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Free Small Stand-Alone DataBase?

Extrarius · 2006-04-12T22:58:00

For a project I'm working on, I'll need a free, small, stand-alone database that can be used for commercial applications. It's not that I'm selling a program, but the program will possibly be making money so I need something I can use for that without having to pay fees or open-source the project's code. I won't be distributing executables at all, so I *think* the GPL would be OK since (my understanding) is that it only requires that those that are given binaries are also given source. It won't need to support a large number of records, complex relations of any kind, high-volume traffic, or anything like that, but it does need to be reliable and it really needs to support searching by string indexes. Essentially, it will be used to store pairs consisting of a "UserName" (a string) and "Credit"(fixed-point number, though storing it as double precision should be fine). Queries won't be done often at all, maybe once a minute, but it support a decent number of queries just in case. Also, it should support some kind of "lock" operation to ensure that while one application instance is updating a record, no other application instances obtain the original or intermediate values. In general, a lock will last for up to 10 minutes, so it really needs to be a per-record thing. I'd also like to store what amounts to a log of credit going up and down based on various actions, so anything that would help with that would be great too. It's kind of like a virtual store, so this part would be multi-table, with one table storing a userID, transation ID, a timestamp, total amount of credit gained or lost, etc, and another table assocating transaction ID with item # and quantity sold/bought at what price. This will be insert-only, though, so it should be rather simple and should make use of very few (if any) locks, though it can probably be quite slow since the rate of insertion should be at maximum a few items a minute on average. So far, the only stand-alone database I've found at all is SQLite, which fails to meet my needs in many ways, but if it's all there is, I might have to end up hacking what I need out of it. Since I don't really need the full power of SQL, I'm thinking of rolling my own, but put simply I hate to do that because even the basic things I want can be difficult to get right, and I don't want to risk really screwing things up. If there are any good, inexpensive solutions, I might be willing to go with one of those, but I'll hold off at least until the application has passed basic testing before purchasing anything. If you know of any such databases that are small and stand-alone and either free or inexpensive, I'd appreciate pointers to them, comments on how they worked for you and how you used them, and any other feedback you can provide.

General and Gameplay Programming Programming

Started by Extrarius April 12, 2006 06:27 AM

21 comments, last by Extrarius 18 years ago

Extrarius

1,412

Author

April 12, 2006 10:29 AM

Unfortunately, the trade is not under my direct control, which is why I want long-term locks (start when the trade starts, end when it's confirmed by the game).

"Walk not the trodden path, for it has borne it's burden." -John, Flying Monk

Anonymous

April 12, 2006 09:57 PM

If this is for a single application (with multiple threads) then a hand crafted solution would be fastest and take up the least memory. Hash driven index resolution isnt that hard (including for strings...)

It might be possible that the entire DB can be memory resident (using simple transaction logfiles to protect against failures between DB sync image saves).
Otherwise random access files with memory resident hash indexing if your entire
dataset id too large...

InterThread record locks are likewise not that difficult to code (Critical Section protected Lock lists...)

A decent programmer could write the code in a day.

Extrarius

1,412

Author

April 12, 2006 10:58 PM

Unfortunately, it's for a single application that will have multiple instances running at once that need to access the same database. Of course, it's theoretically possible to make it a single application, but not at all simple and that would bring additional complications (such as eliminating the protection from other processes that the OS provides, and making it much more difficult to kill an individual instance should it hang, etc).

Also, it would be very difficult to make a utility to search the logs as well as is possible with even the simplest of the databases proposed in this thead.

"Walk not the trodden path, for it has borne it's burden." -John, Flying Monk

Free Small Stand-Alone DataBase?

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