16. The method of claim 13 , wherein extracting the first set of keywords further includes: extracting a predetermined number of central words from the set of action logs associated with timestamps prior to the predetermined time point and assigning each central word to a priority level of level one; matching each central word against words in a product wordlist and assigning each central word that matches a word in the product wordlist a priority level of level two; matching each of those central words that matched a word in the product wordlist against bid words included in a bid wordlist and assigning each central word that matched a word in the product wordlist and also matches a word from the bid wordlist the priority level of level three; ranking the central words based at least in part on their respective priority levels; and determining that a predetermined number of central words associated with the highest priority level to be the first set of keywords.
13. A method for determining recommendation data, comprising: extracting a first set of keywords from a set of user action logs that occurred prior to a predetermined time point; extracting a second set of keywords from a set of user action logs that occurred subsequent to the predetermined time point; merging at least a portion of the first set of keywords and at least a portion of the second set of keywords to obtain a third set of keywords; matching, using one or more processors, at least one keyword in the third set of keywords with a database of data that can potentially be recommended to a user; and in the event that a piece of data in the database is determined to match the at least one keyword from the third set of keywords, determining that the piece of data is to be recommended to the user.