The Completion Suggester
Completion Suggester 提供了“⾃动完成” (Auto Complete) 的功能。⽤户每输⼊⼀个 字符，就需要即时发送⼀个查询请求到后段查找匹配项
对性能要求⽐较苛刻。Elasticsearch 采⽤了不同的数据结构，并⾮通过倒排索引来完成。
⽽是将 Analyze 的数据编码成 FST 和索引⼀起存放。FST 会被 ES 整个加载进内存， 速度很快FST 只能⽤于前缀查找
使⽤ Completion Suggester 的⼀些步骤
定义 Mapping，使⽤ “completion” type
索引数据
运⾏ “suggest” 查询，得到搜索建议
PUT articles
{
"mappings": {
"properties": {
"title_completion":{
"type": "completion"
}
}
}
}
索引数据
POST articles/_bulk
{ "index" : { } }
{ "title_completion": "lucene is very cool"}
{ "index" : { } }
{ "title_completion": "Elasticsearch builds on top of lucene"}
{ "index" : { } }
{ "title_completion": "Elasticsearch rocks"}
{ "index" : { } }
{ "title_completion": "elastic is the company behind ELK stack"}
{ "index" : { } }
{ "title_completion": "Elk stack rocks"}
{ "index" : {} }
搜索数据
POST articles/_search?pretty
{
"size": 0,
"suggest": {
"article-suggester": {
"prefix": "elk ",
"completion": {
"field": "title_completion"
}
}
}
}
res
什么是 Context Suggester
Completion Suggester 的扩展
-
可以在搜索中加⼊更多的上下⽂信息，例如，输⼊ “star”
咖啡相关：建议 “Starbucks”
电影相关：”star wars”
实现 Context Suggester
-
可以定义两种类型的 Context
Category – 任意的字符串
Geo – 地理位置信息
-
实现 Context Suggester 的具体步骤
定制⼀个 Mapping
索引数据，并且为每个⽂档加⼊ Context 信息
结合 Context 进⾏ Suggestion 查询
定义 Mapping
-
增加 Contexts
Type
name
PUT comments/_mapping
{
"properties": {
"comment_autocomplete":{
"type": "completion",
"contexts":[{
"type":"category",
"name":"comment_category"
}]
}
}
}
索引数据
image.png
不同的上下⽂，⾃动提示
POST comments/_search
{
"suggest": {
"MY_SUGGESTION": {
"prefix": "sta",
"completion":{
"field":"comment_autocomplete",
"contexts":{
"comment_category":"coffee"
}
}
}
}
}
image.png
精准度和召回率
-
精准度
- Completion > Phrase > Term
-
召回率
- Term > Phrase > Completion
-
性能
- Completion > Phrase > Term
本节知识点回顾
Completion Suggester，对性能要求⽐较苛刻。采⽤了不同的数据结构，并⾮通过倒排
索引来完成。⽽是将 Analyze 的数据编码成 FST 和索引⼀起存放。FST 会被 ES 整个 加载进内存，速度很快需要设置特定的 Mapping
Context Completion Suggester ⽀持结合不同的上下⽂，给出推荐
课程demo
DELETE articles
PUT articles
{
"mappings": {
"properties": {
"title_completion":{
"type": "completion"
}
}
}
}
POST articles/_bulk
{ "index" : { } }
{ "title_completion": "lucene is very cool"}
{ "index" : { } }
{ "title_completion": "Elasticsearch builds on top of lucene"}
{ "index" : { } }
{ "title_completion": "Elasticsearch rocks"}
{ "index" : { } }
{ "title_completion": "elastic is the company behind ELK stack"}
{ "index" : { } }
{ "title_completion": "Elk stack rocks"}
{ "index" : {} }
POST articles/_search?pretty
{
"size": 0,
"suggest": {
"article-suggester": {
"prefix": "elk ",
"completion": {
"field": "title_completion"
}
}
}
}
DELETE comments
PUT comments
PUT comments/_mapping
{
"properties": {
"comment_autocomplete":{
"type": "completion",
"contexts":[{
"type":"category",
"name":"comment_category"
}]
}
}
}
POST comments/_doc
{
"comment":"I love the star war movies",
"comment_autocomplete":{
"input":["star wars"],
"contexts":{
"comment_category":"movies"
}
}
}
POST comments/_doc
{
"comment":"Where can I find a Starbucks",
"comment_autocomplete":{
"input":["starbucks"],
"contexts":{
"comment_category":"coffee"
}
}
}
POST comments/_search
{
"suggest": {
"MY_SUGGESTION": {
"prefix": "sta",
"completion":{
"field":"comment_autocomplete",
"contexts":{
"comment_category":"coffee"
}
}
}
}
}
