This is my large question: https://stackoverflow.com/questions/8803690/designing-a-website someone in the comments asked me to split that question up in more answerable questions, so here i go.
In short: I'm creating a webapp, people can join and write messages (and react).
I want to store the user information (usernames, passwords, who's friends with wo) in the MySQL-database, because MySQL is a relational database. The messages (and reactions on them), I want to store those in a document-orientend database (MongoDB).
A few months ago, I saw a presentation about a ecommerce site (i really don't know the name anymore, but in the USA it's really big I think), and they store product details in the mongoDB and user information, billings, ... in the MySQL. On the mongoDB site, it states that is well-suited for storing comments, profiles, session data, ... .
For searching, i want to use SOLR with the MySQL-database (not with the mongoDB because I want only to let users search for other users - those are stored in the MySQL-database - not for comments).
Yes, you can use two databases for two different purposes. Many cool sites do that.
Related
Here I come again ;)
I am doing an application where each user will have their own DB.
Is it ok if I store session for each user in their individual DB? Or is it for some reason convenient to have active sessions in a common DB for all users?
Sorry about my question, I am kind of new to this level. :) I am working with PHP and MySQL, if that makes any difference, although I thik the question is language independent.
In a typical application, there will only be one database with several tables, where each table can have several records.
Sessions
You can just save sessions the same way you would add a record to database.
Profile Details / Friendship
This is where relationships take place.
Consider the image below. Credits to the owner on w3stack(dot)org.
Focus and try to study on the three tables above: Users, Friendships, Friends(virtual table). Ignore the virtual table concept for now, so you will not be much confused.
It is really a BAD, and I mean BAD approach to create individual databases for each users. What if you thought of adding a "following" and "follower" feature to your application? You would need to add another table, and re-add all those friends from another db. If UserA will have 100 friends with each database, you wouldn't want to query all those 100 databases.
To end, just use a single DB, and identify relationships according to your application features. It is important to plan your structure before you actually apply it on hands-on. Happy coding!
I'm currently developping an application which allows doctors to dinamically generate invoices. The fact is, each doctors requires 6 differents database tables, and there could be like 50 doctors connected at the same time and working with the database (writing and reading) at the same time.
What I wanted to know is if the construction of my application fits. For each doctors, I create a personnal Sqlite3 database (all database are secure) which only him can connect to. I'll have like 200 Sqlite database, but is there any problems ? I thought it could be better than using a big MySQL database for everyone.
Is this solution viable ? Will I have problems to deal with ? I never did such an application with so many users, but I thought it could be the best solution
Firstly, to answer your question: no, you probably will not have any significant problems if a single sqlite database is used only by one person (user) at a time. If you highly value certain edge cases, like the ability to move some users/databases to another server, this might be a very good solution.
But it is not a terribly good design. The usual way is to have all data in the same database, and tables having a field which identifies which rows belong to which users. The application code is responsible for maintaining security (i.e. not to let users see data which doesn't belong to them), and indexes in the database (which you should use in all cases, even in your own design) are responsible for making it fast.
There are a large number of tutorials which could help you to make a better database design; a random google result is http://www.profsr.com/sql/sqless02.htm .
This question already has answers here:
Should I use a single or multiple database setup for a multi-client application? [closed]
(9 answers)
Closed 9 years ago.
I'm currently working on a site which will offer a blog for users to write.
My question relates to how to structure the database.
So all of you know how blogs are working. Some user posts an entry and the system puts it in the database. Now to the problem:
Is it better to have thousands of databases for each user and each blog? e.g. User A has a blog with its' entries and photos and got its own database "UserABlog" for it. User B, too, with the database "UserBBlog".
Or is it better to have a single database for all users which has a table for "entries" and "photos", etc. linked to each user via foreign keys? e.g. User A and B got their blogs and their entries and photos are saved in the database "blogs" in the tables "entries" and "photos" with foreign keys linked to User A, B and C.
Use one database.
TL;DR:
blogs do not generate much data
Blogs are simple
You can partition large tables
Compared to other applications which have to deal with real time data, workflows and similar stuff blogs produce only tiny amounts of data. Most databases are built to handle big amounts of data and will happily handle hundreds or thousands of blogs.
Blogs usually do not have to deal with complicated security settings and access rules so you can create a pretty good implementation even without dedicated databases.
If you database grows to big you can still partition the tables. http://www.mssqltips.com/sqlservertip/2888/how-to-partition-an-existing-sql-server-table/
I'd say go with the 1 database, it's all the same application. It's much harder to control and modify schema of tables if you have to manage 1 database per user.
Problem statement: I am working on a application in which a user can follow other users (like twitter or other e-commerce sites) and get their updates on his wall.It is in relation to a merchant and a user. A user can follow any merchant.The user himself can be a merchant,so actually its like a user following other users(Many-many realtion).
Issue: The easiest way to go about it was to have a junction table which will have
id (auto-increment) | follower_user_id | followed_user_id. But I am not sure when the database grows vertically,how well will it scale.If a user follows 100 people there would be 100 entries for a single user.In that case if I want to get the followers of any user it would take longer time for the query to execute.
Research: i tried studying twitter and other websites and DB designs,but they use different databases like graph based Nosql etc to solve their problems.In our case its Mysql.I also went about using caching mechanism but I would like to know,if there is any way I could store the values horizontally i.e each user has his followers in a single row(comma separated would be tedious as I tried it).
Can I have a separate databse for this feature something like Nosql based database (mongo etc). What impact would it have on performnce in different cases?
if my approach of going with the easiset way is right how can I improve the performance for say 5-10k users(looking at a small base now)?Would basic mysql queries work well?
Please help me with inputs over the same.
The system I use (my personal preference) is to add a 2 columns on the users, following and followers and store a simple encrypted json array in it with the ID's of followers and the users that are following..
Only drawback is that when querying you have to decrypt it then json_decode it but it has worked fine for me for almost 2 years.
After going through the comments and doing some research I came to the conclusion that it would be better I go the normal way of creating the followers table and do some indexing and use caching mechanism for it.
Indexing as suggested composite indexes would work well
For caching I am planning to use Memcache!
i am working on a project in which people can create a playlist and its stored in localStorage as objects. everything is client side for the moment.
so i will now like to take a leap forward, make a user login system (i can do it using php mysql and fb connect or oauth system, any other suggestions?). the problem is deciding if i make a sql database for each user and store their playlist (with media info) or is there any other way to go around. will handling a large number of databases be a trouble for me(in terms of speed)?
how about i create only one db as follows:
user database ---> one table containing{ user(primary key) pass someotherInfo} , then tables per USER {contains playlists) , 3rd table per playlist (containing userID and media info, what could be my primary key?)
example:
i have 10 registered user, each user has 2 playlists
1.table 1: 10 entries
2.table(s): username - playlists (10 tables) || i make one table with one field user other field playlist name
3.tables: each playlist - media info, owner (20 tables)
or is there a simpler way?
i hope my question is clear.
PS: i am new to php and database (so this might be very silly)
Surprised most answers seems to have missed the question, but I'll give this a try;
This is called data modeling (how you hobble a bunch of tables in a database together in order to express what you want in the best possible way), and don't feel silly for asking; there are people out there who spend all their waking hours tweaking and designing data models. They are hugely important to the well-being of any system, and they are, in truth, far more important that most people give them credit for.
It sounds like you're on the right path. It's always a good tip to define your entities, and create a table per each, so in this case you've got users and playlists and songs (for example). Define your tables thusly; USER, SONG, PLAYLIST.
The next thing is defining the names of fields and tables (and perhaps the simplistic names suggested above are, well, simplistic). Some introduce faux namespaces (ie. MYAPP_USER instead of just USER), especially if they know the data model will extend and expand in the same database in the future (or, some because they know this is inevitable), while others will just ram through whatever they need.
The big question will always be about normalization and various problems around that, balancing performance against applicability, and there's tons and tons of books written on this subject, so no way for me to give you any meaningful answer, but the gist of it for me is;
At what point will a data field in a table be worthy of its own table? An example is that you could well create your application with only one table, or two, or 6 depending on how you wish to split your data. This is where I think your question really comes in.
I'd say you're pretty much correct in your assumptions, the thing to keep in mind is consistent naming conventions (and there's tons of opinions of how to name identifiers). For your application (with the tables mentioned above), I'd do ;
USER { id, username, password, name, coffee_preference }
SONG { id, artist, album, title, genre }
PLAYLIST { id, userid }
PLAYLIST_ITEM { id, songid, playlistid, songorder }
Now you can use SQL you get all playlists for a user ;
SELECT * FROM PLAYLIST WHERE userid=$userid
Or get all songs in a playlist ;
SELECT * FROM SONG,PLAYLIST_ITEM WHERE playlist_item.playlistid=$playlist.id AND song.id=playlist_item.songid ORDER BY playlist_item.songorder
And so on. Again, tomes have been written about this subject. It's all about thinking clearly and semantically while jotting down a technical solution to it. And some people have only this as a career (like DBA's). There will be lots of opinions, especially on what I've written here. Good luck.
You can use either an SQL database like MYSQL or Postgresql or a NOSQL database like MongoDB. Each has it's pros and cons but since you seem like a beginner i am going to suggest MYSQL because it's what most beginners work with. Take a look at these articles
http://dev.mysql.com/tech-resources/articles/mysql_intro.html
http://www.redhat.com/magazine/007may05/features/mysql/
Of course you may feel free to do you own searching on The Big G as there are tons of resources out there.