[ http://issues.apache.org/jira/browse/LUCENE-558?page=comments#action_12376849 ]
Chuck Williams commented on LUCENE-558: --------------------------------------- There is one potentially important benefit of this approach over LUCENE-545. By having the narrower more concrete API (list of fields to load vs. general selector for a variety of loading modes), it is possible to introduce optimizations into readers. The once case where this is done is with ParallelReader. This patch only accesses the reader(s) that contain the field(s) to be loaded, while LUCENE-545 reads the fields from all readers. That can be a significant performance difference, although if using ParallelReaders the application should be able to arrange for this optimization itself. By extending the FieldSelector interface a little, the optimization could be maintained in the more general LUCENE-545. > Selective field loading > ----------------------- > > Key: LUCENE-558 > URL: http://issues.apache.org/jira/browse/LUCENE-558 > Project: Lucene - Java > Type: New Feature > Components: Index > Versions: 2.0 > Environment: All > Reporter: Chuck Williams > Attachments: LuceneTrunk.patch > > Provides a new api, IndexReader.document(int doc, String[] fields). A > document containing only the specified fields is created. The other fields > of the document are not loaded, although unfortunately uncompressed strings > still have to be scanned because the length information in the index is for > UTF-8 encoded chars and not bytes. This is useful for applications that need > quick access to a small subset of the fields. It can be used in conjunction > with or for some uses instead of ParallelReader. > This is a much smaller change for a simpler use case than Lucene-545. No > existing API's are affected. > All the tests pass and new tests are added to verify the feature. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
