1. A method comprising: decomposing a search query that includes three or more words into a plurality of candidate phrasifications, each candidate phrasification having a different grouping of component phrases, a component phrase including a non-zero quantity of the words and each candidate phrasification including all of the words of the search query; scoring one or more candidate phrasifications, a candidate phrasification being scored by applying a scoring model, the scoring model based on a number of component phrases in the phrasification, a probability of occurrence of each of the component phrases in the candidate phrasification from a valid phrase table, and parameters for adjusting precision and recall of the candidate phrasification, the parameters including a first parameter to adjust precision of candidate phrasifications and a second parameter to adjust bias against obtaining too many phrases; selecting at least one highest scoring candidate phrasification; and executing the at least one highest scoring candidate phrasification against an index that includes posting lists for phrases, the executing identifying documents associated with each of the component phrases of the highest scoring candidate phrasification.
2. The method of claim 1 , further comprising generating, prior to scoring candidate phrasifications, at least one additional candidate phrasification by replacing at least one of the component phrases in a grouping with a related phrase.