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From "Steven Tamm (JIRA)" <>
Subject [jira] Updated: (LUCENE-509) Performance optimization when retrieving a single field from a document
Date Thu, 02 Mar 2006 20:35:40 GMT
     [ ]

Steven Tamm updated LUCENE-509:

    Attachment: DocField_3.patch

This includes a UTF-8 test.  It fails with the first patch and works with the second.

I specifically chose to return only the first Field because otherwise you need to read all
the fields in the document.  Now, if the field appears near the beginning of the list of fields,
it requires less IO to retrieve

> Performance optimization when retrieving a single field from a document
> -----------------------------------------------------------------------
>          Key: LUCENE-509
>          URL:
>      Project: Lucene - Java
>         Type: Improvement
>   Components: Index
>     Versions: 1.9, 2.0
>     Reporter: Steven Tamm
>  Attachments: DocField.patch, DocField_2.patch, DocField_3.patch
> If you just want to retrieve a single field from a Document, the only way to do it is
to retrieve all the fields from the Document and then search it.  This patch is an optimization
that allows you retrieve a specific field from a document without instantiating a lot of field
and string objects.  This reduces our memory consumption on a per query basis by around around
20% when a lot of documents are returned.
> I've added a lot of comments saying you should only call it if you only ever need one
field.  There's also a unit test.

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