(PECL sphinx >= 0.1.0)
SphinxClient::buildKeywords — Extract keywords from query
$query
   , string $index
   , bool $hits
   )
   Extracts keywords from query using tokenizer 
   settings for the given index, optionally with
   per-keyword occurrence statistics.
  
queryA query to extract keywords from.
indexAn index to get tokenizing settings and keyword occurrence statistics from.
hitsA boolean flag to enable/disable keyword statistics generation.
Returns an array of associative arrays with per-keyword information.