[Solr Wiki] Update of "SchemaDesign" by YonikSeeley

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The following page has been changed by YonikSeeley:
http://wiki.apache.org/solr/SchemaDesign

The comment on the change is:
sorting is not slower on a non-integer field, clarify stemming

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  = Sorting =
  There are two ways of sorting available in Solr 1.4: Lucene's sorting feature and function queries.
  == Lucene Sorting ==
- The Solr sort parameter uses the Lucene sorting tool. This creates an array containing an entry for every document in the index using the !FieldCache. Sorting is then done against this array. This array is cached across requests using the !IndexReader and so repeated sorts are fast.  If the field type is 'integer' the array contains only that value and thus is 4 bytes * the number of documents. If the field type is anything else, this integer array is created and then a separate array is also created with that field's data per entry. Sorting is also slower if the type is not an 'integer'.
+ The Solr sort parameter uses the Lucene sorting tool. This creates an array containing an entry for every document in the index using the !FieldCache. Sorting is then done against this array. This array is cached across requests using the !IndexReader and so repeated sorts are fast.  If the field type is 'integer' the array contains only that value and thus is 4 bytes * the number of documents. If the field type is anything else, this integer array is created and then a separate array is also created with that field's data per entry.
- However, range checks do not work on an 'integer' field. If you want range checks and fast sorting, you can create a pair of fields, one of each type, with a copyField directive:
- {{{
-  <field name="popularity" type="sint" indexed="true" stored="true" multiValued="false"/>
-  <field name="popularitySort" type="integer" indexed="true" stored="false" />
-  ...
-  <copyField source="popularity" dest="popularitySort"/>
- }}}
- Note that since multiValued=false is the default for these types, attempting to store a value to 'popularitySort' will cause an indexing error, since it also always receives a value from 'popularity'. Also there is no reason to store both fields, and so 'popularitySort' is index-only.
  
  === A Note on "sortable" FieldTypes ===
  Sortable !FieldTypes like sint, sdouble are a bit of a misnomer.  They are not needed for Sorting in the sense described above, but are needed when doing !RangeQuery queries.  Sortables, in fact, refer to the notion of making the number sort correctly lexicographically as Strings.  That is, if this is not done, the numbers 1..10 sort lexicographically as 1,10, 2, 3...  Using an sint, however remedies this.  If, however, you don't need to do !RangeQuery queries and only need to sort on the field, then just use an int or double or the equivalent appropriate class.  You will save yourself time and memory.
@@ -28, +20 @@

  }}}
  There may be performance differences with this technique v.s. the Lucene sorting algorithm.
  = Multiple Text Search Field types =
- The "text" field type in the example schema.xml provides basic text search for English text. But, it has a surprise: the actual text given to this field is not indexed as-is, and therefore searching for the raw text may not work. If you store "To Be Or Not To Be" in a "text" field, none of these words will found this document, nor will the phrase in quotes. The above words are all ''stopwords'' and are stripped from the input text. Another transform is ''stemming'', which stores both 'change' and 'changing' as the word 'chang'.
+ The "text" field type in the example schema.xml provides basic text search for English text. But, it has a surprise: the actual text given to this field is not indexed as-is, and therefore searching for the raw text may not work. If you store "To Be Or Not To Be" in a "text" field, none of these words will found this document, nor will the phrase in quotes. The above words are all ''stopwords'' and are stripped from the input text. Another transform is ''stemming'', which stores both 'change' and 'changing' as the word 'chang'.  Stemming is done at both index and query time, so a query of 'changing' will match a document containing 'change'.
  == Phrase search ==
  If you want to have any phrase search work as well as individual words, you need to have two fields. Both should be processed similarly, but the phrase search field should not use stemming or stopwords. 
  == Phonemes ==