[ http://issues.apache.org/jira/browse/LUCENE-545?page=all ]
Grant Ingersoll resolved LUCENE-545:
------------------------------------
Resolution: Fixed
Thanks, Chuck, for the assistance!
> Field Selection and Lazy Field Loading
> --------------------------------------
>
> Key: LUCENE-545
> URL: http://issues.apache.org/jira/browse/LUCENE-545
> Project: Lucene - Java
> Type: New Feature
> Components: Store
> Versions: 2.0.0
> Reporter: Grant Ingersoll
> Assignee: Grant Ingersoll
> Priority: Minor
> Attachments: LazyFields.tar.gz, fieldSelectorPatch.txt, newFiles.tar.gz
>
> The patch to come shortly implements a Field Selection and Lazy Loading
> mechanism for Document loading on the IndexReader.
> It introduces a FieldSelector interface that defines the accept method:
> FieldSelectorResult accept(String fieldName);
> (Perhaps we want to expand this to take in other parameters such as the field
> metadata (term vector, etc.))
> Anyone can implement a FieldSelector to define how they want to load fields
> for a Document.
> The FieldSelectorResult can be one of four values: LOAD, LAZY_LOAD, NO_LOAD,
> LOAD_AND_BREAK.
> The FieldsReader, as it is looping over the FieldsInfo, applies the
> FieldSelector to determine what should be done with the current field.
> I modeled this after the java.io.FileFilter mechanism. There are two
> implementations to date: SetBasedFieldSelector and LoadFirstFieldSelector.
> The former takes in two sets of field names, one to load immed. and one to
> load lazily. The latter returns LOAD_AND_BREAK on the first field
> encountered. See TestFieldsReader for examples.
> It should support UTF-8 (I borrowed code from Issue 509, thanks!). See
> TestFieldsReader for examples
> I added an expert method on IndexInput named skipChars that takes in the
> number of characters to skip. This is a compromise on changing the file
> format of the fields to better support seeking. It does some of the work of
> readChars, but not all of it. It doesn't require buffer storage and it
> doesn't do the bitwise operations. It just reads in the appropriate number
> of bytes and promptly ignores them. This is useful for skipping non-binary,
> non-compressed stored fields.
> The biggest change is by far the introduction of the Fieldable interface (as
> per Doug's suggestion from a mailing list email on Lazy Field loading from a
> while ago). Field is now a Fieldable. All uses of Field have been changed
> to use Fieldable. FieldsReader.LazyField also implements Fieldable.
> Lazy Field loading is now implemented. It has a major caveat (that is
> Documented) in that it clones the underlying IndexInput upon lazy access to
> the Field value. IT IS UNDEFINED whether a Lazy Field can be loaded after
> the IndexInput parent has been closed (although, from what I saw, it does
> work). I thought about adding a reattach method, but it seems just as easy
> to reload the document. See the TestFieldsReader and DocHelper for examples.
> I updated a couple of other tests to reflect the new fields that are on the
> DocHelper document.
> All tests pass.
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