The APIs for creating a database (openDbi) don't take a transaction as input parameter (it's generated internally and immediately committed). This code works:

    Dbi<ByteBuffer> dbi = env.openDbi("TEST", new DbiFlags [] { DbiFlags.MDB_CREATE });    Txn<ByteBuffer> txn = renv.txnWrite();    dbi.put(txn, key, val);    txn.commit();

This code DOES NOT:

    Txn<ByteBuffer> txn = repoEnv.txnWrite();    Dbi<ByteBuffer> dbi = repoEnv.openDbi("TEST", new DbiFlags [] { DbiFlags.MDB_CREATE });    dbi.put(txn, key, val);    txn.commit();

by throwing this exception:

Exception in thread "main" org.lmdbjava.LmdbNativeException$ConstantDerivedException: Platform constant error code: EINVAL Invalid argument (22)
at org.lmdbjava.ResultCodeMapper.checkRc(ResultCodeMapper.java:114)
at org.lmdbjava.Dbi.put(Dbi.java:411)
at test.TestMain.main(TestMain.java:34)

This seems to be a blocking issue in a complex application where databases may be require to be created on-demand while a write transaction is already up and running. Or there is an alternative ? Please note that the native LMDB API for opening/creating a database do require a transaction., why not exposing it as parameter?