I'm building up an online (paid) service used for business administration purposes. The database is structured like so:
I have a contacts table filled with persons, contact info and the like. Then I have a few other tables holding information about payments, agreements and appointments. Also statistics like how much money was transferred this month, how many hours worth of appointments this month and the like.
I'm using MySQL (but could also go for MSSQL or some other service if necessary) and I had no formal training in any programming language whatsoever (yet).
I'm building a WPF application for acces to this database. Also planning on building an app so users can access their data and plan new appointments and register payments on the go.
I'm going to go for a login system to verify their right to login and use my service.
My question is about how to structure this. I'm not an SQL expert nor have I had any formal training in SQL or any other programming language. What I do know though is that my client-side app is almost out of the alpha stage.
So far I have come up with two ways to structure this.
1. Users get a seperate database.
My original idea was to give each user a seperate database, this makes it easier to provide people with statistics. Also it makes it easier to spread the workload through multiple, seperate servers. People would login to a master/main server, where their login information is stored, fetch their server info and programatically be 'redirected' to their own database. Spreading these databases also make it easier to provide individual back-ups to users.
The down-side of this is the sheer quantity of databases I'd have to manage. I'm planning on ending up with hundreds of thousands of users. Let's just say I want the system to be able to provide to an infinite amount of users.
2. Everything is stored in one database.
It's also possible to store everything in one database. This would make the database structure somewhat more complicated (while it also makes the whole a lot simpler). I'd have to add 'AND consumer_ID='" + MyID + "' to every query. (Which ofcourse is possible) and add a few tables to handle statistics per user.
It would be simpler to provide every user with the same database updates. Maintenance would be easier.
The down-side of this is that it makes it harder to spread the workload to seperate servers, I'd have to build something to make it possible that seperate servers mirror each other. Also I'd have to make sure that the workload is automatically divided between the servers, instead of simply going for: Fill server with X databases, then new server, fill, new etc.
I'm not in the luxury of hiring someone with any SQL training.
The most important thing for me now is that the system can be easily maintained while still being safe and reliable. I'm an amateur developer, going to college next year. I don't want to spend 50% of my time maintaining the database.
I think I got the major part of the details you might need, if you need anymore please ask for them.
I thank you in advance :)
Just go with solution 2. The downside of spreading the workload to many servers is fullfilled by "partitioning", look here for a starting point: http://dev.mysql.com/doc/refman/5.1/en/partitioning-overview.html
Partitioning would allow you for example to put all information of a table containing even IDs for consumers on the one, all other on the second server. Or whatever you want...
But i wouldn't start that complicated: do you need that now? It burdens you (either way) with such a big additional overhead! You can also look into the NoSQL database world for solutions that can be spread to as many servers as you want with low effort. You loose SQL and it's ACID features in the most cases; if you need those NoSQL is not an option.
In my database I have tables that will grow at different speeds:
fairly static ones that I dont expect to grow much at all,
medium-grade ones that will grow somewhat linearly with number of users and their activity
fast-growing ones that will grow rapidly as they hold logged data points
I have been fretting a little bit about maintaining this database as it is growing. It is a balancing scenario:
A single database is easier to work with but it may have higher maintenance costs in the future
Multiple databases can be easier to maintain once the application is deployed, but will require more R&D time
Can you recommend one or the other solution based on your past experience?
Thanks,
I think that how fast the data grows is irrelevant. I think that it makes more sense to have databases split up based on something mapped to a real-world reason.
For example, Typically, we have one database per app that we write. We have a database for a Nutrition and Ingredients database, another one for Job Listings, etc. We do this because it's easier for us to keep track of which database affects which apps. (To avoid confusion in other words.)
But we do have one Common database that holds information that's used in multiple applications. (Such as corporate info, locations, etc) so that we can avoid data de-duplication. (Why maintain a list of locations in each database).
I'm not saying this is how you should structure your data, but I listed this as an example of a good reason to have data split across multiple databases.
Other than having different maintenance plans for databases with varying growth, I can't see any reason to split based on database activity.
Splitting them behind a load balancer is the same either way.. Maintianing them once they're deployed should be done in a controlled, pre-tested manner regardless of how fast the tables grow...
Unless I'm missing something, I don't see a good reason for it, but I don't see a good reason not to do it, either. If it makes sense for you, and simplifues your business process without adding confusion or other problems, then it makes sense in your situation, and I see no harm in it at all.
is mysql capable of managing the data for a site which holds lots of data (say with hundreds of millions of users)? which database would be the most capable/beneficial?
Wikipedia is based on MySQL. I don't think it has 100M users, but it must be close by now.
No database will handle hundreds of millions of users unless you know how to set it up properly. No single server could handle that kind of traffic, so you need to know how to setup replication and load balancing. Once you reach a certain level, there is no out of the box solution, only tools you can use. MySQL being a very capable tool.
There are a couple of answers to this.
Yes, MySQL can store hundreds of millions of records; you need to know what you're doing, have a decent database schema, pretty robust hardware, but you're not pushing the limits.
When you talk about "hundreds of millions of users", you're talking about a site along the lines of Wikipedia/Facebook/Google/Amazon in scale. You need a custom, highly cached, distributed architecture to run a site at that scale - and the traditional database driven application architecture will almost certainly not be enough. You could still store your data in MySQL, but you'd need a whole bunch of additional components to make it all work - and without knowing more about the application, nobody could tell you what that might be. At that scale, none of the commonly used databases would suffice, so MySQL is no better or worse than any of the other options...
Your question is really irrelevant, because creating a product or service that hundreds of millions of customers actually want is a much bigger and more difficult challenge than choosing a database engine.
If you're starting a business from nothing, pick a technical platform you already know and go with it: productivity and quick implementation will be more important than being scalable to a level you may never reach anyway.
If you do eventually become successful enough to have to deal with hundreds of millions of customers, then you'll certainly be able to raise the cash to buy whatever expertise and hardware you need.
INFORMIX-SQL 7.32 (SE) Linux Pawnshop App.
I have some users who own several pawnshops within a 100-mile radius. Each pawnshop app runs with SE. The only functionality these owners need are: ability to remotely login to any store in order to view transactions, running totals and consolidate daily totals at end of business day. This can be accomplished with dialup modems, as the app doesnt have any need for displaying BLOB's. At end-of-day, each stores totals are unloaded to a flat file and transferred to the owner's system.
What would my owners gain by converting to distributed db's?.. ability to find out if a stores customer has conducted business in another store or if another store has a desired inventory item for sale? (not important, seldomly happens). Most customers will usually do business with the same store and if they dont have a desired item for sale, they will visit the closest competitors pawnshop. What gains would distributed db's offer to accomplish the same functionality as described in the first paragraph?.. Pawnshop owners absolutely refuse to connect their production systems via the internet! They dont trust its security, even using VPN, Cisco, etc, or its reliability! In this part of the world, ISP's have a bad track record for uptime. I know of several apps which have converted from web to dialup because of comm problems!
Distributed DBs, more precisely Informix XPS and IDS, don't have just one advantage. If you care just about getting data from different places, you can accomplish it with just a design strategy. If you add a "branch_id", or something like that, you're done.
Distributed DBs have a lot of advantages, from availability to scalability. You must review all these things first.
Sorry for this kind of answer, but is really difficult to give you an straight answer about this topic.
CouchDB is a peer based distributed database system. Any number of CouchDB hosts (servers and offline-clients) can have independent “replica copies” of the same database, where applications have full database interactivity (query, add, edit, delete). When back online or on a schedule, database changes are replicated bi-directionally.
CouchDB has built-in conflict detection and management and the replication process is incremental and fast, copying only documents and individual fields changed since the previous replication. Most applications require no special planning to take advantage of distributed updates and replication.
Unlike cumbersome attempts to bolt distributed features on top of the same legacy models and databases, it is the result of careful ground-up design, engineering and integration. The document, view, security and replication models, the special purpose query language, the efficient and robust disk layout are all carefully integrated for a reliable and efficient system.
If you are not going to have general 90%+ uptime connection between the databases, then there isn't any benefit to distributed databases.
One main benefit is to give large businesses a 'failover' when one machine goes down or is unavailable. If they have the database distributed over three or four machines, then the loss of one doesn't impact their ability to do business.
A second major benefit is when a database is simply too big for one server to cope with. 'Internet scale' databases (Amazon, Twitter, etc) have that level of traffic. Walmart would have that level of traffic. A couple of storefront operations wouldn't.
I think that this is a context where there is little to gain from distributed database operation.
If you were to go towards distributed operation, I'd probably look towards using a simple ER topology, with the 'head office' store being the primary (root) node and the other shops being leaf nodes. You would then have changes to the individual store databases replicated to the HQ node; you might or might not also propagate the data back to the other stores. Especially with just two stores, you might in fact simply replicate all the information to both stores; this gives you an automatic off-site backup of the database. (You'd probably configure all nodes as root nodes in this case - at least, until a chain grew to, say, five or six nodes.)
This would give you some resiliency for disaster recovery. It would also allow the HQ (in particular) to see what is going on at each store.
My impression is that you are probably not discussing 'transactions per second' on average; the rate of transactions at a single store is probably a few transactions per minute, with 'few' possibly being less than one TPM. Consequently, the network bandwidth is unlikely to be a bottleneck at any point, even with dial-up speeds (though that might be borderline).
Let's say I want to build a gaming website and I have many game sections. They ALL have a lot of data that needs to be stored. Is it better to make one database with a table representing each game or have a database represent each section of the game? I'm pretty much expecting a "depends" kind of answer.
Managing 5 different databases is going to be a headache. I would suggest using one database with 5 different tables. Aside from anything else, I wouldn't be surprised to find you've got some common info between the 5 - e.g. user identity.
Note that your idea of "a lot of data" may well not be the same as the database's... databases are generally written to cope with huge globs of data.
Depends.
Just kidding. If this is one project and the data are in any way related to each other I would always opt for one database absent a specific and convincing reason for doing otherwise. Why? Because I can't ever remember thinking to myself "Boy, I sure wish it were harder to see that information."
While there is not enough information in your question to give a good answer, I would say that unless you foresee needing data from two games at the same time for the same user (or query), there is no reason to combine databases.
You should probably have a single database for anything common, and then create independent databases for anything unique. Databases, like code, tend to end up evolving in different directions for different applications. Keeping them together may lead you to break things or to be more conservative in your changes.
In addition, some databases are optimized, managed, and backed-up at a database level rather than a table level. Since they may have different performance characteristics and usage profiles, a one-size-fit-all solution may not be scalable.
If you use an ORM framework, you get access to multiple databases (almost) for free while still avoiding code replication. So unless you have joint queries, I don't think it's worth it to pay the risk of shared databases.
Of course, if you pay someone to host your databases, it may be cheaper to use a single database, but that's really a business question, not software.
If you do choose to use a single database, do yourself a favour and make sure the code for each game only knows about specific tables. It would make it easier for you to maintain things later or separate into multiple databases.
One database.
Most of the stuff you are reasonably going to want to store is going to be text, or primitive data types such as integers. You might fancy throwing your binary content into blobs, but that's a crazy plan on a media-heavy website when the web server will serve files over HTTP for free.
I pulled lead programming duties on a web-site for a major games publisher. We managed to cover a vast portion of their current and previous content, in three European languages.
At no point did we ever consider having multiple databases to store all of this, despite the fact that each title was replete with video and image resources.
I cannot imagine why a multiple database configuration would suit your needs here, either in development or outside of it. The amount of synchronisation you'll have to pull and capacity for error is immense. Trying to pull data that pertains to all of them from all of them will be a nightmare.
Every site-wide update you migrate will be n times as hard and error prone, where n is the number of databases you eventually plump for.
Seriously, one database - and that's about as far from your anticipated depends answer as you're going to get.
If the different games don't share any data it would make sense to use separate databases. On the other hand it would make sense to use one database if the structure of the games' data is the same--you would have to make changes in every game database separately otherwise.
Update: In case of doubt you should always use one database because it's easier to manage in the most cases. Just if you're sure that the applications are completely separate and have completely different structures you should use more databases. The only real advantage is more clarity.
Generally speaking, "one database per application" tends to be a good rule of thumb.
If you're building one site that has many sections for talking about different games (or different types of games), then that's a single application, so one database is likely the way to go. I'm not positive, but I think this is probably the situation you're asking about.
If, on the other hand, your "one site" is a battle.net-type matching service for a collection of five distinct games, then the site itself is one application and each of the five games is a separate application, so you'd probably want six databases since you have a total of six largely-independent applications. Again, though, my impression is that this is not the situation you're asking about.
If you are going to be storing the same data for each game, it would make sense to use 1 database to store all the information. There would be no sense in replicating table structures across different databases, likewise there would be no sense in creating 5 tables for 5 games if they are all storing the same information.
I'm not sure this is correct, but I think you want to do one database with 5 tables because (along with other reasons) of the alternative's impact on connection pooling (if, for example, you're using ADO.Net). In the ADO.Net connection pool, connections are keyed by the connection string, so with five different databases you might end up with 20 connections to each database instead of 100 connections to one database, which would potentially affect the flexibility of the allocation of connections.
If anybody knows better or has additional info, please add it here, as I'm not sure if what I'm saying is accurate.
What's your idea of "a lot of data"? The only reason that you'd need to split this across multiple databases is if you are trying to save some money with shared hosting (i.e. getting cheap shared hosts and splitting it across servers), or if you feel each database will be in the 500GB+ range and do not have access to appropriate storage.
Note that both of these reasons have nothing to do with architecture, and entirely based on monetary concerns during scaling.
But since you haven't created the site yet, you're putting the cart before the horse. It is very unlikely that a brand new site would use anywhere near this level of storage, so just create 1 database.
Some companies have single databases in the 1,000+ TB range ... there is basically no upper bound on database size.
The number of databases you want to create depends not on the number of your games, but on the data stored in the databases, or, better say, how do you exchange these data between the databases.
If it is export and import, then do separate databases.
If it is normal relationships (with foreign keys and cross-queries), then leave it in one database.
If the databases are not related to each other, then they are separate databases, of course.
In one of my projects, I distinguished between the internal and external data (which were stored in separate databases).
The difference was quite simple:
External database stored only the facts you cannot change or undo. That was phone calls, SMS messages and incoming payments in our case.
Internal database stored the things that are usually stored: users, passwords etc.
The external database used only the natural PRIMARY KEY's, that were the phone numbers, bank transaction id's etc.
The databases were given with completely different rights and exchanging data between them was a matter of import and export, not relationships.
This made sure that nothing would happen with actual data: it is easy to relink a payment to a user, but it's very hard to restore a payment if it's lost.
I can pass on my experience with a similar situation.
We had 4 "Common" databases and about 30 "Specific" databases, separated for the same space concerns. The downside is that the space concerns were just projecting dBase shortcomings onto SQL Server. We ended up with all these databases on SQL Server Enterprise that were well under the maximum size allowed by the Desktop edition.
From a database perspective with respect to separation of concerns, the 4 Common databases could've been 2. The 30 Specific databases could've been 3 (or even 1 with enough manipulation / generalization). It was inefficient code (both stored procs and data access layer code) and table schema that dictated the multitude of databases; in the end it had nothing at all to do with space.
I would consolidate as much as possible early and keep your design & implementation flexible enough to extract components if necessary. In short, plan for several databases but implement as one.
Remember, especially on web sites. If you have multiple databases, you often lose the performance benefits of query caching and connection pooling. Stick to one.
Defenitively, one database
One place I worked had many databases, a common one for the stuff all clients used and client specifc ones for customizing by client. What ended up happening was that since the clients asked for the changes, they woudl end up inthe client database instead of common and thus there would be 27 ways of doing essentially the same thing becasue there was no refactoring from client-specific to "hey this is something other clients will need to do as well" so let's put it in common. So one database tends to lead to less reinventing the wheel.
Security Model
If each game will have a distinct set of permissions/roles specific to that game, split it out.
Query Performance /Complexity
I'd suggest keeping them in a single database if you need to frequently query across the data between the games.
Scalability
Another consideration is your scalability plans. If the games get extremely popular, you might want to buy separate database hardware for each game. Separating them into different databases from the start would make that easier.
Data Size
The size of the data should not be a factor in this decision.
Just to add a little. When you have millions and millions of players in one game and your game is realtime and you have tens of thousand simultaneous players online and you have to at least keep some essential data as up-to-date in DB as possible (say, player's virtual money). Then you will want to separate tables into independent DBs even though they are all "connected".
It really depends. And scaling will be painful whatever you may try to do to avoid it being painful. But if you really expect A LOT of players and updates and data I would advise on thinking twice, thrice and more before settling on a "one DB for several projects" solution.
Yes it will be difficult to manage several DBs probably. But you will have to do this anyway.
Really depends :)..
Ask yourself these questions:
Could there be a resuability (users table) that I may want to think about?
Is it worth seperating these entities or are they pretty much the same?
Do any of these entities share specific events / needs?
Is it worth my time and effort to build 5 different database systems (remember if you are writing the games that would mean different connection strings and also present more security, etc).
Or you could create one database OnlineGames and have a table that stores the game name and a category:
PacMan Arcade
Zelda Role playing
etc etc..
It really depends on what your intentions are...