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Questions tagged [database]

This tag is for general database questions; if you question is specific to SQL use that tag instead.

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31
votes
7answers
105k views

How to quickly search through a very large list of strings / records on a database

I have the following problem: I have a database containing more than 2 million records. Each record has a string field X and I want to display a list of records for which field X contains a certain ...
31
votes
4answers
20k views

How to prevent race conditions in a web application?

Consider an e-commerce site, where Alice and Bob are both editing the product listings. Alice is improving descriptions, while Bob is updating prices. They start editing the Acme Wonder Widget at the ...
31
votes
1answer
25k views

What is a realistic, real-world, maximum size for a SQLite database?

According to this article on Appropriate Uses For SQLite it says that, while SQLite is limited to 140 terabytes, a client/server RDBMS may work better: An SQLite database is limited in size to 140 ...
31
votes
4answers
13k views

How do you decide what kind of database to use?

I really dislike the name "NoSQL", because it isn't very descriptive. It tells me what the databases aren't where I'm more interested in what the databases are. I really think that this category ...
30
votes
8answers
16k views

Front end first or Back end first. Of the two which is a Good system design pratice?

I have a client right now requiring me to develop a school enrollment system. Now this is the first time im having this kind of challenge. Most of the past software that i created are not that complex....
30
votes
1answer
24k views

Dynamic form builder forms and database design? [closed]

Say your users can create their own web-based forms (textboxes, selects, etc) and publish them on the web for their users to fill out. Does anyone have a resource or any advice on how to architect ...
29
votes
1answer
22k views

When should you use a document vs relational vs graph database? [closed]

For the purposes of discussion let's consider a FourSquare scenario. Scenario Entities: Users Places Relationships: Checkins: users <-> places, many to many Friends: users <-> users, many ...
28
votes
2answers
14k views

Why store flags/enums in a database as strings instead of integers?

I've been browsing SQL dumps of some famous CMSes, including Drupal 7, Wordpress (some quite very old version), and some custom application based on Python. All of these dumps contained data with ...
27
votes
5answers
23k views

What is the difference between all-static-methods and applying a singleton pattern? [duplicate]

I am making a database to store information about the users of my website (I am using stuts2 and hence Java EE technology). For the database I'll be making a DBManager. Should I apply singleton ...
27
votes
3answers
18k views

How to efficiently store big time series data?

I need to store and to be able to query some very large amounts time series data. Properties of the data are as follows: number of series : around 12.000 (twelve thousand) number of data points, ...
26
votes
3answers
11k views

Is inline SQL still classed as bad practice now that we have Micro ORMs?

This is a bit of an open ended question but I wanted some opinions, as I grew up in a world where inline SQL scripts were the norm, then we were all made very aware of SQL injection based issues, and ...
26
votes
3answers
15k views

Is there a list of common usernames to reserve in a new system?

I need to reserve usernames in my new website. These generally fall into three categories 1) usernames no-one should have (eg: admin, user, service, help, root, etc) 2) names of super famous people ...
26
votes
3answers
38k views

Keep user and user profile in different tables?

I have seen in a couple of projects that developers prefer to keep essential user info in one table (email/login, password hash, screen name) and rest of the non essential user profile in another (...
25
votes
8answers
17k views

What's a universal way to store a geographical address/location in a database? [closed]

What's a correct format of a geographical address/location which is a good fit for any address on the Earth? At the moment I have: country city street number text data (for simplicity) zip lat/lng ...
25
votes
13answers
4k views

Why aren't databases integrated as a language feature?

Are there any programming languages that have a built-in database as a first-class language feature rather than connecting to an external SQL (or other) database? What would be the drawbacks and ...
25
votes
6answers
5k views

Databases and Unit/Integration Testing

I have had a discussion with someone about unit/integration testing with web applications and I have a disagreement about 1 core idea. The issues is that the person I am talking to think that the ...
25
votes
1answer
16k views

Redis vs Zookeeper

It seems silly to compare these two servers considering that they're meant for very different things. But if you think about it, they can do lots of similar things: store configuration data, ...
24
votes
2answers
16k views

What is the difference between collation and character set?

I have a general question about databases. We usually use the term collation with databases. I would like to know how its different from character set. I guess collation is a subset of character set. ...
24
votes
3answers
14k views

Conflict resolution for two-way sync

How do you manage two-way synchronization between a 'main' database server and many 'secondary' servers, in particular conflict resolution, assuming a connection is not always available? For example, ...
24
votes
4answers
64k views

Best way to synchronize data between two different databases

I have to implement data synchronization between two big databases which have completely different structures. Basically, I need to grap some data about products in different tables in the first ...
23
votes
7answers
6k views

Safely fixing production database data

Bugs happen and sometimes data has to be fixed in production. What is the safest way to go about this from a big company standpoint? Are there tools that can help? Here are some considerations driving ...
23
votes
12answers
11k views

What are the advantages of storing xml in a relational database?

I was poking around the AdventureWorks database today and I noticed that a number of tables (HumanResources.JobCandidate and Sales.Individual for example) have a column which is storing xml data. ...
22
votes
7answers
6k views

Advantages and disadvantages of using bit masks in database

Not so long ago I talked to my colleague and he was definitely against using bit masks because it is hard to understand all the values that are stored in the database. In my opinion it is not always a ...
22
votes
11answers
4k views

Creating a secondary primary key in a database for some tables

To some of my tables I want to add "second_primary_key" which will be uuid or some random long key. I need it because for some tables I don't want to expose integers to my web application. That is, on ...
22
votes
3answers
8k views

Store images in the database, or in files with a database link?

Is it appropriate to store the image files in the database? Or it would be better to store only the path of the file in the database, while keeping the file itself on the server? Are there any other ...
22
votes
6answers
20k views

At what size of data does it become beneficial to move from SQL to NoSQL?

As a relational database programmer (most of the time), I read articles about how relational databases don't scale, and NoSQL solutions such as MongoDB do. As most of the databases I have developed ...
21
votes
9answers
2k views

In agile development, should I try persistence in flat file before database?

Somebody explained to me that since in agile development, policy and the application logic should be more important than details such as persistence method, persistence decision should be taken at the ...
21
votes
3answers
10k views

How to store prices that have effective dates?

I have a list of products. Each of them is offered by N providers. Each providers quotes us a price for a specific date. That price is effective until that provider decides to set a new price. In ...
20
votes
9answers
2k views

Constraints in a relational databases - Why not remove them completely?

Is there any reason to build constraints between tables (inside SQLserver) nowadays? If so, when? Most applications in my area are built on object principles and tables are joined on demand. Demand ...
20
votes
4answers
3k views

What are the practices you follow to avoid wrong data updates in big databases?

A typical advice before any production deployments is backup the DB first. This way, if the new update has some issue that can lead to potential data loss or logical data corruption, then you still ...
20
votes
3answers
7k views

How to store ordered information in a Relational Database

I am trying to understand how to properly store ordered information in a relational database. An example: Say I have a Playlist, consisting of Songs. Inside my Relational Database, I have a table of ...
20
votes
4answers
6k views

Using flat files vs database/API as a transport between a frontend and backend

I've got an application which has generated a rather heated discussion between a couple of the developers. Basically, it's split into a web layer and a backend layer. The web layer collects ...
19
votes
4answers
3k views

How to create better OO code in a relational database driven application where the database is poorly designed

I am writing a Java web application that consists mainly of a bunch of similar pages in which every page has several tables and a filter that applies to those tables. The data on these tables comes ...
19
votes
3answers
30k views

Why to use web services instead of direct access to a relational database for an android app?

I searched on the web how to access in an efficient manner to a central database at a remote location and I met suggestions to use web services instead direct access (i.e. JDBC etc ) to a database.I ...
19
votes
8answers
5k views

Handling deleted users - separate or same table?

The scenario is that I've got an expanding set of users, and as time goes by, users will cancel their accounts which we currently mark as 'deleted' (with a flag) in the same table. If users with the ...
19
votes
7answers
29k views

Ways to have a history of changes of database entries

What are ways to allow the versioning of database entries (data)? Think of the content-managment-systems abilities to revert back changes of articles. What are their pros/cons?
19
votes
3answers
879 views

Relational databases and iterative development

In many approaches to software development like agile methodologies, Domain-Driven Design and Object Oriented Analysis and Design, we are encouraged to take one iterative approach to development. So ...
18
votes
10answers
3k views

My father is a doctor. He is insisting on writing a database to store non-critical patient information, with no programming background [closed]

So, my father is currently in the process of "hacking" together a database using FileMaker Pro, a GUI based databasing tool for his small (4 doctor) practice. The database will be used to help ease ...
18
votes
4answers
583 views

Database abstraction — is it being overdone?

After being exposed to numerous database abstraction layers, I'm starting to wonder what the point is of every library inventing their own different paradigm to access data. Picking up a new DAL feels ...
18
votes
5answers
16k views

When should a database table use timestamps?

First a note, I thought maybe this question belonged in the database exchange, but I think it is more broadly related to a programming solution as a whole than to databases. Will move to database ...
18
votes
8answers
16k views

How would you design a user database with custom fields

This question is around how should I design a database, it can be relational / nosql databases, depending on what will be the better solution Given a requirement where you'll need to create a system ...
18
votes
3answers
20k views

Why aren't Object Oriented databases used as much as Relational Databases? [closed]

I have come across many relational database management systems (RDBMS). But recently I used hibernate which made me start wondering why Object Oriented databases aren't more popular. If object ...
17
votes
8answers
8k views

When does one hard-code actual data values into the code as opposed to using a DB?

A long-standing question for me has been: when do I store data (actual values) in a database table, and when do I store them right in the code? The untold consensus has typically been as such(*): If ...
17
votes
4answers
3k views

Why not use SQL instead of GraphQL?

Recently I learned about GraphQL which claims to be superior to RESTful. However, I started wondering why don't we simply put SQL statements into an HTTP GET request. For example, in GraphQL I would ...
17
votes
4answers
3k views

Do I need IDs in my database if the records could be identified by the date?

I am writing my first application for Android and will use the SQLite database so will be trying to limit the size as much as possible, but I think the question applies in general to database design. ...
17
votes
5answers
2k views

Is having functionality in DB a road block to scalability?

I may not be able to give the right title to the question. But here it is, We are developing financial portal for wealth management. We are expecting over 10000 clients to use the application. The ...
17
votes
4answers
1k views

Database design - Store state or compute state every time?

Let's say I have a relational database application and a "user" object and a "message" object. Now I want to show the number of unread messages to this user. What's the best way to archive this? Do I ...
17
votes
7answers
816 views

De-facto standards for customer information record [closed]

I'm currently evaluating a potential new project that involves creating a DB for typical customer information (userid, pwd, first & last name, email, adress, telfnr ...). At this point, ...
17
votes
8answers
7k views

What qualifies “too many database requests” in code?

This is a discussion myself and some of my colleagues are having and thought I'd come out here and see what if there's a general consensus on it. It basically comes down to the following 2 opinions ...
17
votes
2answers
18k views

Best method to implement a filtered search

I would like to ask you, your opinion when it comes to implement a filtered search form. Let's imagine the following case: 1 Big table with lots of columns It might be important to say that this SQL ...