三種場景
-
最佳字段 (Best Fields)
- 當字段之間相互競爭，?相互關聯。例如 title 和 body 這樣的字段。評分來?最匹配字段
-
多數字段 (Most Fields)
- 處理英?內容時：?種常?的?段是，在主字段( English Analyzer)，抽取詞?，加?同義詞，以 匹配更多的?檔。相同的?本，加??字段(Standard Analyzer)，以提供更加精確的匹配。其他字 段作為匹配?檔提?相關度的信號。匹配字段越多則越好
-
混合字段 (Cross Field)
- 對于某些實體，例如?名，地址，圖書信息。需要在多個字段中確定信息，單個字段只能作為整體 的?部分。希望在任何這些列出的字段中找到盡可能多的詞
Multi Match Query
Best Fields 是默認類型，可以不?指定
Minimum should match 等參數可以傳遞到?成的 query 中
POST blogs/_search
{
"query": {
"multi_match": {
"type": "best_fields",
"query": "Quick pets",
"fields": ["title","body"],
"tie_breaker": 0.2,
"minimum_should_match": "20%"
}
}
}
?個查詢案例
- 英?分詞器，導致精確度降低，時態信息丟失
PUT /titles
{
"mappings": {
"properties": {
"title": {
"type": "text",
"analyzer": "english"
}
}
}
}
POST titles/_bulk
{ "index": { "_id": 1 }}
{ "title": "My dog barks" }
{ "index": { "_id": 2 }}
{ "title": "I see a lot of barking dogs on the road " }
GET titles/_search
{
"query": {
"match": {
"title": "barking dogs"
}
}
}
image.png
使?多數字段匹配解決
??度匹配字段 title 包括盡可能多的?檔——以提 升召回率——同時?使?字段 title.std 作為信號 將 相關度更?的?檔置于結果頂部。
每個字段對于最終評分的貢獻可以通過?定義值 boost 來控制。?如，使 title 字段更為重要， 這樣同時也降低了其他信號字段的作?
DELETE /titles
PUT /titles
{
"mappings": {
"properties": {
"title": {
"type": "text",
"analyzer": "english",
"fields": {"std": {"type": "text","analyzer": "standard"}}
}
}
}
}
POST titles/_bulk
{ "index": { "_id": 1 }}
{ "title": "My dog barks" }
{ "index": { "_id": 2 }}
{ "title": "I see a lot of barking dogs on the road " }
GET /titles/_search
{
"query": {
"multi_match": {
"query": "barking dogs",
"type": "most_fields",
"fields": [ "title", "title.std" ]
}
}
}
GET /titles/_search
{
"query": {
"multi_match": {
"query": "barking dogs",
"type": "most_fields",
"fields": [ "title^10", "title.std" ]
}
}
}
跨字段搜索
?法使? Operator
可以? copy_to 解決，但是需要額外的存儲空間
PUT address/_doc/1
{
"street": "5 Poland Street",
"city": "London",
"country": "United Kingdom",
"postcode": "W1V 3Dg"
}
POST address/_search
{
"query": {
"multi_match": {
"query": "Poland Street W1V",
"type": "most_fields",
"fields": ["street", "city", "country", "postcode"]
}
}
}
跨字段搜索 [cross_fields解決]
POST address/_search
{
"query": {
"multi_match": {
"query": "Poland Street W1V",
"type": "cross_fields",
"operator": "and",
"fields": ["street", "city", "country", "postcode"]
}
}
}
?持使? Operator
與 copy_to, 相?，其中?個優勢就是它可以在搜索時為單個字段提升權重。
本節知識點回顧
Multi Match 查詢的基本語法
查詢的類型
最佳字段 / 多數字段 / 跨字段
Boosting
控制 Precision
以及使??字段多數字段算分，控制
使? Operator
課程demo
POST blogs/_search
{
"query": {
"dis_max": {
"queries": [
{ "match": { "title": "Quick pets" }},
{ "match": { "body": "Quick pets" }}
],
"tie_breaker": 0.2
}
}
}
POST blogs/_search
{
"query": {
"multi_match": {
"type": "best_fields",
"query": "Quick pets",
"fields": ["title","body"],
"tie_breaker": 0.2,
"minimum_should_match": "20%"
}
}
}
POST books/_search
{
"multi_match": {
"query": "Quick brown fox",
"fields": "*_title"
}
}
POST books/_search
{
"multi_match": {
"query": "Quick brown fox",
"fields": [ "*_title", "chapter_title^2" ]
}
}
DELETE /titles
PUT /titles
{
"settings": {
"number_of_replicas": 1
},
"mappings": {
"properties": {
"title": {
"type": "text",
"analyzer": "english",
"fields": {
"std": {
"type": "text",
"analyzer": "standard"
}
}
}
}
}
}
PUT /titles
{
"mappings": {
"properties": {
"title": {
"type": "text",
"analyzer": "english"
}
}
}
}
POST titles/_bulk
{ "index": { "_id": 1 }}
{ "title": "My dog barks" }
{ "index": { "_id": 2 }}
{ "title": "I see a lot of barking dogs on the road " }
GET titles/_search
{
"query": {
"match": {
"title": "barking dogs"
}
}
}
DELETE /titles
PUT /titles
{
"mappings": {
"properties": {
"title": {
"type": "text",
"analyzer": "english",
"fields": {"std": {"type": "text","analyzer": "standard"}}
}
}
}
}
POST titles/_bulk
{ "index": { "_id": 1 }}
{ "title": "My dog barks" }
{ "index": { "_id": 2 }}
{ "title": "I see a lot of barking dogs on the road " }
GET /titles/_search
{
"query": {
"multi_match": {
"query": "barking dogs",
"type": "most_fields",
"fields": [ "title", "title.std" ]
}
}
}
GET /titles/_search
{
"query": {
"multi_match": {
"query": "barking dogs",
"type": "most_fields",
"fields": [ "title^10", "title.std" ]
}
}
}
PUT address/_doc/1
{
"street": "5 Poland Street",
"city": "London",
"country": "United Kingdom",
"postcode": "W1V 3Dg"
}
POST address/_search
{
"query": {
"multi_match": {
"query": "Poland Street W1V",
"type": "most_fields",
"fields": ["street", "city", "country", "postcode"]
}
}
}
POST address/_search
{
"query": {
"multi_match": {
"query": "Poland Street W1V",
"type": "cross_fields",
"operator": "and",
"fields": ["street", "city", "country", "postcode"]
}
}
}
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