elastic探索数据
加载样本数据
curl -u elastic:changeme -XPOST 'localhost:9200/bank/account/_bulk?pretty&refresh' --data-binary "@accounts.json"
使用Search API
两种基本方式使用搜索：
- REST request URI
GET /bank/_search?q=*&sort=account_number:asc&pretty
- REST request body
GET /bank/_search
{
"query":{"match_all":{}},
"sort":[{
{"account_number":"asc"}
}]
}
返回值的含义：
-
took - elastic执行搜索的时间(以毫秒为单位)
-
timed_out - 搜索是否超时
-
_shards - 搜索的分片数量，以及搜索成功/失败的分片数量
-
hits - 搜索返回的结果
-
hits.total - 符合搜索条件的Document数量
-
hits.hits - 实施搜索结果的数组(默认为前10个文档)
-
hits.sort - 排序结果关键字(如果按照分数排序，则不显示)
查询语言
elastic提供了一种用于执行查询的Json风格的特定域的语言
GET /bank/_search
{
"query":{"match_all": {}}
}
query部分代表查询定义，match_all部分代表要查询的类型
可以使用其他参数影响查询结果，例如只返回一条记录
GET /bank/_search
{
"query":{"match_all": {}},
"size":1
}
返回11到20行的记录
GET /bank/_search
{
"query":{"match_all": {}},
"from":10,
"size":10
}
from参数用于指定要从哪个document索引下表开始，size参数指定from参数开始返回多少个document
GET /bank/_search
{
"query": { "match_all": {} },
"sort": { "balance": { "order": "desc" } }
}
执行搜索
返回document的字段
GET /bank/_search
{
"query": { "match_all": {} },
"_source": ["account_number", "balance"]
}
返回account_number为20的记录
GET /bank/_search
{
"query": { "match": { "account_number": 20 } }
}
查询返回地址是mill的记录
GET /bank/_search
{
"query": { "match": { "address": "mill" } }
}
查询返回地址是mill或lane的记录
GET /bank/_search
{
"query": { "match": { "address": "mill lane" } }
}
查询返回地址中包含mill lane的记录
GET /bank/_search
{
"query": { "match_phrase": { "address": "mill lane" } }
}
bool查询允许使用bool逻辑将更下的查询组合成较大的查询(组合条件查询)
GET /bank/_search
{
"query": {
"bool": {
"must": [
{ "match": { "address": "mill" } },
{ "match": { "address": "lane" } }
]
}
}
}
GET /bank/_search
{
"query": {
"bool": {
"should": [
{ "match": { "address": "mill" } },
{ "match": { "address": "lane" } }
]
}
}
}
GET /bank/_search
{
"query": {
"bool": {
"must_not": [
{ "match": { "address": "mill" } },
{ "match": { "address": "lane" } }
]
}
}
}
GET /bank/_search
{
"query": {
"bool": {
"must": [
{ "match": { "age": "40" } }
],
"must_not": [
{ "match": { "state": "ID" } }
]
}
}
}
执行过滤
score是数值类型，代表文档与搜索查询匹配的相对度量。分数越高，文档越相关，分数越低，文档的相关性就越低。
查询并不是总产生分数，特别是当它们仅用于“过滤”文档集合时。
GET /bank/_search
{
"query": {
"bool": {
"must": { "match_all": {} },
"filter": {
"range": {
"balance": {
"gte": 20000,
"lte": 30000
}
}
}
}
}
}
执行聚合
聚合提供从数据中分组和提取统计信息的功能
GET /bank/_search
{
"size": 0,
"aggs": {
"group_by_state": {
"terms": {
"field": "state.keyword"
}
}
}
}
相当于SQL语句为：SELECT state, COUNT() FROM bank GROUP BY state ORDER BY COUNT() DESC。
设置size参数为0是因为要查看显示聚合的结果。
按照state字段分组，并计算balance的平均值
GET /bank/_search
{
"size": 0,
"aggs": {
"group_by_state": {
"terms": {
"field": "state.keyword"
},
"aggs": {
"average_balance": {
"avg": {
"field": "balance"
}
}
}
}
}
}
按照平均balacne进行排序
GET /bank/_search
{
"size": 0,
"aggs": {
"group_by_state": {
"terms": {
"field": "state.keyword",
"order": {
"average_balance": "desc"
}
},
"aggs": {
"average_balance": {
"avg": {
"field": "balance"
}
}
}
}
}
}
按照年龄区间和性别分组，并计算balance
GET /bank/_search
{
"size": 0,
"aggs": {
"group_by_age": {
"range": {
"field": "age",
"ranges": [
{
"from": 20,
"to": 30
},
{
"from": 30,
"to": 40
},
{
"from": 40,
"to": 50
}
]
},
"aggs": {
"group_by_gender": {
"terms": {
"field": "gender.keyword"
},
"aggs": {
"average_balance": {
"avg": {
"field": "balance"
}
}
}
}
}
}
}
}
