# Package org.apache.nutch.indexer

Index content, configure and run indexing and cleaning jobs to add, update, and delete documents from an index. Two tasks are delegated to plugins:

- indexing filters, which fill index fields of each document
- index writer plugins; which send documents to index back-ends (Solr, etc.).

- Interface Summary
  Interface | Description
  --- | ---
  IndexingFilter | Extension point for indexing.
  IndexWriter |

- Class Summary
  Class | Description
  --- | ---
  CleaningJob | The class scans CrawlDB looking for entries with status DB_GONE (404) or DB_DUPLICATE and sends delete requests to indexers for those documents.
  CleaningJob.DBFilter |
  CleaningJob.DeleterReducer |
  IndexerMapReduce | This class is typically invoked from within `IndexingJob` and handles all MapReduce functionality required when undertaking indexing.
  IndexerMapReduce.IndexerMapper |
  IndexerMapReduce.IndexerReducer |
  IndexerOutputFormat |
  IndexingFilters | Creates and caches `IndexingFilter` implementing plugins.
  IndexingFiltersChecker | Reads and parses a URL and run the indexers on it.
  IndexingJob | Generic indexer which relies on the plugins implementing IndexWriter
  IndexWriterConfig |
  IndexWriterParams |
  IndexWriters | Creates and caches `IndexWriter` implementing plugins.
  NutchDocument | A `NutchDocument` is the unit of indexing.
  NutchField | This class represents a multi-valued field with a weight.
  NutchIndexAction | A `NutchIndexAction` is the new unit of indexing holding the document and action information.

- Exception Summary
  Exception | Description
  --- | ---
  IndexingException |