More on Java DBs comparison
Following a comment from Alexandre on a previous post, I went a little bit further with my performance test of database engines running under Java. This evening, I tested a profiling tool and a variable number of insertions/retrievals (I didn’t tested transaction).
Taking the code from the previous time, I simply changed the number of elements to be inserted/retrieved. As expected, the durations of object initialization (except for 2 points for Derby and H2) and database creation did not change with the number of elements to be inserted, Derby being still the slowest engine to create a simple database (1 table only). The durations of the insertion step increased slowly with all the database engine, except for SQLite+JDBC: you can see a much steeper initial angle in the increase of the duration in the graph below (be careful: x-axis shows logarithmic values).
For the retrieval, all the engines increased their time spent in this step in the same way (approximately). All the graphs can be seen here.
Performance analysis was completed using a free profiling tool, jRat (list of tools available here and here). There is a big difference here since jRat measures the time spent in each function. These functions approximately match the previous “steps” but not exactly. And I had memory problems using jRat with a number of elements inserted > 100 (hence the limit here).
Derby and SQLite+JDBC always performed worst than other engines (except for the
showData() function). Usually, H2 and HSQLDB had more stable results (smaller standard deviations). And SQLite+JDBC was still the worst engine regarding data insertion (see graph below).
It was also very strange to see that H2 and HSQLDB took approximately the same time to insert 100 or 1000 elements (note that for HSQLDB, I did not take into account the fact one needs to explicitly close the connection, allowing HSQLDB to temporarily store data in memory before committing them to the file -- but closing the connection didn't take so much time). All the graphs can be seen here.
One conclusion of all this: if you write a Java application and need a fast Java database engine, use HSQLDB (BSD-like license) or H2 (modified MPL). Next time, I'll test transactions (but I don't know when it'll be).