Large Database System

Hi there,

We have been looking for some time now for a database system that can
fit a large distributed computing project, but we haven't been able to
find one.
I was hoping that someone can point us in the right direction or give
us some advice.

Here is what we need. Mind you, these are ideal requirements so we do
not expect to find something that fits entirely into what we need
but we hope to get somewhat closer to that.

We need a database/file system:
1. built in C preferrably ANSI C, so that we can port it to Linux/
Unix, Windows, Mac and various other platforms; if it can work on
Linux only then it is OK for now
2. that has a public domain or GPL/LGPL licence and source code access
3. uses hashing or b-trees or a similar structure
4. has support for files in the range of 1-10 GB; if it can get to 1
GB only, that should still be OK
5. can work with an unlimited number of files on a local machine; we
don't need access over a network, just local file access
6. that is fairly simple (i.e. library-style, key/data records); it
doesn't have to have SQL support of any kind; as long as we can add,
update, possibly delete data, browse through the records and filter/
query them it should be OK; no other features are required, like
backup, restore, users & security, stored procedures...
7. reliable if possible
8 .local transactional support if possible; there is no need for
distributed transactions
9. fast data access if possible

We can not use any of the major commercial databases (e.g. Oracle, SQL
Server, DB2 or larger systems like Daytona...) obviously because of
licensing and source code issues. We looked closer to MySQL,
PostgreSQL but they are too big and have way too many features that we
do not need. We need to be able to install a database/file system on
possibly tens of thousands of machines and we also expect it to work
without administration.
On top of that, we might end up with thousands of files of different
sizes on each machine. Are there any embedded (i.e. "lighter")
versions of these two databases?
We haven't been able to find anything like that. I am not sure how
much work would involve in "trimming" down some of these databases,
but that doesn't seem to be too easy to do.
Berkeley-DB would have been the best but is now under Oracle hands and
the licence has changed. TinyCDB was a close call, but the fact
that we need to rebuild the database for each data update is making it
unfeasible for large files (i.e. ~1Gb). SQL Lite is very interesting,
but it has many features that we don't need, like SQL support.

Right now we are using plain XML files so anything else would be a
great improvement.

Any suggestions or links to sites or papers or books would be welcome.
Any help would be greatly appreciated.

If this is not in the proper forum I appreciate if someone can move
the post to the right location or point us to the right one.

Thanks in advance.

Best regards,
Ovidiu Anghelidi
ovidiu@intelligencerealm.com

Artificial Intelligence - Reverse Engineering The Brain

re: Large Database System

On Oct 19, 7:54 am, raidv...@yahoo.com wrote:Say that last sentence out loud in front of a group of DBAs and I
guess you will get a little bit of mirth. This statement alone is
proof that your project will fail. Every database system (even simple
keysets like the Sleepycat database) needs administration.

Listen, you are going to have tens of thousands of points of failure
in your system. Is that what you really want? If you have (for
instance) 20,000 machines getting a big pile of data shoved down their
throat, you pretty much have a guarantee that a few hundred are going
to be out of space and that once a month a disk drive is going to fail
somewhere.
Do you know what happens to performance when you put thousands of
active files on a machine? Pretend that you are a disk head and
imagine the jostling you are going to receive.
They are the size that they are for a reason. It's not fat that gets
trimmed off to scale things down, it's muscle.
You do know that SQLite is a single user database?
I'll say.
The right thing to do is go to SourceForge and execute a few
searches. The pedagogic answer to to refer to newsgroup
news:comp.sources.wanted, but it's a ghost town.

I suspect that you have no idea what you are doing. Do you have any
concept about what is going to happen when your problem scales to
10GB? Get a consultant who understands the problem space or you'll be
sorry. By the way, this is definitely not the right forum for your
post -- which does not exactly make it appear that you have anything
on the ball. (Really a newsgroup post in general is the wrong
approach here).

I guess that FastDB or GigaBase might be suitable (WARNING! One
writer at a time). I also guess that you are going to severely need
the capabilities that you do not think you need at some point.
http://www.garret.ru/~knizhnik/databases.html

Another possibility is QDBM:
http://sourceforge.net/projects/qdbm/
I guess that you will like this one but also that it is the wrong
choice.

I don't know anything about your project but I think you need to
rethink your big picture of how you are going to solve it.

re: Large Database System

Hi there,

Thank you for taking the time to answer to the post.
We are using the BOINC distributed architecture for now, which seems
to already be working on hundreds of thousands of machines. We want to
add database capabilities to the data files that are being processed.
Because of the sheer number of machines involved in computations we
need to avoid that. If it will not be possible we'll have to stick
with XML until we find something better.
That is not a concern. When you are going to have the same data
replicated on 1 to 10 machines, reliability is no longer becoming an
issue.
I haven't been able to provide more details about the project but most
of the data will be historic in nature. Once a calculation is
performed that data will be stored and in most cases will no longer be
active. It will still be needed though. So having thousands of files
on a machine is not so bad. This is a not a classic database
application and that is why it probably seems strange, that features
like reliability which should be on top, are listed as last and are
not a concern.
That is exactly what we need. Data will be sent over the Internet to
other machines which will also use a single user database.
I have looked over there but I should probably search again.
Thank you.
If things go bad at 10 GB we can just go with 1 GB or if 1 GB is not
good we can go with 100 MB. We can always increase the number of files
and distribute the data on more machines. The ideal solution is to
have the data in large compact files.
Finding out about these two databases is a step forward and it seems
that is was worthy to post it in here. Again, I appreciate your time.
We will look closer at these.
I have looked at it before. It appears to be quite new and there are
not many people using it, and we do not want to go a narrow road that
is less traveled.
Thanks again.
Ovidiu

re: Large Database System

raidvvan@yahoo.com wrote:We already have such a thing in hashlib, with the exception of the
ability to easily store and recall from external files. Such a
facility can be added, but requires that the file mechanism knows
all about the structure of the database. So far hashlib is
completely independent of such structure. Available under GPL,
written in purely standard C:

<http://cbfalconer.home.att.net/download/>

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home.att.net>



--
Posted via a free Usenet account from http://www.teranews.com

re: Large Database System

On Oct 20, 10:53 pm, raidv...@yahoo.com wrote:I do not understand why you don't want to store your thousands of
files on a single database server and then let the machines check out
problems from the database server. It seems a much less complicated
solution to me. The administration is now confined to a single
machine.

I imagine it like this:
The data is loaded into a single, whopping database on a very hefty
machine (Ultra320 SCSI disks, 20 GB ram, 4 cores or more). There is a
"problem" table that stores the data set information and also the
status of the problem (e.g. 'verified', 'solved', 'checked out',
'unsolved'). The users connect to the database and check out unsolved
problems until all are solved and then check out solved problems until
all of them are verified.
What if you get 4 different answers? What if the data is damaged on
three of them? Reliability is always an issue. The more complicated
the system, the more difficult it will become to verify validity of
your answers.
Data reliability is always a concern. If you cannot verify the
reliability of the data, then nobody should trust your answers.
How will you coordinate who is working on what steps of the problem?
Since single user data access is what you are after, FastDB might be
interesting. If you compile it for 64 bit UNIX you can have files of
arbitrary size, and they are memory mapped so access should be very
fast. I have done experiments with FastDB and its performance is
quite good. You can use it as a simple file source but it also has
advanced capabilities. The footprint is very small.

I think we shold move the discussions to news:comp.programming, and so
I have set the follow-ups.