Elasticsearch - 分页查询
前言
随着数据量的 不断增大，查询结果也展示的越来越长，很多时候，我们仅是查询几条数据，不用全部显示出来。那又该怎么做呢？这里就要用到分页了。
准备数据
PUT zhifou/doc/1
{
"name":"顾老二",
"age":30,
"from": "gu",
"desc": "皮肤黑、武器长、性格直",
"tags": ["黑", "长", "直"]
}
PUT zhifou/doc/2
{
"name":"大娘子",
"age":18,
"from":"sheng",
"desc":"肤白貌美，娇憨可爱",
"tags":["白", "富","美"]
}
PUT zhifou/doc/3
{
"name":"龙套偏房",
"age":22,
"from":"gu",
"desc":"mmp，没怎么看，不知道怎么形容",
"tags":["造数据", "真","难"]
}
PUT zhifou/doc/4
{
"name":"石头",
"age":29,
"from":"gu",
"desc":"粗中有细，狐假虎威",
"tags":["粗", "大","猛"]
}
PUT zhifou/doc/5
{
"name":"魏行首",
"age":25,
"from":"广云台",
"desc":"仿佛兮若轻云之蔽月,飘飘兮若流风之回雪,mmp，最后竟然没有嫁给顾老二！",
"tags":["闭月","羞花"]
}
分页查询：from/size
我们来看看elasticsearch是怎么将结果分页的：
GET zhifou/doc/_search
{
"query": {
"match_all": {}
},
"sort": [
{
"age": {
"order": "desc"
}
}
],
"from": 2,
"size": 1
}
上例，首先以age降序排序，查询所有。并且在查询的时候，添加两个属性from和size来控制查询结果集的数据条数。
- from：从哪开始查
- size：返回几条结果
如上例的结果：
{
"took" : 0,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : null,
"hits" : [
{
"_index" : "zhifou",
"_type" : "doc",
"_id" : "5",
"_score" : null,
"_source" : {
"name" : "魏行首",
"age" : 25,
"from" : "广云台",
"desc" : "仿佛兮若轻云之蔽月,飘飘兮若流风之回雪,mmp，最后竟然没有嫁给顾老二！",
"tags" : [
"闭月",
"羞花"
]
},
"sort" : [
25
]
}
]
}
}
上例中，在返回的结果集中，从第2条开始，返回1条数据。
那如果想要从第2条开始，返回2条结果怎么做呢？
GET zhifou/doc/_search
{
"query": {
"match_all": {}
},
"sort": [
{
"age": {
"order": "desc"
}
}
],
"from": 2,
"size": 2
}
上例中，我们指定from为2，意为从第2条开始返回，返回多少呢？size意为2条。
还可以这样：
GET zhifou/doc/_search
{
"query": {
"match_all": {}
},
"sort": [
{
"age": {
"order": "desc"
}
}
],
"from": 4,
"size": 2
}
上例中，从第4条开始返回2条数据。
结果如下：
{
"took" : 0,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : null,
"hits" : [
{
"_index" : "zhifou",
"_type" : "doc",
"_id" : "2",
"_score" : null,
"_source" : {
"name" : "大娘子",
"age" : 18,
"from" : "sheng",
"desc" : "肤白貌美，娇憨可爱",
"tags" : [
"白",
"富",
"美"
]
},
"sort" : [
18
]
}
]
}
}
上例中仅有一条数据，那是为啥呢？因为我们现在只有5条数据，从第4条开始查询，就只有1条符合条件，所以，就返回了1条数据。
学到这里，我们也可以看到，我们的查询条件越来越多，开始仅是简单查询，慢慢增加条件查询，增加排序，对返回结果进行限制。所以，我们可以说：对于elasticsearch来说，所有的条件都是可插拔的，彼此之间用,分割。比如说，我们在查询中，仅对返回结果进行限制：
GET zhifou/doc/_search
{
"query": {
"match_all": {}
},
"from": 4,
"size": 2
}
上例中，在所有的返回结果中，结果从4开始返回2条数据。
{
"took" : 0,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : 5,
"max_score" : 1.0,
"hits" : [
{
"_index" : "zhifou",
"_type" : "doc",
"_id" : "3",
"_score" : 1.0,
"_source" : {
"name" : "龙套偏房",
"age" : 22,
"from" : "gu",
"desc" : "mmp，没怎么看，不知道怎么形容",
"tags" : [
"造数据",
"真",
"难"
]
}
}
]
}
}
但我们只有1条符合条件的数据。
欢迎斧正，that's all
