1. A method in a computing system for performing a pipelined search, comprising: (a) receiving a search query specifying a first processing command and a second processing command, the search query indicating that the first processing command precedes the second processing command; (b) accessing a plurality of timestamped events derived from machine data; (c) applying the first processing command to data from the accessed plurality of timestamped events to obtain a first result set; (d) associating with the first result set metadata generated by the application of the first processing command to data from the accessed plurality of timestamped events; (e) applying the second processing command to data from the first result set to obtain a second result set; and (f) associating with the second result set metadata generated by the application of the second processing command to data from the first result set.