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

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8
votes
2answers
2k 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, ...
1
vote
4answers
226 views

Database design for objects with multiple states

Context I'm designing a database which, simplified, should be able to handle users sending job requests to each other, and after that a job can be started, finished, and reviewed. The design should ...
4
votes
2answers
103 views

best way to attach database structure for an open source project

I have a small project which I want to publish on github. The problem is that my project contains a database. I don't know what is the best way to attach the database structure. I may get the create ...
0
votes
1answer
80 views

Quickly write log entries from http requests in a MySQL database with high performance

When a dataset is saved in the software I use, a http request is triggered (fire-and-forget). Information like the timestamp, the user and the changes made are listed in the GET parameters. Now I ...
5
votes
1answer
386 views

Is this database design good? What JPA Entities should I create for this design?

I am trying my hands on JPA. For this I am thinking of using the example of a student admission process as shown in the diagram below. Is this design good ? Any suggestions for improvement are ...
0
votes
1answer
76 views

Database vs. server-sided scripting language [duplicate]

To keep my question short and to the point, consider this: $relation = $mysql->query("SELECT relation($loggeduser, $requesteduser) AS a")->fetch_assoc()['a']; if ($relation != BLOCKED) { ...
1
vote
1answer
206 views

A very simple database system with JSON

If we need to store some data in a database, but without the need of advanced SQL features, can we use this scheme (written here in Javascript / node.js) : // the DB will be in RAM ! var myDb = {}; ...
1
vote
2answers
90 views

Retry method for generating unique code

In an app, a user can initiate the generation a six-digit alphanumeric code (actually done via Web API). The code needs to be checked against a remote database to ensure it is unique. Other than for ...
7
votes
1answer
761 views

Log to file or to database table?

I'm developing a web application which uses MS SQL for various data: including users, user accounts, user licenses, license prices, invoices. I need to log users' real-time usage of the system, and ...
7
votes
3answers
211 views

How to model and store an entity which has “one or more” values

I'll use C# to design the model to be persisted Let's suppose I have the following entity: public class Episode { public int Id { get; set; } public string Title { get; set; } public ...
1
vote
1answer
90 views

More than 20 Records Inserted in a Span of 1 Sec

Well, this is not specific to any programming languages. I came across this situation in Android, iOS, PHP and .NET. The problem is many times I come across a situation while building IoT apps, where ...
0
votes
2answers
233 views

Dealing with several custom getters

I have a data structure with data units containing different types of data. I've wrapped the data in "Field" objects so that each field is able to independently parse user input in a desired way. ...
2
votes
1answer
245 views

Matching algorithms in context of data quality problems

I work for an organization that has lots of databases containing person information. The data quality is poor. One case was a surname I found like this (this is the worst-case scenario): Mark ...
2
votes
3answers
149 views

Best approach for storing huge data

I'll be handling 300,000+ users. Each user (after logging in) will be able to create lets say "folders", in each folder, users will create "name=value,name2=value2,name3=value3" entry pairs. Each name ...
0
votes
1answer
1k views

Designing a scalable schema for college database [closed]

I am trying to build back end for college ERP system. The system will be based on LAMP. These is the scenario: Colleges have 5 branches There are 4-6 classes in each branch. There are 80 students ...
0
votes
1answer
52 views

online database with partial access for clients

I'm trying to come up with an online database that my clients would have partial access to. This is for an artwork storage company. We have about 40 clients and would like each to have access to their ...
3
votes
2answers
600 views

Creating a separate table for images or adding “image fields” to many tables?

I need to create a database in which several tables have images. For example, users have profile pictures and uploaded ones and products have many pictures, as well. Is it better to have one MySql ...
4
votes
2answers
130 views

Using audit trail as time machine?

I would like to do SELECT * TABLE t (using data from 1st of march 2012) I already have a nice audit trail of all tables in the database. It basically makes a copy of all rows that change, storing ...
0
votes
1answer
67 views

How can I iterate over two loops of mismatched sizes, keeping them in sync?

I have a database table in which each row is one movie (with fields like 'title', 'director' and 'writer'), and a related table where each row is one screenshot from a movie (with the fields ...
3
votes
0answers
113 views

Why there is a drop of interest in DBMSs? [closed]

I was playing around with google trends explorer when I tried to compare three major DBMSs: MySQL, Oracle and MS SQL Server. As you can see there is a drop in the interest in these database ...
2
votes
1answer
159 views

Multiple websites and applications using one user database

I've got several applications and websites that will be built around one main application. In a perfect situation users will be able to register once and be able to log into the different applications ...
2
votes
2answers
273 views

architecture of database heavy application

A program I'm currently designing is extremely database heavy, almost anything the user does will alter the database, or read from it. Now I have one interface which defines all these operations, and ...
4
votes
3answers
161 views

How to track temporal changes in a database?

Imagine a software for theater owners. You can accept reservations for the different cinema halls. Each hall has a different number of seats. Say the owner wants to know how many people visited the ...
7
votes
4answers
1k 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 ...
5
votes
2answers
268 views

Why Do B+ Trees Have a Minimum Occupancy of 50%?

As far as I can tell, the basic operations (add, delete, search) on a B+ Tree would function the same if minimum occupancy was 1, or 1/3, or any other function on node size. All the sources available ...
0
votes
1answer
321 views

calculating the average of a value over a month [closed]

I am working on a project right now that is having me calculate monthly interest on a bank account. The way the interest is supposed to be calculated is as follows: Use the daily average to calculate ...
2
votes
1answer
243 views

Entity Framework Lookup Tables

I am coming from working with ADO.net DataSets and feel fairly comfortable with how they work. Mainly, I usually have a DATA table with a large number of REF tables for lookups. In DataSets it was ...
1
vote
0answers
145 views

Syncing structured data and files in Android App with an ORM?

I am developing an Android App which I have developed for iOS before. The app requires that structured data and files are synced across android devices. In iOS, I was using Core Data and synced to ...
2
votes
2answers
69 views

Bulk update in client-server application

Sometimes when coding a client-server application, the client needs to make a bulk update. For example: "mark all pending orders as dispatched". To implement these I typically write specific ...
1
vote
0answers
17 views

compare different approachs for saving related records whose values may change

On a web application for accounting services, I have the good old Invoice. To keep this example as simple as possible, each Invoice has many rows, and each row has its item with its price. At the ...
2
votes
1answer
104 views

Managing Database version controlled migrations using a list/table

I'm not much of an expert in the area but I am aware that solutions already exist to managing database migrations in version control, e.g. sqitch and liquibase. However I'm currently planning a small ...
1
vote
0answers
71 views

Automatically verifying INSERTs when building a PHP(5.3.3) application

I am building a form in PHP. I would like to automatically verify that INSERT queries are successful, and populate data correctly, as opposed to running queries in Workbench or MySQL with every code ...
2
votes
1answer
81 views

Proper tree NoSQL structure with focus on full-text searching

I developing an app with tree(folder-file) structure, on which I should perform full-text searches with MongoDB. I did a research on the best tree structure practices and found this great article, but ...
2
votes
3answers
345 views

What are the advantages/disadvantages of creating a new set of tables for each user?

I'm working/playing on an app where individual users' data will be completely independent from each other. Of course, there will be common tables for other parts of the app (e.g. "users"), but for the ...
0
votes
1answer
158 views

Would it make sense to have a database table with only one record for tracking site summary stats?

I'm creating a web site that deals with monetary transactions. Users can deposit funds into a wallet and use them on the site. I'd like to keep track of some stats for the web site, like revenue and ...
3
votes
2answers
286 views

Designing a system to archive databases with referential integrity

I have a very large Oracle database, with many many tables and millions of rows. I need to delete some of the rows end-to-end. By end-to-end, I mean, if I want to delete a row from a table then I must ...
0
votes
0answers
131 views

When to use a message queue as a web service database?

Does it make sense to implement a message queue system such as RabbitMQ or Kafka for the purpose of storing data in a queue? For example, this could be done in order to handle things such as ...
2
votes
1answer
181 views

Entity Framework Code First Centralized database deployment

I originally posted this on stack overflow but was told that here is a better place to ask this kinda stuff. I couldn't find any other similar answered question but if there is one please give me a ...
2
votes
3answers
1k views

What is a Database Environment?

I am going through Relational Database Design by JLM. I have come across words like database, data model, DBMS etc. which I am able to understand. But, I get confused when the author tries to use ...
1
vote
1answer
57 views

Reduce Operations on Distributed Databases

I would like to ask you about optimizing reduce operations (e.g. count) on multiple databases. Let's say there is a user table that is stored in various countries and sharding is made based on the ...
2
votes
1answer
1k views

Separation of retrieving data and business objects between DAL and BLL Layers

I did some research before posting this question. Among other questions or post, one of those is provided below. I could not get a clear mind how to determine.. Business Objects within a Data Access ...
3
votes
1answer
145 views

Fixing bad data in a database - redo or incremental

I have pseudo-ownership of a fairly old db (original data from 30 years ago; current design is >15 years old). In my opinion, the schema is pretty broken, and one of the implications of this is that ...
2
votes
1answer
141 views

Normalization 3NF and BCNF

If I have the following relation R = (A, B, C, D) And the functional dependencies: A -> B, B -> A, CDB -> A, CDA -> B The candidate keys are CDA and CDB. The third normal form says that ...
13
votes
3answers
3k views

Database schema for a ToDo list

I am trying to make a very simple todo list application with PHP, MySQL, Jquery templating and JSON... However, my schema seems to complicate things in JSON. What's the best way to do it? A new ...
2
votes
5answers
128 views

Using DDL commands in programming language [duplicate]

Hello I am a student with no industry experience. My question may sound dumb, but, me and my friends were having discussions on use of DDL directly in programming language (any language may be Java, ...
6
votes
4answers
466 views

Heterogeneous Associations - Data Modeling When an Object that Must Relate to One of Many Classes

Suppose you have 3 classes: ClassA, ClassB and ClassC. Now suppose you have a class Message. You want a one-to-many relationship between each one of those three classes and the Message. The goal is ...
1
vote
3answers
855 views

Database design: 4 types of users but have different functionality , separate or one table?

I have 4 types of users: Admins , normal user , company , service provider admins and normal user share some attributes (id .first name ,last name ,phone ,mail) company and service provider share ...
1
vote
1answer
73 views

How to associate both a collection and one item of this collection to an entity

I'm working on a project in which I have an entity, we may call Users and another entity Address. I want to define the entity User in a way that an user would have a collection of addresses ...
1
vote
1answer
240 views

What is the point behind building an abstraction layer PDO Adapter class instead of using native PDO?

I have built a PDO adapter class because I thought, at the time anyway, it would be a good idea. After fighting with it, it makes no sense to me. Isn't the design of PDO the way it is to keep you ...
1
vote
1answer
185 views

Transferring information between a web server and a Python backend?

I have been Googling my problem but haven't been able to come up with anything; here's the situation: I have a PHP / MySQL website hosted with 1and1.com. I also have a Python program that runs on a ...