Distributed database system, method for building index therein and query method

The invention discloses a distributed database system and a method for building an index in the distributed database system. The distributed database system comprises a plurality of distributed storage units, an index memory, a resolver, an index query module and a parallel processing engine, wherein the distributed storage units store a plurality of data block files by sections; the index memory stores the indexes of the data block files; the resolver resolves a query sentence initiated by a user and selects a corresponding query index; the index query module searches the indexes of the data block files according to the selected query index to obtain at least one query data block set; the query data block set comprises an index key value and records the position information of the data block files corresponding to the index key value in the data block files; and the parallel processing engine splits the at least one query data block set and initiates a parallel scanning task.