Memory 内存索引和lucene文件索引之间有什么区别？

我不熟悉内存索引的概念。我们目前正在使用lucene文件索引技术对记录进行索引和搜索。

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您能告诉我如何实现内存内索引，以及这种类型的索引与lucene文件索引相比有什么优势吗？

检查这个答案，以比较FSDirectory和内存内RAMDIrectory

如何使用RAMDirectory：

RAMDirectory idx = new RAMDirectory(); 
IndexWriterConfig iwc = new IndexWriterConfig(analyzer);
iwc.setOpenMode(OpenMode.CREATE_OR_APPEND);
IndexWriter writer = new IndexWriter(idx, iwc);
Iterator<Map.Entry<String, String>> it = inputCategoryMap.entrySet().iterator();
    while (it.hasNext()) {
        Document doc = new Document();
        Map.Entry<String, String> pair = it.next();
        FieldType contentType = new FieldType();
        contentType.setIndexOptions(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
        contentType.setStored(true);
        contentType.setTokenized(true);
        contentType.setStoreTermVectors(true);
        doc.add(new Field(TITLE, pair.getKey(), TextField.TYPE_STORED));
        doc.add(new Field(CONTENT, pair.getValue(),contentType ));
        dcmnts.add(doc);
    }
    writer.addDocuments(dcmnts);
    writer.commit();
    System.out.println("No of documents added in the index "+writer.maxDoc());
    writer.close();
   System.out.println("Size consumed by Ram  "+idx.ramBytesUsed()+"\nTime Consumed By Lucene  "+stopwatch.getTime(TimeUnit.SECONDS));

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检查此答案以比较FSDirectory和内存中的RAMDIrectory

如何使用RAMDirectory：

RAMDirectory idx = new RAMDirectory(); 
IndexWriterConfig iwc = new IndexWriterConfig(analyzer);
iwc.setOpenMode(OpenMode.CREATE_OR_APPEND);
IndexWriter writer = new IndexWriter(idx, iwc);
Iterator<Map.Entry<String, String>> it = inputCategoryMap.entrySet().iterator();
    while (it.hasNext()) {
        Document doc = new Document();
        Map.Entry<String, String> pair = it.next();
        FieldType contentType = new FieldType();
        contentType.setIndexOptions(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS);
        contentType.setStored(true);
        contentType.setTokenized(true);
        contentType.setStoreTermVectors(true);
        doc.add(new Field(TITLE, pair.getKey(), TextField.TYPE_STORED));
        doc.add(new Field(CONTENT, pair.getValue(),contentType ));
        dcmnts.add(doc);
    }
    writer.addDocuments(dcmnts);
    writer.commit();
    System.out.println("No of documents added in the index "+writer.maxDoc());
    writer.close();
   System.out.println("Size consumed by Ram  "+idx.ramBytesUsed()+"\nTime Consumed By Lucene  "+stopwatch.getTime(TimeUnit.SECONDS));