We are looking into the network traffic between the Derby JDBC driver
and the Network server and have compared this against MySQL and
PostgreSQL. The main finding is that Derby sends more messages than
the two other databases.
For two simple transaction loads the following number of round-trips
between the client and server is done:
Derby MySQL PostgreSQL
----------------------------------------
"Select" 4 2 2
"TPC-B" 8 6 6
The "Select" load consists of one SELECT operation followed by a
commit. The "TPC-B" like load consists of five SQL operations (3
updates, 1 insert and 1 select) followed by a commit.
These numbers indicate that Derby needs two extra round-trips between
the client and the server per transaction. These extra round-trips add
to network traffic and to more CPU usage by the Network server. I
think it would be good for the Derby performance if we could get rid
of two of the message round-trips.
This experiment was done using the Derby JDBC client driver. We have
not (yet) tested using the IBM DB2 JDBC Universal driver.
..olav
