Database design is the process of specifying the logical and/or physical parts of a database. The goal of database design is to make a representation of some "universe of discourse" - the types of facts, business rules and other requirements that the database is intended to model.

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Can I losslessly decompose this table?

I've stumbled across a database design problem that's out of my league, and my go-to DBA guru is off on fire drills. In essence, I have a table with the following primary key: child_id integer ...
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1answer
113 views

Adding nullable column to table costs more than 10 minutes

I have problems to add a new column on a table. I tried to run it a couple of times, but after more than 10 minutes running, I decided to cancel the query because of lock time. ALTER TABLE mytable ...
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3answers
1k views

Appropriate multi-language schema, or overkill?

UPDATE 2: I've actually ended up using this, and it's great after a couple tweaks. Here's my post on its actual design, and in action: http://tim.hithlonde.com/2013/lemon-schema-works/ I am building ...
7
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1answer
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Database design for handling 1 billion rows and counting

We receive real-time GPS data at a rate of around 5000 pr. minute (from 4 TCP servers). Each server uses a single connection to insert the data, and buffers data in between inserts. Every 15 minutes ...
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3answers
190 views

Choice- or ids-list- field representation

I wonder what is the best way to represent a user setting that could either take a value from a set (such as 'High', 'Medium' or 'Low') or be a list of IDs from another (or the same!) table (Many to ...
7
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230 views

How can I make my database more concise?

I am writing an application for Android using SQLite (backed by ORMlite if it matters). So far I'm in the conceptual stage and working on the database design. The database is being designed to contain ...
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6k views

SQL Server: query performance (search 2 million rows)

Got an interesting one for all of you SQL guru's out there. Now this search is only taking a couple of seconds, but it's quite intensive and there must be a better way. Maybe I'm expecting too much? ...
7
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1answer
1k views

Schema designing for handling multiple payment gateways

This is more of a question that requires feedback. I'm designing a database that handles multiple payment gateways. A payment gateway mostly requires a table for order details before making the ...
7
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1answer
323 views

Could Stack Overflow run on SQL Server Web Edition?

I am starting a new web venture that may need to scale to a high number of users. I am confident with the SPLA licencing for SQL Server Web edition, but want to know if I will need to factor in ...
7
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2answers
538 views

Best relational database structure for this data

I'm in the process of creating a database scheme for the following scenario: There are users Users have roles (such as "Developer" or "CEO") Roles have applications (such as "Topdesk") Applications ...
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6answers
2k views

Best way to document database mappings for migrations [closed]

I'm working on a project that includes mapping database elements for a migration and I wanted to know what tools others were using to do this? Excel is a very flexible way to document simple ...
7
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1answer
402 views

Temporal Validity and Primary/Foreign Key Relationships

I've read through several of the oracle tutorials that show temporal validity and time features. However, in the examples I'v read, there is no primary key used in the demo tables. ...
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1answer
278 views

Performance of query with a range condition and order by

We have the following table (in SQLite on Android) which a tree structure (Nested Set model) of words and their frequencies: lexikon ------- _id integer PRIMARY KEY word text frequency integer ...
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1answer
415 views

Designing Simple Schema for Disaggregation of Demand Forecast

I am doing a simple database design task as a training exercise where I have to come up with a basic schema design for the following case: I have a parent-child hierarchy of products (example, Raw ...
6
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5answers
6k views

Importance of ER Diagrams

I am a student and I am developing several projects as a part of my academia. While developing the database for one of the projects, we came across a situation where we thought about whether ERD is ...
6
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4answers
7k views

Is there a tool to check if my database is normalized to the third normal form?

I learned about normalization recently, and understand how important it is when implementing a new schema. How can I check if my database is 2NF or 3NF compliant ? Manual review is a sure option, ...
6
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4answers
503 views

Purpose of IDs in a User Table Database

In a table, such as a user table, where there will only be 1 row with a for any particular user, why have an ID field, let alone as the primary key?
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2answers
378 views

What is the name of this schema pattern

Its been a few years... but I've run into a problem-set that reminds me of a schema design pattern and I'm trying to recall the details. Essentially, the pattern consists of one database which is 3 ...
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4answers
617 views

How can a database be normalized when an optional field causes denormalization?

Suppose you have a warehouse full of widgets. Each widget in the warehouse is stored in a specific identifiable location within the warehouse. You might have a schema which looks like this: A ...
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How costly is opening and closing of a DB connection?

How CPU intensive is opening and closing of a DB connection (for a web app) in MySQL ... when the DB software is on localhost? ... when the DB software is on another machine?
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5answers
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Sharing a single primary key sequence across a database?

Is it an acceptable practice to use a single sequence as a primary key across all tables (instead of a primary key being unique for a given table, it is unique for all tables)? If so, is it ...
6
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2answers
2k views

Is one-to-one relationship normalized?

Consider we have a large set of statistical data for a record; e.g. 20-30 INT columns. Is it better to keep the entire set in one table as they all belong to a record OR creating a another table ...
6
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3answers
3k views

SQL Server Primary key / clustered index design decision

Looking for some advice regarding a table / index design decision I've got to make on some tables that I've got to port into SQL server from an existing 4GL based database. I've got a product history ...
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896 views

Increase all primary key values by 1

How do I increase all of my EmployeeID values by one if it is the primary key?
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PK as ROWGUIDCOL or use a separate rowguid column?

There's a long-winded debate going on here so I'd like to hear other opinions. I have many tables with uniqueidentifier clustered PK. Whether this is a good idea is out of scope here (and it's not ...
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4answers
646 views

Can this business logic be enforced by a conditional database constraint?

I am trying to duplicate the business logic embodied an intranet C# web application in the database so that other databases can access it and work under the same rules. This "rule" seems difficult to ...
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Visio 2010 and SQL 2012 - Reverse Enginnering

We have upgraded to SQL 2012 and Am trying to reverse engineer our Dbs into Visio 2010. I setup a connecting using SQL 11 driver and Visio complains that that driver is not supported. Any one run ...
6
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217 views

Dynamic contacts database

I'm trying to create a database for contacts. I must have many categories for every contact, like Home, Office, Emails, Phones. In every category one can add more than one value. Also the categories ...
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2answers
2k views

Why use separate databases for high traffic/volume tables?

While looking at the database structure of an application I am using I recognized that it uses 3 different databases on the same SQL Server instance for different things. The first one contains the ...
6
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6answers
742 views

What is the best database design for this situation?

I'm working on building a business application for my company and struggling to pick the most appropriate database design for a particular situation. Let's say I have the following entities: ...
6
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2answers
20k views

Add a new Column and define its position in a table

I have Table A with 5 columns: TableA -- Name Tel Email Address I want to add a new column (mobile) in between Tel & Email: TableA -- Name Tel Mobile Email Address If I use ALTER TABLE ...
6
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2answers
296 views

Should I add a column or 1-1 table if property is usualy null

There's a new unique property we need to add, which is relevant only to a specific subset (less than 1%). We thought it's better to add a new table which will be 1-1, than to add a new column which ...
6
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1answer
835 views

Are there any performance benefits to using a hash table with no clustered index?

I have this table: CREATE TABLE [dbo].[relatea] ( [mid] [varchar](16) NOT NULL, [sid] [varchar](16) NOT NULL ) It stores hash matches. Is there any benefit to having this as a heap? It has ...
6
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252 views

Design: How do you decide when items are related vs when they are attributes?

I've been trying to figure this out for a while. Let's say you have a person, for example. An attribute of a person is his or her social security number, right? But a person also has a social ...
6
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1answer
655 views

What makes an OLTP database an OLTP database?

This is a pretty broad question. I know the definition of OLTP. But it seems like unless you have an environment that has a clear distinction between OLTP and OLAP, in the sense of a database that ...
6
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1answer
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2NF decomposition + database normalization

If anyone knows about 2NF I'd greatly appreciate if you could tell me if my understanding of it correct my book does not even mention it (except to say is of "historical significance") and I haven't ...
6
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2answers
457 views

Using 100's of schemas in a database SQL2008R2?

We are in SSAS type of environment with 100's of clients. Currently each client gets a database and we have 200 per instance on SQL Server 2008R2. This presents limitations with snapmanager being ...
6
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3answers
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How to normalize Time Sheet data?

I am having a terrible time finding an appropriate way to store this data in a database. The current excel (simple) version looks something like this: http://i.stack.imgur.com/BEZOw.png Staff and ...
6
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1answer
520 views

Better to use a RANGE RIGHT or RANGE LEFT Partition Scheme

I'd like to know if it is better to use a RANGE RIGHT partition scheme or a RANGE LEFT partition scheme? Is one of these options by default a better choice, or is it heavily dependent on the actual ...
6
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3answers
212 views

Tracking changes on a table

I have a users table. I want to keep track of all the changes I have done,name,phone etc. I've thought to create an extra table changes that will store the id of the previous and the next version of ...
6
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2answers
716 views

Extracting entity from attribute in entity-relationship diagram

I am developing a database model where I need to capture information about rent contracts for parking places within a parking. I have thus defined an entity called PARKING CONTRACT. Requirements (r.) ...
6
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2answers
261 views

How many fields is too much for a primary key?

I am creating a table to store information about the placement of objects in a grid (game map). For example, I have a 10x10 grid and I want to store, in the database, that cell (5,5) has a blue box, ...
6
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1answer
1k views

What should every DBA know? [closed]

As a SysAdmin who "wears all the hats", I find myself increasingly pulled into database projects. I took one database course back in college and since then I've always scoured resources online (like ...
6
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2answers
2k views

How to implement soft deletes?

What is your method of implementing soft deletes in a database? Ideally the solution would allow for decent performance on large tables take relationships into account take unique keys into account ...
6
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3answers
607 views

Representing N:N relation as a functional dependency in a database design

As a software developer, I already have some experience in designing a more or less normalized database schema, but I haven't received any formal training in it before. This semester, I took a ...
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2answers
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Allowing Foreign Key to be Null

I'm trying to create a relationship between two tables where one column in TABLE A is the foreign key for a column in TABLE B. However, there is one row in TABLE B that is currently null in that ...
6
votes
2answers
1k views

How can I save a severely fragmented database/table?

I've recently made a discovery that might explain my slow SQL run times. I found out that the default in SSMS is to allow mdf growth of 1MB at a time. When the size of one table alone is roughly 23 ...
6
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1answer
194 views

Use multiple columns for location or supertype/subtype?

Given an Equipment entity, it has a location, generically called Whereabouts. This could be a reference to: a User entity (the employee who will use and be responsible for the eqipment for the next ...
6
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1answer
358 views

Dimension Help - Deciding Fact or Dimension

We have the following Dim and Facts: Customer Dim: SCD Type 2, Info about the customer ie first purchase date, name, address, etc Product Dim: SCD Type 2, about our products Customer Snapshot ...
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356 views

Definition for “logical difference”?

I'm currently reading "SQL and Relational Theory" by C.J. Date. And although I'm quite far in the book, I've got a few basic questions. I want to know what the term "logical difference" means, The ...