ElasticSearch22：初识搜索引擎_search结果深入解析，timeout揭秘
1.我们如果发送一个搜索请求，会得到一个搜索结果
执行一条简单的搜索GET /_search
{
"took": 26,
"timed_out": false,
"_shards": {
"total": 11,
"successful": 11,
"skipped": 0,
"failed": 0
},
"hits": {
"total": 21,
"max_score": 1,
"hits": [
{
"_index": ".kibana",
"_type": "doc",
"_id": "config:6.1.1",
"_score": 1,
"_source": {
"type": "config",
"updated_at": "2017-12-25T08:15:46.917Z",
"config": {
"buildNum": 16350,
"defaultIndex": "cdf712f0-e94b-11e7-a430-13b2f048e43f"
}
}
}
}
}
took：表示请求花费的时间，单位ms
_shard：shards fail的条件（primary和replica全部挂掉），不影响其他shard。默认情况下来说，一个搜索请求，会打到一个index的所有primary shard上去，当然了，每个primary shard都会有一个或多个replica shard，所以请求也可以到primary shard的其中一个replica shard上去。
hits.total 本次搜索，返回几条搜索结果
hits.max_score：本次搜索的所有结果中，最大的相关度分数是多少，每一条document对于search对于search的相关度，越相关_score分数越大，排名越靠前。
hits.hits ：默认情况下，只查询出前面的10条数据。完整数据，_score按倒叙排序，max_source
timed_out：默认无timeout，latency平衡completeness，手动指定timeout，timeout查询指定机制
2. 为什么默认没有timeout？timeout查询指定机制
比如说，你的搜索特别慢，每个shard都要花费好几分钟才能查询出来所有的数据，那么你的搜索请求也会等待好几分钟之后才会返回
我们有些搜索应用，对时间是很敏感的，比如说电商网站，也不会说让用户等10分钟，才能等到一次搜索请求的结果，如果那样，用户基本都没了。
timeout机制，指定每个shard就只能在timeout的时间范围内，将搜索到的部分数据（也可能是全部数据），直接立即返回给client程序，而不是等到所有的数据全部搜索出来以后再返回。
确保说，一次搜索请求可以在用户指定的timeout时长内完成，为一些时间敏感的搜索应用提供良好的支持。 可以指定timeout时长，需要带上单位
例子：
GET /_search?timeout=1ms
执行结果：
{
"took": 11,
"timed_out": false,
"_shards": {
"total": 11,
"successful": 11,
"skipped": 0,
"failed": 0
},
"hits": {
"total": 21,
"max_score": 1,
"hits": [
{
"_index": ".kibana",
"_type": "doc",
"_id": "config:6.1.1",
"_score": 1,
"_source": {
"type": "config",
"updated_at": "2017-12-25T08:15:46.917Z",
"config": {
"buildNum": 16350,
"defaultIndex": "cdf712f0-e94b-11e7-a430-13b2f048e43f"
}
}
},
{
"_index": ".kibana",
"_type": "doc",
"_id": "index-pattern:cdf712f0-e94b-11e7-a430-13b2f048e43f",
"_score": 1,
"_source": {
"type": "index-pattern",
"updated_at": "2017-12-27T02:05:13.335Z",
"index-pattern": {
"title": "ecommerce",
"fields": """[{"name":"_id","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":true,"readFromDocValues":false},{"name":"_index","type":"string","count":4,"scripted":false,"searchable":true,"aggregatable":true,"readFromDocValues":false},{"name":"_score","type":"number","count":0,"scripted":false,"searchable":false,"aggregatable":false,"readFromDocValues":false},{"name":"_source","type":"_source","count":0,"scripted":false,"searchable":false,"aggregatable":false,"readFromDocValues":false},{"name":"_type","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":true,"readFromDocValues":false},{"name":"desc","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":false,"readFromDocValues":false},{"name":"desc.keyword","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":true,"readFromDocValues":true},{"name":"name","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":false,"readFromDocValues":false},{"name":"name.keyword","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":true,"readFromDocValues":true},{"name":"price","type":"number","count":0,"scripted":false,"searchable":true,"aggregatable":true,"readFromDocValues":true},{"name":"producer","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":false,"readFromDocValues":false},{"name":"producer.keyword","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":true,"readFromDocValues":true},{"name":"tags","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":false,"readFromDocValues":false},{"name":"tags.keyword","type":"string","count":0,"scripted":false,"searchable":true,"aggregatable":true,"readFromDocValues":true}]"""
}
}
},
{
"_index": "ecommerce",
"_type": "product",
"_id": "5",
"_score": 1,
"_source": {
"name": "zhuyan yagao",
"desc": "meibai jiankang",
"price": 54,
"producer": "zhuyan producer",
"tags": [
"fangzhu",
"meibai",
"jiankang"
]
}
},
{
"_index": "test_index",
"_type": "test_type",
"_id": "10",
"_score": 1,
"_source": {
"test_field": "test_201712291052",
"test_field2": "test002"
}
},
{
"_index": "test_index",
"_type": "test_type",
"_id": "QIBLoGABN5gu7um0xJGZ",
"_score": 1,
"_source": {
"ids": [
1,
2
]
}
},
{
"_index": "test_index",
"_type": "test_type",
"_id": "8",
"_score": 1,
"_source": {
"test_field": "xxx81",
"test_field2": "xxx00000000"
}
},
{
"_index": "ecommerce",
"_type": "product",
"_id": "4",
"_score": 1,
"_source": {
"name": "yayale yagao",
"desc": "gaoxiao meibai",
"price": 100,
"producer": "yayale producer",
"tags": [
"fangzhu",
"meibai",
"qingxin"
]
}
},
{
"_index": "ecommerce",
"_type": "product",
"_id": "1131mmABEP2XuYqpoflk",
"_score": 1,
"_source": {
"name": "heiren yagao",
"desc": "gaoxiao meibai",
"price": 100,
"producer": "heiren producer",
"tags": [
"fangzhu",
"meibai",
"qingxin"
]
}
},
{
"_index": "ecommerce",
"_type": "product",
"_id": "2",
"_score": 1,
"_source": {
"query": {
"match": {
"name": "yao"
}
}
}
},
{
"_index": "test_index",
"_type": "test_type",
"_id": "2",
"_score": 1,
"_source": {
"test_field": "xxxxx000"
}
}
]
}
}