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From "Vitaly Funstein" <vfunst...@gmail.com>
Subject RE: Lucene Empty Non-empty Fields
Date Tue, 05 Nov 2013 05:26:03 GMT
Or FieldValueFilter - that's probably easier to use.

> -----Original Message-----
> From: Michael McCandless [mailto:lucene@mikemccandless.com]
> Sent: Monday, November 04, 2013 4:37 AM
> To: Lucene Users
> Subject: Re: Lucene Empty Non-empty Fields
> 
> You can also use FieldCache.getDocsWithField?
> 
> Mike McCandless
> 
> http://blog.mikemccandless.com
> 
> 
> On Mon, Nov 4, 2013 at 7:33 AM, manoj raj <manojlucdbt@gmail.com> wrote:
> > I did some experiments for finding empty fields, But i want to know
> > whether there is any other better method. Have to reduce hard disk space.
> >
> >
> > Method 1: Add "NULL String" in empty fields
> >
> > We can search with null string for empty column & non empty column
> >
> >
> > Observations:
> >
> >    - Index size will grow.
> >    - Suppose if we add one new column, then old documents will not have
> >    null string  for that new column in index.
> >    - While fetching results, more IO will happen because of null string.
> >
> >
> > Method 2: Add one extra field namely NON_EMPTY_COLUMN and add all not
> > empty column names in that.
> > We can search like NON_EMPTY_COLUMN:Field_Name, for empty column
> > documents we have to search with Not of field name
> >
> > Observations:
> >
> >    - Again Index size will grow
> >    - Fetching is not costly
> >
> >
> > Method 3: While Searching, iterate through results and check for empty
> > column by using doc.get
> >
> > Observations:
> >
> >    - Iterations will become costly, suppose required results is not present
> >    in first set of results.
> >    - Also IO big impact in this.
> 
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