To sort data items in a spreadsheet table, data items in the spreadsheet table are divided into a plurality of blocks. Multiple threads are used to sort the data items in the blocks. After the data items in the blocks are sorted, multiple merge threads are used to generate a final result block. The final result block contains each of the data items in the spreadsheet table. Each of the merge threads is a thread that merges two source blocks to generate a result block. Each of the source blocks is either one of the sorted blocks or one of the result blocks generated by another one of the merge threads. A sorted version of the spreadsheet table is then displayed. The data items in the sorted version of the spreadsheet table are ordered according to an order of the data items in the final result block.