Questions tagged [database-design]

For question about the design of the databases used by Stack Exchange. Consider adding the tag [database] or [architecture] as well. Do not use for database design questions in other contexts.

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How can a User's CreationDate be after they have posted?

I am currently analysing an Archive-Datadump of the When looking on the posts.xml together with the users.xml, there is a strange anomaly. The earliest CreationDate among ...
pzfn's user avatar
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4 votes
1 answer

Does Stack Exchange use event sourcing?

This is a more technical question. I just found that I can browse the history of all my actions. Does Stack Exchange use event sourcing and store all my actions in the database? I wonder if CQRS is ...
Konrad's user avatar
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3 votes
1 answer

How does a post end up in the review queue?

I've read about Review Tasks here and examined the tables here. My questions are: What kinds of posts get to the review table? (E.g., questions, answers,..) What is the qualifying factor? Who/what ...
John Miller's user avatar
8 votes
1 answer

Why does Stack Exchange use separate databases for each network site?

There are reasonable reasons for why separate sites are appropriate for Stack Exchange according to what it aims to be, and some of them are discussed here : Why is Stack Exchange split into multiple ...
4r4sh's user avatar
  • 123
3 votes
0 answers

Where are the user's notifications stored?

Looking at the Stackoverflow's DB architecture, I wonder where does each user's notification get stored? For instance, someone answers a post I created, I am notified about it thanks to the top-bar ...
Mik378's user avatar
  • 173
4 votes
1 answer

Does Stack Overflow use EventSourcing to keep tracking of each change on a post edit?

I'm curious to know how does Stack Overflow store the revisions/versions of each post edition in the database? Does it represent each edition version in the database, following the Temporal Pattern? ...
Mik378's user avatar
  • 173
19 votes
0 answers

Data Explorer execution plans are no longer available because SHOWPLAN permission is denied [closed]

I noticed after a recent maintenance downtime that now I get the following message when trying to include an execution plan with a query: SHOWPLAN permission denied in database 'StackOverflow'. ...
Paul Sweatte's user avatar
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5 votes
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How are votes calculated on Stack Overflow

As far as I understand SO keeps votes in a separate table and calculates the post votes based on that data. So DB query can look like this assuming votes can be 1/-1. SELECT SUM(value) FROM votes ...
Tamerlane's user avatar
  • 493
0 votes
1 answer

Can we ask for reviews of data models or ER diagrams on Stack Overflow?

Is it OK to ask questions concerning the data model of a specific system on Stack Overflow?
Tassisto's user avatar
  • 503
8 votes
1 answer

How does Stack Overflow find 'Linked' questions?

How does Stack Overflow find 'Linked' questions? Does it store a list of links somewhere in the DB? Or does it extract them from posts/comments dynamically?
Eugene's user avatar
  • 467
15 votes
1 answer

Stack Overflow database model

I'm currently involved in a project to design and implement an in-house question-and-answer community for our university. We've explored some open source frameworks such as OSQA, but we are also ...
Bobbus's user avatar
  • 159
2 votes
0 answers

How are network site user profiles linked?

This is a technical question aimed at the Stack Exchange developers I'm wondering about the database storage of each Stack Exchange site. Is each site stored in it's own database? Mainly however, ...
Peter Bridger's user avatar
0 votes
2 answers

How can SO figure out the last active user on a post?

Does SO store post activity in a table? I'm asking because I notice, on the main page, the owner of the last activity is listed instead of the owner of the question. The posts table, as far as I can ...
Mohamad's user avatar
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9 votes
1 answer

How does SO store revisions?

How does SO store its revisions in the database? Does it use diffs? If so, what algo does it use?
pedro_sland's user avatar
1 vote
1 answer

Does Stack Exchange use a single database for all its sites? Or does it have a different instance for each?

All in the question title.
Andrew G. Johnson's user avatar
12 votes
1 answer

The real SO database schema (not public dump)

Is there any way (or real chance) to see the real SO database schema (not public dump)? I'm curious on how SO manages to scale so well. Does it use multiple databases? Or any kind of sharding ...
Graviton's user avatar
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1 vote
2 answers

The Article "Understanding the StackOverflow Database Schema"-- Is it An Officially Sanctioned Article?

I found that there is an article entitled Understanding the StackOverflow Database Schema, I wonder how and where did the author get the source of information? Is it from public SO blog posts and ...
Graviton's user avatar
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2 votes
1 answer

Why did Stack Overflow put questions and answers in the same database table? [duplicate]

Possible Duplicate: Why does SO store questions and answers in the same table? I took a look at SO's HTML. I noticed that the ID number of a given question was very close to its answers' ID ...
Luke101's user avatar
  • 89
38 votes
3 answers

Stack Overflow database design join issues

There are many questions already on meta-stackoverflow regarding the database schema, but here is another, that I don't think is a duplicate, so please read on. I read a description of the schema ...
Steg's user avatar
  • 381