http://sphinxsearch.com/forum/view.html?id=9540 Fields are full-text indexed - suitable for searching
Attributes are stored as is - and so useful for sorting/grouping and even getting the information out.
http://sphinxsearch.com/forum/view.html?id=5440
... UNIX_TIMESTAMP(Document.dateFiled) as dateFiled, ... Converts it to a unix timestamp - Good!
sql_attr_timestamp = dateFiled Makes it an attribute - also Good!
http://sphinxsearch.com/docs/current/conf-sql-attr-timestamp.html Note that DATE or DATETIME column types in MySQL can not be directly used as timestamp attributes in Sphinx; you need to explicitly convert such columns using UNIX_TIMESTAMP function (if data is in range).
http://sphinxsearch.com/docs/current/conf-sql-attr-string.html string not indexed - token?
http://sphinxsearch.com/docs/current/conf-sql-field-string.html - this allows full text search
MVA http://sphinxsearch.com/docs/current/conf-sql-attr-multi.html http://sphinxsearch.com/forum/view.html?id=9158 sql_attr_multi = uint categories from query; SELECT entry_id, cat_id FROM exp_category_posts