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Java Forum / General / August 2007Migrating project from MySQL to embedded, relational Java-Database
Hi, I want to migrate a project that is based on MySQL, to a different, relational, Java-embedded Database (non-commercial, if possible). "Apache Derby" was my first idea. As usual, it will not be as easy as it could be (e.g., I heard, that Derby does not allow an unique index on columns that may be null, whereas MySQL has no problem with that). My research with google gave the following projects: - HSQL (http://hsqldb.sourceforge.net/) Seems to be active and praises itself to be used in OpenOffice, which seems to look good. - H2 (http://www.h2database.com/html/frame.html) The hompage does not look too professional at first glance, but at second glance it looks better... - One$DB (http://daffodildb.com/one-dollar-db.html) (Free, open source version of DaffodilDB, see below. The name only suggests, that the support is 1$ per day.) I must say, that my evaluation has just started and that I did not really test one of the projects. Below, there are some projects which I rejected at first glance (perhaps too fast). (*) So, my questions are: Are there any other promising projects I did not realize (or rejected hastily)? Did anybody use one of these projects? Which experiences have you made with migrating applications to different databases (especially from MySQL)? Bye, Ingo (*) rejected at first: - db4o (http://www.db4o.com/) Object-oriented. SQL only per special module, AFAICS. - Oracle Berkley DB Java Edition (http://www.oracle.com/database/berkeley-db/je/index.html) Problematic license. - Axion (http://axion.tigris.org/) Last acitvity 7'2003 - tinySQL (http://www.jepstone.net/tinySQL/) Looks really half-baked (many features missing). - SmallSQL (http://www.smallsql.de/) commercial: http://www.smallsql.de/faq-general.html - Quadcup QED (http://www.quadcap.com/home.html) commercial - ozone (http://www.ozone-db.org/frames/home/what.html) Objekt-oriented, not relational! - DaffodilDB (http://www.daffodildb.com/embeddeddatabase.html) commercial - Mckoi (http://www.mckoi.com/database/) Last activity 8'2004 (is that correct?) - Ashpool (http://robrohan.com/projects/ashpool/) Project ceased 9'2006 - BlockFile (http://www.metanotion.net/software/sandbox/block.html) Designed for PDA, J2ME. Very small solution (no transactionen, SQL and JDBC!) Hello, > I want to migrate a project that is based on MySQL, to a different, > relational, Java-embedded Database (non-commercial, if possible). > "Apache Derby" was my first idea. From all I have seen so far, this would be my choice - especially because of the backing community which products like HSQL and H2 lack (mostly driven by a single developer) > As usual, it will not be as easy as it could be (e.g., I heard, that > Derby does not allow an unique index on columns that may be null, > whereas MySQL has no problem with that). Not sure what you mean with "does not allow". You can create an index on columns that allow null, but it won't allow to insert the same combination more than once. E.g. ('A', null) will not allowed twice which is e.g. the same way as Oracle handles this. Postgres seems to go the MySQL way and will allow multiple records with the same "values". This is - according to the Postgres manual - compliant with the ANSI standard. > - HSQL (http://hsqldb.sourceforge.net/) > Seems to be active and praises itself to be used in OpenOffice, which > seems to look good. Actually there isn't that much activity on that project. But the maintainer said that 1.9 is due this year. Following the forum on the sourceforge site and the mailing list, for my personal taste there are too many posts with the topic "Lost my data because...". My experience (though not in a real-world production system) it is nice for moderately sized databases but when the data starts to grow (Millions of rows) it does not scale very well. > - H2 (http://www.h2database.com/html/frame.html) > The hompage does not look too professional at first glance, but at > second glance it looks better... It does look promising and it sure has (currently) more momentum than HSQL. But taking into account that it is relatively new, I would be reluctant to use it in a production system. Regards Thomas Hi Thomas, Thank you very much for your feedback! But some more questions...: >... > because of the backing community which products like HSQL and H2 lack > (mostly driven by a single developer) Where do you get that from? >> As usual, it will not be as easy as it could be (e.g., I heard, that >> Derby does not allow an unique index on columns that may be null, [quoted text clipped - 8 lines] > the same "values". This is - according to the Postgres manual - > compliant with the ANSI standard. Do you know if there are any flags or environment variables that allow to change the behaviour of Derby in this context? >> - HSQL (http://hsqldb.sourceforge.net/) >> Seems to be active and praises itself to be used in OpenOffice, which >> seems to look good. > > Actually there isn't that much activity on that project. Latest news are from 28 July 2007. Sourceforge says: 34 Developers. Ah, OK, I see: most current build from September 27, 2006, nearly one year. OK, indeed... > But the > maintainer said that 1.9 is due this year. Following the forum on the > sourceforge site and the mailing list, for my personal taste there are > too many posts with the topic "Lost my data because...". Uh-oh! >> - H2 (http://www.h2database.com/html/frame.html) >> The hompage does not look too professional at first glance, but at [quoted text clipped - 3 lines] > HSQL. But taking into account that it is relatively new, I would be > reluctant to use it in a production system. Yes, the curent version is 1.0! I did not realize that at first sight! Bye, Ingo >> because of the backing community which products like HSQL and H2 lack >> (mostly driven by a single developer) > > Where do you get that from? Judging from the Google Groups for H2 the main developr of H2 is Thomas Müller (btw: the original brain behind hsqldb as well): <http://groups.google.com/group/h2-database/browse_frm/thread/2a9f146ab56b3778/47 f86f2f5fa7e605#47f86f2f5fa7e605> Taking the participation from the sourceforge groups for hsqldb, I'd say there are two main developers for hsqldb: Fredt Toussi (who is the maintainer as far as I know) and Campbell Boucher-Burnet. But I might be mistaken with that. As I said: that is my personal perception of the discussions in the forum. I have been monitoring the Apache Derby mailing list as well, and my imporession was that the team behind that is a bit bigger, and the wiki pages http://wiki.apache.org/db-derby/DerbyFaces seem to support my assumption. >>Following the forum on the sourceforge site and the mailing list, for my >>personal taste there are too many posts with the topic "Lost my data because...". > Uh-oh! Looking at a forum is usually a single-sided viewpoint, because only people with problems participate, so I don't know how many out there don't actually have problems. Taking the popularity of hsqldb into account those people with problems are probably a very small percentage, but still for my personal taste there are a bit too many posts in that direction. Some of those problems are easily solved by reading the documentation carefully though. > Do you know if there are any flags or environment variables that > allow to change the behaviour of Derby in this context? No idea (mostly because I prefer Derby's/Oracle's implementation) but you might want to ask that on the mailing list which is mirrored on news.gmane.org (regular newsreader access) Regards Thomas Hi Thomas, thanks again for your quick feedback. That all leads me to your first sentence in this thread: "From all I have seen so far, this (Apache Derby) would be my choice." 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