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From testn <te...@doramail.com>
Subject Re: Search for null
Date Tue, 24 Jul 2007 13:26:52 GMT

Would it be more efficient to create an additional inverted field where I
assign a value to that field only when the field I would like to search is
NULL?


daniel rosher wrote:
> 
> Perhaps you can use a filter in the following way.
> 
> -Create a filter (via QueryFilter) that would contain all document that
> do not have null values for the field
> -flip the bits of the filter so that it now contains documents that have
> null values for a field
> -Use the filter in conjunction with subsequent queries.
> 
> This would also help with performance as filters are simply bitsets and
> can cheaply be stored, generated once and used often.
> 
> Dan
> 
> On Mon, 2007-07-23 at 13:57 -0700, Jay Yu wrote:
>> If you want performance, a better way might be to assign some special 
>> string/value (if it's easy to create) to the missing field of docs and 
>> index the field without tokenizing it. Then you may search for that 
>> special value to find the docs.
>> 
>> Jay
>> 
>> Les Fletcher wrote:
>> > Does this particular range query have any significant performance
>> issues?
>> > 
>> > Les
>> > 
>> > Erik Hatcher wrote:
>> >>
>> >> On Jul 23, 2007, at 11:32 AM, testn wrote:
>> >>> Is it possible to search for the document that specified field 
>> >>> doesn't exist
>> >>> or such field value is null?
>> >>
>> >> This is from Solr, so I'm not sure off the top of my head if this mojo 
>> >> applies by itself, but a search for -fieldname:[* TO *] will result in 
>> >> all documents that do not have the specified field.
>> >>
>> >>     Erik
>> >>
>> >>
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> Daniel Rosher
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