"field": "age"}
}
},
"from": 0,
"size": 0
}
响应：
{
"took" : 1,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 3,
"relation" : "eq"
},
"max_score" : null,
"hits" : [ ]
},
"aggregations" : {
"age_stat" : {
"value" : 11.0
}
}
}