The embodiment of the invention provides a
distributed database system, which comprises storage nodes, an
access control device and an unloading device, wherein the
access control device is used for receiving access requests, extracting
record identifiers from the access requests, searching for the storage nodes corresponding to the
record identifiers from a storage comparison table, updating the accessing times of
data records with the
record identifiers, acquiring the corresponding
data records from the storage nodes according to the record identifiers, and returning the acquired
data records; and the unloading device is used for determining the accessing times according to the accessing times of each data record corresponding to the storage nodes in the storage comparison table, and when determining the storage nodes are overloaded according to the accessing times of the storage nodes by using a preset pressure
algorithm, selecting the data records from the plurality of data records of the storage nodes according to a preset unloading strategy, unloading the selected data records into the other storage nodes which are not overloaded, and updating the storage comparison table. The invention also provides a data accessing method. The embodiment of the invention can satisfy the needs of real-
time data accessing operation.