Specialized queries

• more_like_this query(相似度查询)

这个查询能检索到与指定文本、文档或者文档集合相似的文档。

查看More Like This Query

String[] fields = {"name.first", "name.last"};                 //fields
String[] texts = {"text like this one"};                       //text
Item[] items = null;

QueryBuilder qb = moreLikeThisQuery(fields, texts, items)
    .minTermFreq(1)                                            //ignore threshold
    .maxQueryTerms(12);                                        //max num of Terms in generated queries

• script query

该查询允许脚本充当过滤器。 另请参阅 function_score query 。

查看Script Query

QueryBuilder qb = scriptQuery(
    new Script("doc['num1'].value > 1") //inlined script
);

如果已经在每个数据节点上存储名为 `myscript.painless 的脚本，请执行以下操作：

doc['num1'].value > params.param1

然后使用：

QueryBuilder qb = scriptQuery(
    new Script(
        ScriptType.FILE,                       //脚本类型 ScriptType.FILE, ScriptType.INLINE， ScriptType.INDEXED
        "painless",                            //Scripting engine 脚本引擎
        "myscript",                            //Script name 脚本名
        Collections.singletonMap("param1", 5)) //Parameters as a Map of <String, Object>
);

• Percolate Query

查看Percolate Query

Settings settings = Settings.builder().put("cluster.name", "elasticsearch").build();
TransportClient client = new PreBuiltTransportClient(settings);
client.addTransportAddress(new InetSocketTransportAddress(new InetSocketAddress(InetAddresses.forString("127.0.0.1"), 9300)));

在可以使用percolate查询之前，应该添加percolator映射，并且应该对包含percolator查询的文档建立索引：

// create an index with a percolator field with the name 'query':
client.admin().indices().prepareCreate("myIndexName")
                        .addMapping("query", "query", "type=percolator")
                        .addMapping("docs", "content", "type=text")
                        .get();

//This is the query we're registering in the percolator
QueryBuilder qb = termQuery("content", "amazing");

//Index the query = register it in the percolator
client.prepareIndex("myIndexName", "query", "myDesignatedQueryName")
    .setSource(jsonBuilder()
        .startObject()
            .field("query", qb) // Register the query
        .endObject())
    .setRefreshPolicy(RefreshPolicy.IMMEDIATE) // Needed when the query shall be available immediately
    .get();

在上面的index中query名为 myDesignatedQueryName

为了检查文档注册查询,使用这个代码:

//Build a document to check against the percolator
XContentBuilder docBuilder = XContentFactory.jsonBuilder().startObject();
docBuilder.field("content", "This is amazing!");
docBuilder.endObject(); //End of the JSON root object

PercolateQueryBuilder percolateQuery = new PercolateQueryBuilder("query", "docs", docBuilder.bytes());

// Percolate, by executing the percolator query in the query dsl:
SearchResponse response = client().prepareSearch("myIndexName")
        .setQuery(percolateQuery))
        .get();
//Iterate over the results
for(SearchHit hit : response.getHits()) {
    // Percolator queries as hit
}