不能用lucene IndexWriter.deleteDocuments(术语)删除文档

Question

这两天来一直在挣扎，只是不能用indexWriter.deleteDocuments(term)删除文档

在这里，我将把进行测试的代码放在这里，希望有人能指出我做错了什么，已经尝试过的事情：

1. 将lucene版本从2.x更新为5.x
2. 使用indexWriter.deleteDocuments()而不是indexReader.deleteDocuments()
3. 将indexOption配置为NONE或DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS

在这里，代码：

import org.apache.lucene.analysis.core.SimpleAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.FieldType;
import org.apache.lucene.index.*;
import org.apache.lucene.queryparser.classic.ParseException;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;

import java.io.IOException;
import java.nio.file.Paths;

public class TestSearch {
    static SimpleAnalyzer analyzer = new SimpleAnalyzer();

    public static void main(String[] argvs) throws IOException, ParseException {
        generateIndex("5836962b0293a47b09d345f1");
        query("5836962b0293a47b09d345f1");
        delete("5836962b0293a47b09d345f1");
        query("5836962b0293a47b09d345f1");

    }

    public static void generateIndex(String id) throws IOException {
        Directory directory = FSDirectory.open(Paths.get("/tmp/test/lucene"));
        IndexWriterConfig config = new IndexWriterConfig(analyzer);
        IndexWriter iwriter = new IndexWriter(directory, config);
        FieldType fieldType = new FieldType();
        fieldType.setStored(true);
        fieldType.setIndexOptions(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
        Field idField = new Field("_id", id, fieldType);
        Document doc = new Document();
        doc.add(idField);
        iwriter.addDocument(doc);
        iwriter.close();

    }

    public static void query(String id) throws ParseException, IOException {
        Query query = new QueryParser("_id", analyzer).parse(id);
        Directory directory = FSDirectory.open(Paths.get("/tmp/test/lucene"));
        IndexReader ireader  = DirectoryReader.open(directory);
        IndexSearcher isearcher = new IndexSearcher(ireader);
        ScoreDoc[] scoreDoc = isearcher.search(query, 100).scoreDocs;
        for(ScoreDoc scdoc: scoreDoc){
            Document doc = isearcher.doc(scdoc.doc);
            System.out.println(doc.get("_id"));
        }
    }

    public static void delete(String id){
        try {
             Directory directory = FSDirectory.open(Paths.get("/tmp/test/lucene"));
            IndexWriterConfig config = new IndexWriterConfig(analyzer);
            IndexWriter iwriter = new IndexWriter(directory, config);
            Term term = new Term("_id", id);
            iwriter.deleteDocuments(term);
            iwriter.commit();
            iwriter.close();
        }catch (IOException e){
            e.printStackTrace();
        }
    }
}

首先generateIndex()将在/tmp/test/lucene中生成索引，query()将显示id将被成功查询，然后delete()希望删除文档，但query()将再次证明删除操作失败。

下面是pom依赖关系，以防有人需要进行测试

    <dependency>
        <groupId>org.apache.lucene</groupId>
        <artifactId>lucene-core</artifactId>
        <version>5.5.4</version>
        <type>jar</type>
    </dependency>
    <dependency>
        <groupId>org.apache.lucene</groupId>
        <artifactId>lucene-analyzers-common</artifactId>
        <version>5.5.4</version>
    </dependency>
    <dependency>
        <groupId>org.apache.lucene</groupId>
        <artifactId>lucene-queryparser</artifactId>
        <version>5.5.4</version>
    </dependency>
    <dependency>
        <groupId>org.apache.lucene</groupId>
        <artifactId>lucene-analyzers-smartcn</artifactId>
        <version>5.5.4</version>
    </dependency>

绝望地想得到答案。

Answer 1

你的问题在分析器里。SimpleAnalyzer将符号定义为字母的最大字符串(StandardAnalyzer，甚至WhitespaceAnalyzer，是更典型的选择)，因此您正在索引的值被拆分为标记："b“、"a”、"b“、"d”、"f“。但是，您定义的delete方法并不通过分析器，而只是创建了一个原始术语。如果尝试将main替换为以下内容，则可以看到此操作：

generateIndex("5836962b0293a47b09d345f1");
query("5836962b0293a47b09d345f1");
delete("b");
query("5836962b0293a47b09d345f1");

作为一般规则，查询和术语等不进行分析，QueryParser会这样做。

对于一个标识符字段，您可能根本不想分析这个字段。在这种情况下，将其添加到FieldType中：

fieldType.setTokenized(false);

然后，您将不得不更改查询(再次，QueryParser分析)，并使用TermQuery代替。

Query query = new TermQuery(new Term("_id", id));