![]() ![]() When parsing completes, we will have an input stream that needs to be indexed. One of widely known tools we can use to parse documents is Apache Tika. In extracting procedure, it is common to use a versatile parser that can extract textual contents from documents. Indexing with Lucene breaks down into three main operations: extracting text from source documents, analyzing it, and saving it to the index Typically we can divide indexing documents into two distinct procedures, extracting text and creating index (Figure 2).įigure 2. Instead, all segments will be stored in flat files. Furthermore, this strategy also allows Lucene to avoid complex B-trees to store segments. ![]() This strategy ensures there is no conflict between reading writing indexes. Instead, Lucene creates new segments when the document collection changes and later, it merges segments into new ones and deletes the old segments. More importantly, the segment will never be modified. The approach of merging and deleting segments is considerably useful as the document collection does not change frequently. After merging, all greyed segments will be removed and in total, Lucene merged 5 times after the indexing finishes. The process is similar when Lucene keeps merging a group of 3 segments until there is no more segment to merge. Lucene repeatedly creates a segment for a document and periodically merges a group of 3 documents. In the example, there are 14 documents in the collection. The index diagram with the merge factor b is 3įigure 1 illustrates an example of an index, where the merge factor equals three. ![]()
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