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From <karl.wri...@nokia.com>
Subject RE: Question about string retrieval with FieldCache in trunk
Date Wed, 18 Aug 2010 18:50:18 GMT
Ah, the old "switch that you shouldn't throw" trick. ;-)
Karl

-----Original Message-----
From: ext Michael McCandless [mailto:lucene@mikemccandless.com] 
Sent: Wednesday, August 18, 2010 2:39 PM
To: dev@lucene.apache.org
Subject: Re: Question about string retrieval with FieldCache in trunk

OK, that's good you got to the bottom of it.

This is (for better or worse) how FieldCache works.  It uninverts the
requested field to reconstruct the "forward" index (mapping docID ->
value), so the field must be indexed (and every field must have a
single token/value).

I agree it's odd... and there's work underway to add index values to
Lucene (called column-stride fields):

    https://issues.apache.org/jira/browse/LUCENE-2186

These would be directly stored in the index in "forward" index form.

Mike

On Wed, Aug 18, 2010 at 2:31 PM,  <karl.wright@nokia.com> wrote:
> This field was *not* indexed, just stored.  That seems to have been the problem.  Not
sure why it must be indexed to be retrievable, but clearly it does.
>
> Karl
>
> -----Original Message-----
> From: ext Michael McCandless [mailto:lucene@mikemccandless.com]
> Sent: Wednesday, August 18, 2010 2:28 PM
> To: dev@lucene.apache.org
> Subject: Re: Question about string retrieval with FieldCache in trunk
>
> Odd... the field is definitely indexed?  If you try getTermsIndex are
> they still empty?
>
> Are you just calling .utf8ToString() to get the String from the BytesRef?
>
> Mike
>
> On Wed, Aug 18, 2010 at 1:18 PM,  <karl.wright@nokia.com> wrote:
>> Thanks, didn't think to look there.
>>
>> Unfortunately I'm still getting back empty strings - and this is for a required field.
 So something isn't right...
>>
>> Maybe I'll pester Simon. ;-)
>> Karl
>>
>> -----Original Message-----
>> From: ext Michael McCandless [mailto:lucene@mikemccandless.com]
>> Sent: Wednesday, August 18, 2010 12:43 PM
>> To: dev@lucene.apache.org
>> Subject: Re: Question about string retrieval with FieldCache in trunk
>>
>> Also note that the MIGRATE.txt in the lucene subdir should cover this.
>>
>> Mike
>>
>> Sent from my iPad
>>
>> On Aug 18, 2010, at 11:26 AM, Jason Rutherglen <jason.rutherglen@gmail.com>
wrote:
>>
>>> Karl,
>>>
>>> I believe one may pass an empty BytesRef in, and the values will be
>>> set within the getTerm method.
>>>
>>> On Wed, Aug 18, 2010 at 8:18 AM,  <karl.wright@nokia.com> wrote:
>>>> Exactly. getTerms() returns a DocTerms, which has this:
>>>>
>>>>    /** The BytesRef argument must not be null; the method
>>>>     *  returns the same BytesRef, or an empty (length=0)
>>>>     *  BytesRef if the doc did not have this field or was
>>>>     *  deleted. */
>>>>    public abstract BytesRef getTerm(int docID, BytesRef ret);
>>>>
>>>> How in the blazes do you create the correct BytesRef in the first place?
 Or is the comment wrong?
>>>>
>>>> Karl
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: yseeley@gmail.com [mailto:yseeley@gmail.com] On Behalf Of ext Yonik
Seeley
>>>> Sent: Wednesday, August 18, 2010 10:55 AM
>>>> To: dev@lucene.apache.org
>>>> Subject: Re: Question about string retrieval with FieldCache in trunk
>>>>
>>>> Check out getTerms and getTermsIndex
>>>>
>>>> -Yonik
>>>> http://www.lucidimagination.com
>>>>
>>>> On Wed, Aug 18, 2010 at 10:49 AM,  <karl.wright@nokia.com> wrote:
>>>>> Hi folks,
>>>>>
>>>>> What is the proper way to retrieve a string field from lucene in trunk?
 I'm
>>>>> specifically looking for the equivalent of:
>>>>>
>>>>> String[] fieldValues = FieldCache.DEFAULT.getStrings(reader,fieldName);
>>>>> String actualValue = fieldValues[luceneID-docBase];
>>>>>
>>>>> The getStrings() method seems to have gone away in FieldCache.java, and
it's
>>>>> not clear how to work with ByteRefs to do the equivalent.  Any hints?
>>>>>
>>>>> Karl
>>>>>
>>>>>
>>>>>
>>>>
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>>>
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>
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