2. The method recited in claim 1 , further comprising: extracting from one or more logs one or more query sequences, wherein each query sequence comprises one or more queries received at a search engine ordered according to when the one or more queries are received at the search engine; constructing one or more query-suggestion pairs to be included in the set of query-suggestion pairs from each query sequence, wherein constructing one query-suggestion pair from one query sequence comprises: selecting from the one query sequence two queries; and constructing the one query-suggestion pair with a preceding one of the two queries as the query and a succeeding one of the two queries as the suggestion.
2. The method recited in claim 1 , further comprising: extracting from one or more logs one or more query sequences, wherein each query sequence comprises one or more queries received at a search engine ordered according to when the one or more queries are received at the search engine; constructing one or more query-suggestion pairs to be included in the set of query-suggestion pairs from each query sequence, wherein constructing one query-suggestion pair from one query sequence comprises: selecting from the one query sequence two queries; and constructing the one query-suggestion pair with a preceding one of the two queries as the query and a succeeding one of the two queries as the suggestion. 5. The method recited in claim 2 , further comprising: if an entity issues a same query multiple times to the search engine during a same day, then discarding duplicate instances of the same query of the same day when extracting the one or more query sequences; and if the entity issues a number of queries to the search engine during the same day that is greater than a predetermined query threshold, then discarding all search queries issued by the entity of the same day when extracting the one or more query sequences.