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Small footprint embedded Java SQL database

I'm looking for an embedded SQL database for Java, with a small footprint. Something like SQLite, but it should be pure Java. So far I've seen HSQLDB, H2 and Apache Derby, but they're not what could be called small footprint. Ideally, the database I'm looking for would be embeddable in a J2ME application.
Is there something like this?

Take a look at HSQLDB or H2DB
or possibly a light key value based database like jdbm2

Yes, there is an Apache project for that called Apache Derby.

You may try http://www.jepstone.net/tinySQL/.
Pros:
It is small (93k!)
It is embeddable
It uses DBF or text files files to store data, so they are easy to read.
Cons:
It is an old unmaintained project
It is not designed to work in j2me, but since it can work in JDK 1.1.8 it won't be hard to make it work in j2me. Of course you will have to change some code from using RandomAccessFile to FileConnection and stuff like that, but at least you wont need to mess with generics related code.
It is not very fast, because it does not use indexes, so you need to try and see if it is fits yuor needs
It is not feature complete, just gives you a small subset of SQL

You can also look at:
Floggy - http://floggy.sourceforge.net/
Perts Lite - http://www.mcobject.com/j2me_database/
J2MEMicroDB - http://morfeo.upc.es/crom/mod/wiki/view.php?id=16&page=Qu%E8+%E9s+J2MELSDATALIB&gid=0&uid=0
HandyDB - http://sourceforge.net/projects/rms-db-class/
MicroDB - http://sourceforge.net/projects/microdb/
OpenBaseMovil - http://www.openbasemovil.org/2007/11/26/openbasemovil-portable-j2me-database-applications/
This list is something I just found on the internet (http://www.coderanch.com/t/230853/JME/Mobile/List-Database-ME) and some of the listed products seems abandoned, but I thought that maybe it can be helpful...

Performance Testing Various Databases

I am currently testing a few different relational database management systems. (MySQL, PostgreSQL, Oracle and Firebird SQL) using a Java application to do so.
I was debating what tests I should run to distinguish the performances of each.
The obvious ones would be insert, select, delete and drop.
I would love to hear your opinions and to make this apply to the question answer format I shall ask for the 5 most appropriate tests to indicate performace differences. In an ideal world I would like to mimic real word use.
Thanks to all who answer.

I think that any of them would probably be fine. However, your configuration of the different databases for what you are trying to do would be different based on your application.
Suggested place to start: look for apps similar to yours. See what they are using, if you can. Then start testing the different databases with similar configurations and see what works for you.
Personally I've used Oracle, MySql, and Postgres over the last 11 years and they've all worked well. It's really all in your configuration, which is where a good DBA comes in handy.

Here are the results of a fairly extensive benchmarks of JPA providers and RDBMS's. You can either use the data they provide, or you can download their code and run it yourself.

Test concurrency. In other words, what happens under various locking scenarios? Ideally you would like to test under as close to real world conditions as possible, with multiple users using the system as it was meant to be used. See my answer to this SO question.

Need for Hibernate in the legacy world [closed]

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I have a several questions about hibernate.
In many questions here in stackoverflow, several people are saying that hibernate is not a good choise for very complex databases. If we have very complex database, hibernate is not the right choice. It better suits for green field projects, but it is not so good for complex legacy database.
Is this true?
Also hibernate generates queries.
Every project manager will like to have optimized queries (hibernate cannot generate more optimized queries than sql specialist!). So for big project it is not a problem to hire sql specialist. The sql specialist will optimize the queries (use explain sql, use joins ...)
My question is how come a huge and expensive project does not care about sql optimization?
(you will say that you can write HQL but as I have seen in a lot of posts that explains that HQL is not so powerful than sql and a lot of programmers get headache and several hours of tuning) (you like all your organs in your body to work ideally don't you?)
Also the second level cache helps hibernate a lot because hibernate knows to generate a lot of queries instead of complex join.
My question is: Is really a complex db only modified by one system (example the web site)? If we are talking about the enterprise system the db can be accessed via several processes, sharing different programming languages and platforms.
So in this case the second level cache does not help very much.
For what kind of projects hibernate is suitable for?
Is it for back office projects where nobody cares about the sql ?
What happens when your administrator says: please use memcached for caching and please use this optimized queries instead of yours?
If you are using oracle database, orache has the most advanced sql syntax. They have spend a lot of time and money on the syntax that is very powerful. What for is this syntax if it is not used.
The software is written only once (and then maintained) and used for a long time.
If I am a company that orders software I will say: I will use the software for a couple of years and I like to be fast, and if you spend 1 month for writing software with hibernate I will pay one more month for software that uses example IBATIS knowing that it will work better for years
(when you are buying a car you are interested in the car economy 1kg-oil/km, not how short and easy the manufacturer produced the car!). So as a software consumer I do not interested in your productivity, just how fast the software is. Of course also the price is relevant but if we are speaking about the price there are more complex mathematics.
Can we call something engineering when we really cannot predict some part of the system?
(can electrical engineer be really a engineer if he cannot predict the current)
Please share your opinion.
Regards

1) (...) Is this true?
No it isn't, Hibernate can deal with pretty complex databases, including existing ones. However, it might not deal very well with an heavily denormalized database or an exotic schema. This is different.
2) (...) My question is how come a huge and expensive project does not care about sql optimization?
This is non-sense, using Hibernate doesn't mean you don't care about optimization. I have worked on a huge and complex STP system (several hundreds millions € budget) and performance was definitely an important concern and we actually introduced Hibernate to benefit from things like lazy loading, second level cache (and speed up development).
Here is the deal when using an ORM like Hibernate (when suitable):
You'll be done faster with ORM than without ORM (or there wouldn't be any point at using them).
The vast majority of the generated queries will behave correctly (and the fact is that Hibernate generates better SQL than the average developer).
You can (and have to) tune queries and Hibernate to a certain degree.
Even if you spend some time on performance optimization (including falling back to native SQL for really problematic queries), you'll still be done faster.
3) (...) So in this case the second level cache does not help very much.
Well, you are right about the fact that using the second level cache ideally means using Hibernate APIs (although you can still evict the cache "manually" and although I tend to prefer using it for "mostly read" entities). But, more important, to my experience sharing data between many applications through the database just leads to unmaintainable applications (changing a single bit becomes impossible as it may impact several applications) and and should be avoided. Use an EAI/ESB and expose services of the main system through it. This way, you can reuse the business logic, the 2nd level cache, etc.
4) (...) For what kind of projects hibernate is suitable for? Is it for back office projects where nobody cares about the sql ?
Hibernate is indeed very nice for CRUD applications, but not only (see above) and your question shows some ignorance as I already said. However, it isn't suitable for any project:
I would probably not use it for a data warehouse or a big reporting application.
I might not use it with a heavily denormalized or exotic legacy database (a data mapper like mybatis might be a better choice in this case).
I might not use it with an existing system using stored procedure for everything.
I would not use it with a non RDBMS datastore :)
5) (...) What happens when your administrator says: please use memcached for caching and please use this optimized queries instead of yours?
I tell him that memcached is maybe not the best solution in our context (no, I don't want to always send my data over the wire and I don't care that Facebook/LiveJournal/Twitter/whatever are using it, our app might have different needs), there are other better cache implementations when working with Hibernate, I ask him to discuss problems with me and we discuss the various solutions, etc. We work as a team, not against each other.
To sum up, ORM solutions are not always suitable but I think that you currently have a biased opinion and my experience is different from the opinions (misbeliefs?) expressed in your question.
See also
When NOT to use O/R mapping in Java

It's good for green field projects, but it's also good for legacy projects. You may need to do some mapping tricks, but it offers reasonably flexible mapping.
Since you can use native queries, and since you can integrate it with your favorite caching solution, you don't need to suffer any performance problems just because you're using Hibernate. When your db administrator says that you should use memcached, you can use this memcached/Hibernate integration. You can write a caching implementation using your favorite cache and plug in into Hibernate. When she says you should use this optimized query, you say "great! Hibernate has a native SQL facility that will let me use that query". You can use native Oracle syntax, you can use the native syntax of whatever RDBMS you've chosen.
A multiple-application environment poses the same challenges to Hibernate as it does to any solution. If you want your application to perform well, you will use what amounts to a second-level cache. Hibernate happens to offer an ORM that is integrated with the cache. It doesn't solve the problem of coordinating a cache across multiple applications, but you'll have to solve that problem even if you don't use Hibernate.

Your question is probably too broad. I can tell you about my experience.
I worked on a project that adopted the .NET version (NHibernate). A naive implementation of loading a single row from a single table was almost two orders of magnitude slower than a raw ADO query. After much optimization I believe they got it down to merely one order of magnitude slower.
In java where the start up time is probably less of a factor. The web server loads java and hibernate at server start instead of while a user waits for a desktop app to start.
Personally I really dislike it. It hides implementation details that are necessary to efficiently manage your data. I've found no real world application that could perform acceptably with a vanilla implementation of a data layer that hides database details.
But that may be sour grapes on my part since I was forced to use it and blamed for
not being able to put enough lipstick on the pig.

No matter how complex database is. The most important question is how complex domain model of application is.
Is query select * from anytable where anycol = #anyvalue optimized? I have no idea. Nobody has. Because there is only one true criteria of optimization - this is performance of such queries. You can save a lot of time with hibernate or other ORM, then use this time to find actually slow queries. As far as I know Hibernate has some ways to use optimized query.
Third your question is good. But also there is no one answer to the question 'Is dirty data good every time everywhere?'. Strictly saying, until locked, any data read from database are dirty, no matter how its were read and where its were stored. Data blocking is not good thing for performance, so usually you should find compromisse between actual data and performance.
There is no silver bullet. ORM has a lot of advantages, but there is only one serious case when it is not suitable: it is dynamic resultsets depends of parameters (when different parameters returns data with different column sets). Because object structure are static at compile time (in static typed languages) ORM can't help in this case.
Every other case can be solved. Entity sevices (changes tracking etc.) can be off, second-level cache can be disabled, and optimized query can be used instead of generated. I have no idea how to do all that things in Hibernate, but I'm sure it is possible.
ORM has a great advantage it concentrate all data access logic in manageable form, and put it in specific place. Also it supports few things are not so easy and direct to implement in your own data access library, like transaction management (including nested transactions, etc), identity mapping (one row - one object), complex hierarchy persisting (if you use objects and object hierarchies), optimistic locking etc, and ORM can greatly helps you with it.

Web framework for an application utilizing existing database?

A legacy web application written using PHP and utilizing MySql database needs to be rewritten completely. However, the existing database structure must not be changed at all.
I'm looking for suggestions on which framework would be most suitable for this task? Language candidates are Python, PHP, Ruby and Java.
According to many sources it might be challenging to utilize rails effectively with existing database. Also I have not found a way to automatically generate models out of the database.
With Django it's very easy to generate models automatically. However I'd appreciate first hand experience on its suitability to work with legacy DBs. The database in question contains all kinds of primary keys, including lots of composite keys.
Also I appreciate suggestions of other frameworks worth considering.

Use sqlalchemy. On any framework you choose. It can reflect your database as ORM.

I’m currently rebuilding a legacy PHP web application with a MySQL database my self.
The PHP code was kind of spaghetti and is now rewritten in Java as it type safe, promotes well-structured code, has excellent tooling and has superior unit testing capabilities. For database to Java mapping I use Hibernate/JPA.
The web application is incrementally delivered to production. Meaning we run both Java and large parts of the old PHP code together until the application is fully converted.
But in order to use hibernate effectively we needs the database to be logical correct (something MySQL MyIsam does not enforce). So with each production release I run an refactoring scripts for the database (also used to build the development environment and do unit testing) and update the PHP code with a new version that works with the schema changes.
As a web framework I use Stripes as it’s simple, elegant and easy to learn.

I have very good experience with Django. Every time I needed it was up to the task for interfacing with existing database.
Autogenerated models are the start, as MySQL is not the strictest with its schema. Not that it will not work only that usually some of the db restrictions are held in app itself.

My first thought would be to use Hibernate and Java, but I may be biased because that is what my experience is in. You generally map your Model classes via Hibernate after you create the database anyway, so it might not be a bad choice.
I'll let it explain itself to you: Hibernate's website

I suppose that any PHP Framework (I'm a PHP guy, so I will only talk about PHP) could be OK for you ; but you should use one that's well-supported, has a large community, ...
To make things short, I'm thinking about one off this list :
Symfony
Zend Framework
CakePHP
Kohana
Code Igniter
Now, if you're asking "which framework is the best", it's a question that doesn't really have an answer : it's mainly a matter of personnal preferences...
Still, here's a couple of questions+answers that could bring you some interesting informations :
Best PHP framework for an experienced PHP developer?
What PHP framework would you choose for a new application and why?
To use a PHP framework or not?
PHP Framework Decision - Analysis paralysis!
PHP - MVC framework?
Which PHP Framework is right for this project?
Also, note that choosing a Framework is an important decision -- which means you should take some time to evaluate each framework and how it'll answer your specific need.
Really : you should definitely not rush that decision.

You know, there's a whole Ruby web dev world away from Rails, e.g.:
Sinatra
Ramaze
Webby
With such a general question it's always a bit hard to help...

Try web2py, extremely easy to prototype any webapp, and IMO a bit easier to grasp (overall) than other similar web frameworks, HTH

There are no clear cut winners when picking a web framework. Each platform you mentioned has its benefits and drawbacks (cost of hardware, professional support, community support, etc.). Depending on your time table, project requirements, and available hardware resources you are probably going to need some different answers.Personally, I would start your investigation with a platform where you and your team are most experienced.
Like many of the other posters I can only speak to what I'm actively using now, and in my case it is Java. If Java seems to match your projects requirements, you probably want to go with one of the newer frameworks with an active community. Currently Spring Web MVC, Struts2, and Stripes seem to be fairly popular. These frameworks are mostly, if not totally, independent of the persistence layer, but all integrate well with technologies like hibernate and jpa; although you have to do most, if not all, of the wiring yourself.
If you want to take the Java road there are also pre-built application stacks that take care of most of wiring issues for you. For an example you might want to look at Matt Raible's AppFuse. He has built an extensible starter application with many permutations of popular java technologies.
If you are interested in the JVM as a platform, you may also want to look at complete stack solutions like Grails, or tools that help you build your stack quickly like Spring Roo.
Almost all of the full stack solutions I've seen allow for integration with a legacy database schema. As long as your database is well designed, you should be able to map your tables. The mention of composite keys kind of scares me, but depending on your persistence technology this may or may not be an issue. Hibernate in Java/.NET supports mapping to composite keys, as does GORM in grails (built on hibernate). In almost all cases these mappings are discouraged, but people who build persistence frameworks know you can't always scorch earth and completely recreate your model.

Java Embedded Databases Comparison [closed]

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I intend to develop a small (Java) application for managing my finances. I believe I need to use an embedded database, but I have no experience regarding this issue. I tried to look at some of the available products, but I can't decide which one would be more suitable for me. H2, HSQLDB, Derby and Berkeley DB seem to be good candidates, but I still don't see how they compare to each other. I appreciate your help comparing them and helping me decide which one to use.
I intend to use Hibernate for my application (unless you would recommend using DBMS-provided API), but I also want to have the ability to edit the database easily using a SQL browsing tool (modifying schema and changing data).
Thank you.

Either
HSQLDB - Used by OpenOffice, tested and stable. It's easy to use. If you want to edit your db-data, you can just open the file and edit the insert statements.
or
H2 - Said to be faster (by the developer, who originally designed hsqldb, too)
Which one you use is up to you, depending how much performance and how much stability you need.
The developer of H2 has put up a nice performance evaluation:
http://www.h2database.com/html/performance.html

I use Apache Derby for pretty much all of my embedded database needs. You can also use Sun's Java DB that is based on Derby but the latest version of Derby is much newer. It supports a lot of options that commercial, native databases support but is much smaller and easier to embed. I've had some database tables with more than a million records with no issues.
I used to use HSQLDB and Hypersonic about 3 years ago. It has some major performance issues at the time and I switch to Derby from it because of those issues. Derby has been solid even when it was in incubator at Apache.

I needed to use Java embedded database in one of my projects and I did lot of research understanding pros and cons of each database. I wrote a blog listing pros and cons of popular embedded java databases (H2, HSQLDB, Derby, ObjectDB, Neo4j, OrientDB), you can have a look at it. I chose H2 as I thought it best suited my requirements.
Link for the blog: http://sayrohan.blogspot.in/2012/12/choosing-light-weight-java-database.html
Hope it helps!

I'd go with H2, the performance is meant to much better than Derby. Read http://www.h2database.com/html/performance.html for more info.

HSQLDB is a good candidate (the fact that it is used in OpenOffice may convinced some of you), but for such a small personnal application, why not using an object database (instead of a classic relationnal database) ?
I used DB4O in one of my projects, and I'm very satisfied with it. Being object-oriented, you don't need the whole Hibernate layer, and can directly insert/update/delete/query objects ! Moreover, you don't need to worry about the schema, you directly work with the objects and DB4O does the rest !
I agree that it may take some time to get used to this new type of database, but check the DB40 tutorial to see how easy it makes working with the DB !
EDIT: As said in the comments, DB4O handles automatically the newer versions of the classes. Moreover, a tool for browsing and updating the database outside of the application is available here : http://code.google.com/p/db4o-om/

Java DB (Sun's distribution of Apache Derby) now ships in JDK 6!
I've been wanted to do something like Jason Cohen and have been thinking this looks like the easiest way being in the JDK distro (which of last week is now a requirement for my app). Or maybe I am just lazy that way.

We use HSQLDB in production as a "no-configuration" option for our application. It allows people to trial without the hassle of setting up a real database.
However we do not support it for normal use. The reasons are several:
Slows down proportionally to the size of the data.
Difficult to access outside of our app (e.g. for custom reports).
Transactions / disk-sync is difficult to get right, so it's easy to lose data.
For at least (2) and (3), there are ways around it but it's difficult; it's much easier to e.g. install MySQL.

neo4j is:
an embedded, disk-based, fully transactional Java persistence engine that stores data structured in graphs rather than in tables
I haven't had a chance to try it yet - but it looks very promising. Note this is not an SQL database - your object graph is persisted for you - so it might not be appropriate for your existing app.

HSQLDB may cause problems for large applications, its not quite that stable.
The best I've heard (not first hand experience however) is berkleyDB. But unless you opensource it, it will cost you an arm and a leg to use due to licensing...see this http://www.oracle.com/technology/software/products/berkeley-db/htdocs/licensing.html for details.
ps. berkleyDB is not a relational database in case you didnt know.

Good comparison tool can be found here: http://www.jpab.org/All/All/All.html
Notice also the Head to Head DBMS/JPA Comparisons

Most things have been said already, but I can just add that I've used HSQL, Derby and Berkely DB in a few of my pet projects and they all worked just fine. So I don't think it really matters much to be honest. One thing worth mentioning is that HSQL saves itself as a text file with SQL statements which is quite good. Makes it really easy for when you are developing to do tests and setup data quickly. Can also do quick edits if needed. Guess you could easily transfer all that to any database if you ever need to change as well :)

I am a big fan of DB4O for both .Net and Java.
Performance has become much better since the early releases. The licensing model isnt too bad, either. I particularly like the options available for querying your objects. Query by example is very powerful and easy to get used to.

What criteria will you use to evaluate these ? If you don't know yet, then you don't need to decide right now. Try to make your application as database-implementation-agnostic as you can - providing the appropriate wrappers, data access objects etc., and make this decision when you have all the facts to hand and you have to decide.
If you're using relational databases and SQL then the above shouldn't be too hard (using JDBC etc). Make sure you have plenty of surrounding tests so that when you want to switch between databases, you can determine that your application's functionality remains the same.
I ran into the same issue some time ago. I didn't know which database to go for, so my first solution used Derby (or HSQLDB?), and I was later able to switch to HSQLDB (or Derby ? Can't remember which solution worked) once I'd determined where I had issues (relating to performance) and which solution would really work for me.

I have used Derby and i really hate it's data type conversion functions, especially date/time functions. (Number Type)<--> Varchar conversion it's a pain.
So that if you plan use data type conversions in your DB statements consider the use of othe embedded DB, i learn it too late.
Latest Derby Version data type conversions

I personally favor HSQLDB, but mostly because it was the first I tried.
H2 is said to be faster and provides a nicer GUI frontend (which is generic and works with any JDBC driver, by the way).
At least HSQLDB, H2 and Derby provide server modes which is great for development, because you can access the DB with your application and some tool at the same time (which embedded mode usually doesn't allow).

I guess I'm a little late (a lot late;-)) to this post, but I'd like to add Perst, an open source, object-oriented embedded database for Java &.NET. for your consideration. Perst is an open source / dual license embedded database for Java. The distribution is compatible with Google's Android platform, and also includes Perst Lite for Java ME. We've even built an Android benchmark and produced a whitepaper on the subject...you can take a look here: http://www.mcobject.com/index.cfm?fuseaction=download&pageid=581&sectionid=133
All the best,
Chris

If I am correct H2 is from the same guys who wrote HSQLDB. Its a lot better if you trust the benchmarks on their site. Also, there is some notion that sun community jumped too quickly into Derby.

I realize you mentioned SQL browsing, but everything else in your question makes me want to suggest you also consider DB4O, which is a great, simple object DB.