With different threads calculate sum for specified database table column with specified filter and keep calculated amount in memory.

There is a need to create multithreaded task engine service, which can be managed
by sending xml messages with different parameters to the database. Service should
be implemented to run as fast as can and use memory as optimal as can. There are
examples of different tasks:
1. Generate randomly data for specified database table and with different threads to
write data to the table.
2. With different threads calculate sum for specified database table column with
specified filter and keep calculated amount in memory. Calculation should be
done in .net part by loading different parts of table in different threads.
3. Write calculated amount from memory to specified table and add additional
information – who and when performed calculation and what filter was used.