public static DBAccessor create() {
if(dbAccessor != null)
return dbAccessor;
final DBAccessor dba;
if(KIND_POSTGRES.equals(DB_KIND)) {
dba = new PGAccessor();
} else if(KIND_DERBY.equals(DB_KIND)) {
dba = new DerbyAccessor();
} else {
throw new UnsupportedOperationException("Unsupported DB kind: " + DB_KIND);
}