Hi,
I'm profiling H2 running my app's tests and have a few questions about
the hotspots, none of which are H2 implementation problems, but instead
just artifacts of my approach.
So, I'm using a named, in-memory database, e.g.:
JdbcConnectionPool.create("jdbc:h2:mem:foo", "", "");
The two big hotspots are:
1) Re-playing the 10+ Rails-style migrations that issue CREATE TABLE
commands to create foo's schema. Doing this once at the start takes
~1/4th of the test runtime.
2) Between each test, I flush the database so that each test has a clean
data set to work this. This looks like:
for (Alias<?> a : Copy.reverse(AliasRegistry.getAliasesSorted())) {
Jdbc.update(Registry.getDataSource(), "DELETE FROM {}",
Wrap.quotes(a.getTableName()));
if (a.isRootClass()) {
Jdbc.update(Registry.getDataSource(), "ALTER SEQUENCE {}
RESTART WITH 1 INCREMENT BY 1;", a.getTableName() + "_id_seq");
}
}
With 70 tests, this flush happens 70 times, but 30 tables, that is ~2100 DELETE
FROMs. Each individual one is quick, but in aggregate, all 2100 take roughly
~1/2th of the test runtime.
In postgres, I ended up generating a "flush_test_database" stored procedure
that had all of the DELETEs in it, which meant just one JDBC call and that
really helped perf; but from the H2 stored procedure stuff I've seen, I'd
been using JDBC anyway. Some sort of global "delete all" would be cool,
though granted only useful for dev/test environments.
So, if I could solve these two problems--quickly bootstrapping an in-memory
database with an existing schema (I've seen the backup zip files and will
try that next--I wasn't sure if I could backup/load in-memory databases),
and then flushing all of the data in each setUp, I'd cut my test runtime
by 3/4ths. Which would be great.
If anyone has any tips or tricks, I'd really appreciate it.
Thanks,
Stephen
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