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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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17
votes
4answers
16k views

Handling database schema changes when pushing new versions

During times of heavy development, the database schema changes both rapidly and continuously, and by the time our weekly push to the beta build comes around, the schema has changed so much that the ...
16
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5answers
2k views

Is it the job of programmers to design the database?

I've been a programmer for the past six years. Throughout my career, I have worked on many web applications. Most of the time, when a database was needed, it was given to us (the programmers) or we ...
16
votes
7answers
27k views

Best practices to follow with database indexes [closed]

What are some DOs and DONTs for improving database performance using index? A DO would be a case in which an index should be created, or another indexes related tip that will improve performance. A ...
16
votes
9answers
11k views

How much database access should developers have? [closed]

So I've worked in many different workplaces as a developer and my level of access to the database has been varied. I typically don't have production db access. Most of the time I have access to the ...
16
votes
7answers
29k views

Are mutliple database calls really significant with a network call for a web API?

At one of my employers, we worked on a REST (but it also applies to SOAP) API. The client, which is the application UI, would make calls over the web (LAN in typical production deployments) to the API....
16
votes
7answers
70k views

What is faster? Using REST API or querying a database directly?

What is faster performance wise? Creating a REST API and having your web app use the REST API to do all interactions with your database OR querying your database directly (i.e. using whatever typical ...
16
votes
2answers
40k views

Are these SQL concepts for beginners, intermediate, or advanced developers? [closed]

I've been learning SQL recently and practicing with MySQL/Postgres and soon Oracle DB. I've also search the web for a 'road map' study of databases but couldn't find one, unfortunately. I want to ...
16
votes
6answers
19k views

HTTP Session or Database approach

I am confused a little as what should be my approach, Working on a design of shopping cart and i need to store shopping cart either in session or in database but not sure which approach would be best....
16
votes
4answers
3k views

How do I know my data is relational or object oriented in nature?

Just read these lines- If your data is object in nature, then use object stores ("NoSQL"). They'll be much faster than a relational database. If your data is relational in nature, the overhead ...
16
votes
4answers
4k views

Databases: Where should the application logic run? [duplicate]

http://highscalability.com/blog/2010/11/9/facebook-uses-non-stored-procedures-to-update-social-graphs.html talks about how Facebook moved logic out of the database into the application in order to ...
16
votes
4answers
2k views

Staying OO and Testable while working with a database

What are some OOP strategies for working with a database but keeping things unit testable? Say I have a User class and my production environment works against MySQL. I see a couple possible approaches,...
16
votes
3answers
19k views

How to handle monetary values in PHP and MySql?

I've inherited a huge pile of legacy code written in PHP on top of a MySQL database. The thing I noticed is that the application uses doubles for storage and manipulation of data. Now I came across ...
16
votes
3answers
7k views

What is the proper way to synchronize data across microservices?

I am relatively new to microservice architecture. We have a moderately sized web application and I am weighing the pros and cons of breaking it out into microservices instead of a monolithic system we ...
16
votes
4answers
7k views

Data architecture for event log metrics?

My service has a large ongoing number of user events, and we would like to do things like "count occurrence of event type T since date D." We are trying to make two basic decisions: What to store? ...
15
votes
4answers
2k views

Why do relational databases only accept SQL queries?

As far as I know, most relational databases do not offer any driver-level API for queries, except a query function which takes an SQL string as an argument. I'm thinking how easier it would be if one ...
15
votes
3answers
12k 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 ...
15
votes
7answers
4k views

Why shouldn't you develop on production database? [duplicate]

I need help with organizing my arguments for why it's MADNESS to develop against production data. Backstory: I started working here six months ago and I noticed we're developing directly against ...
15
votes
6answers
9k views

Isn't SQLite a bit underestimated? [closed]

Before I ask the question, let me first describe my thoughts about SQLite. I happen to like tools that are small, fast and, more importantly, have only the really necessary functionality. That's why ...
15
votes
7answers
12k views

Disadvantages of using a nullable foreign key instead of creating an intersection table

Say I have the following ER diagram: Now if I represented the relationship using a foreign key of School in Student, I could have NULL values (because a Student is not required to belong to a School),...
15
votes
2answers
6k views

Will B-Trees and Other Data Structures Become Obsolete With The Advent of Solid State Drives?

Many (perhaps most?) database applications today use B-Trees and variations to store data, because this data structure optimizes the read, write and seek operations on a hard disk (and these ...
15
votes
2answers
23k views

Why would I use ElasticSearch if I already use a graph database?

I don't find any deep explanation on the web about a comparison between ElasticSearch and the graph databases. Both are optimized to traverse data. ElasticSearch seems to be optimized for analytics. ...
15
votes
0answers
745 views

Is there a reason for not using JavaScript for direct database connections on a web site? [duplicate]

I am thinking about using JavaScript for direct connection to our database server. I think I have solutions to all the possible problems about it. Security: Modern database management systems support ...
14
votes
6answers
3k views

Do You Still Need Indexing After Database Normalization

After you have done a good normalization, do you still need to index the table? How is this going to affect the performance? Will it even affect the performance in some way after a good normalization? ...
14
votes
6answers
3k views

What are the best practices around retiring obsolete database columns? [closed]

I'm designing an application which will in an early stage collect data A, B, and C from clients, but later on will instead collect data A, B, and D. A, B, C, and D are very related and right now ...
14
votes
6answers
60k views

what do database programmers do?

Every time I read about Oracle programmers etc, I get confused. I don't know what exactly they do. From my understanding, application programmers need to develop the core functionality. The libraries ...
14
votes
5answers
8k views

Message Queue. Database vs Dedicated MQ

I am after advice regarding message queueing. We have requirements for "jobs" to be posted to a message queue. The original suggestion was just to use a SQL Server instance and process messages from ...
14
votes
5answers
9k views

When should we use MongoDB?

MongoDB is a NoSQL database which I've found quite easy to use. Recently I had to develop a simple application which needed to collect some data using HTTP requests and store some results after ...
14
votes
4answers
12k views

Will the Database connection be closed if we yield the datareader row and not read all the records?

While understanding how yield keyword works, I came across link1 and link2 on StackOverflow which advocates the use of yield return while iterating over the DataReader and it suits my need as well. ...
14
votes
3answers
4k views

General thought process for “How would you build this website/app” interview questions [closed]

I've collected a bunch of interview questions like "Describe how you would design a photo album application", "Describe how you would design this particular feature of this particular website" (e.g. ...
14
votes
5answers
7k views

Is there any reason to use VARCHAR sizes rounded to a 128/256/4096 byte offset?

In database schema's, I often notice VARCHAR sizes are rounded to the byte offsets 128/256 or 4096. I've done it before as well, and the idea behind it was probably something with efficiency. However,...
14
votes
4answers
7k views

How to handle Real Time Data from a database perspective?

I have an idea in mind, but it still confuses me the database area. Imagine that I want to show real time data, and using one of the latest browser technologies (web sockets - even using older ...
14
votes
3answers
1k views

Does ORM promote database de-normalisation?

Doctrine and Propel both make use of single and concrete table inheritance to map object relationships. The former sees all possible fields in the class tree mapped to a single table - whereas the ...
14
votes
3answers
3k views

How to handle foreign key constraints when migrating from monolith to microservices?

My team is migrating from a monolithic ASP.NET application to .NET Core and Kubernetes. The code changes seem to be going as well as can be expected but where my team is encountering a lot of discord ...
14
votes
2answers
9k views

Why NoSQL over SQL? [duplicate]

Possible Duplicate: When would someone use MongoDB (or similar) over traditional RDMS? How well the SQL and NoSQL go head-to-head. I read somewhere that SQL databases are not well for data that ...
14
votes
2answers
4k views

Should I keep email addresses as plaintext in database?

It's clear to everyone (I hope) that storing passwords without at least salting/hashing them is a terrible idea. What about emails? Let's say you keep the subscription email address, if you encrypt ...
14
votes
4answers
4k views

TDD with SQL and data manipulation functions

While I'm a professional programmer, I've never been formally trained in software engineering. As I'm frequently visiting here and SO, I've noticed a trend for writing unit tests whenever possible and,...
13
votes
6answers
2k views

In plain English, what is a database index most similar to? [duplicate]

Setup: Suppose you are teaching an introduction to Databases class, the students are CS students that have a working knowledge of tree structures, how they can speed up searches, and have probably ...
13
votes
4answers
7k views

Are database schema migrations a problem in production environments?

In discussions about NoSQL vs SQL databases, I sometimes hear that companies prefer to use schemaless NoSQL databases because it is problematic to migrate the schema to a new version. But is that ...
13
votes
5answers
2k views

For an ORM supporting data validation, should constraints be enforced in the database as well?

I have always applied constraints at the database level in addition to my (ActiveRecord) models. But I've been wondering if this is really required? A little background I recently had to unit test a ...
13
votes
5answers
14k views

When should use of database be preferred over parsing data from a text file?

I was making a Python program to measure the growth of codereview.SE. My approach was to get the "Site stats" shown on the front page and store them on my hard drive. I plan to do this once every day. ...
13
votes
4answers
20k views

Database History Table / Tracking Table

Currently I want to structure a tracking/history table like this: PrimaryKey - ID OtherTableId - fk fieldName - name of the field its tracking OldValue NewValue UserName CreateDateTime So basically ...
13
votes
7answers
2k views

Whats the best way to determine when it is appropriate to use a database?

I began my programming career in web development using PHP and MySQL. I got quite accustomed to utilizing db for storage of most dynamic data as well as some setting/parameter data. Sometimes there ...
13
votes
4answers
5k views

Benchmarking databases

I see lots of discussions flying around about performance of db 'x' or that moving from 'x' to 'y' improved our site performance. I'm yet to see proper benchmarking that works across different types ...
13
votes
2answers
15k views

single table w/ extra columns vs multiple tables which duplicate schema

I am working on a project where at some point, I needed to make a decision on whether or not, in the database, I should have a single table with multiple columns that not every record uses, or ...
13
votes
1answer
412 views

Can domain models in the database be a sustainable solution?

I just started at a new job as a database developer for a medium-small sized, company based on Microsoft-technology. I noticed early on how much practices deviate from what I've been taught at school ...
12
votes
5answers
2k views

How come the computer doesn't have to read the entire table when the column is indexed? [duplicate]

Let's say a table with two columns has 100 quadrillion records. And I want to find a record that has column #2 equal something. If column #2 is indexed it returns the result immediately, but if it's ...
12
votes
12answers
60k views

Using XML as data storage [closed]

I was thinking about the XML format and the following quote: “XML is not a database. It was never meant to be a database. It is never going to be a database. Relational databases are proven ...
12
votes
4answers
901 views

Does it ever make sense NOT to condense one to one relationships?

If we have Table A that has a one to one relationship with Table B, does it ever make sense to keep them apart? Or does it never hurt to combine them into a single table? Do either of these scenarios (...
12
votes
5answers
1k views

How to avoid violating the SRP in a class to manage caching?

Note: The code sample is written in c#, but that shouldn't matter. I've put c# as a tag because I can't find a more appropiate one. This is about the code structure. I'm reading Clean Code and trying ...
12
votes
5answers
3k views

Indexing a database

I am not so familiar with databases and now I am trying to understand the indexing mechanism. From what I know, in a RDBMS, indexing on a column makes searching by that column faster. This is also ...