[ http://issues.apache.org/jira/browse/LUCENE-558?page=comments#action_12377043 ]
Chuck Williams commented on LUCENE-558: --------------------------------------- Grant, I think that's a great idea. I'll look at adding the extension to support the reader optimization for ParallelReader. Essentially it will provide a means for FieldSelectors to declare the complete list of fields that will ever be loaded as an optional operation. If this is declared, then ParallelReader (for example) can access only relevant readers. There is another extension I'll add unless there are objections. The idea is to extend the lazy loading to support streaming through readerValue() and a new streamValue() (the former for uncompressed String fields and the latter for compressed String and binary fields). This will support getting a reader or stream to obtain the field value rather than reading it all into a String or byte[]. This seems like a huge advantage in many applications (e.g., my current one). It would be an upward incompatibility to support readerValue() this way (since it would no longer be true that exactly one of stringValue(), binaryValue() and readerValue() is non-null). So it could be a different method, or limited to a new Fieldable subtype. The reader returned will be full function -- e.g., it is easy to support arbitrary mark() and reset(). > 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]
