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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Per person weighted answers

Hi I'm new to database design but am trying to make sure I get things right first time so as not to pick up bad habits. My question is I have a set of people for which I want to record needs mapped to ...
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How should I model an “either/or” relationship?

Say I have an entity named Software and two sub-types FreeSoftware and NonFreeSoftware. The NonFreeSoftware entity has attributes such as purchase date, vendor, etc.. The FreeSoftware entity has ...
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2k views

Bit vs. Boolean columns

Given that bit fields are just binary representations of data and need to be queried in slightly "strange" way. Does it actually provide any benefit using a bit field for a boolean value? From what I ...
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How do I add a time dimension to this forecasting database without having to duplicate every data point @ each reforecast?

I have a database designed to facilitate revenue forecasting. Revenue forecasting consists of tracking Orders which are recognized into Revenue at multiple points in time (each, a revenueDate). There ...
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1answer
106 views

Possible pitfalls of condensing 2 SQL Server instances into 1

I currently have 2 SQL Server 2000 database instances (each running on a different physical server), each containing around 12 databases (not all are active). We are planning an upgrade to SQL Server ...
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2answers
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Sporadic execution time causing timeouts [closed]

We have a table with 100 million records holding 24 hour worth of data of our clients' customers actions (actions which are performed on 3rd party sites and replicated from there to our server) The ...
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581 views

financial transactions with and without commissions

I'm building a gambling website. All financial transactions from and to external sources (credit cards, money transfer systems) are subject to commission. Amount of the commission depends on the ...
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1answer
468 views

How does PostgreSQL physically order new records on disk (after a cluster on primary key)?

Need to know how PostgreSQL orders records on disk. In this case, I would like to take advantage of index combination as stated in the docs, which as I understand uses bitmaps to get matching rows ...
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1answer
827 views

Does PgBouncer create a separate pool for every database config entry?

If I set up a pgbouncer.ini config file with several database entries, does pgBouncer create a separate pool for each one? I would think so, but have not been able to confirm this. For example, ...
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Relationship that are optionally more specific

Forgive my title, I couldn't think of anything that accurately describes what I'm talking about. I currently have the following relationship. CREATE TABLE Events ( ID INT IDENTITY(1,1) NOT ...
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2answers
999 views

Choosing MyISAM over InnoDB for these project requirements; and long term options

Sorry for the long post, but I had to give as much info as possible to make this very vague question more specific. My project's aim is to let users search a (huge) database of variety of products. ...
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Partitioning a table vs moving entries to another table

I don't understand how partitioning helps me more or less than using a separate table to store older records. I need to maintain a list of stock entries along with historical records about the stock. ...
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How to store many smallish time-series in a relational DB?

Input Data Multiple Tests Beds generate measurement data of various complexity. In it's most basic form, not considering any meta-data, one measurement on a Test Bed will be a small (1 - a few ...
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How should an object that can reference an object of multiple types be modeled in a relational schema?

Apologies for the obscure question, it may make more sense with a concrete example: In my application, I may create a portfolio that contains a set of projects. However, I may also add a ...
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Design for storing data only applicable to a small subset of records

So my boss and I are in disagreement how to best design our database for storing miscellaneous data for certain clients. Basically, we have a bunch of tables in some format similar to this (in ...
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How to design a schema to store search keywords

I am doing a database design that stores search keywords of a search form, used to generate the most popular search keyword reports by date, month and year. I have made a simple schema: CREATE TABLE ...
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1answer
496 views

Can filtered indexes help improve queries that are based on a time entered or should this be avoided?

I'm just learning about the new filtered indexes in MS SQL 2008 and I'm trying to understand where they would hurt and where they would help. I can see that adding a filtered index to an employees ...
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1answer
124 views

Many-to-many relationship with attributes

I'm working on a project where I need a book database. The problem is as follows: A book can be related to multiple people (authors, editors, traslators, etc.). Then a person may contribute to ...
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How to enforce the structural constraints of rectangularly arrayed data?

(I'm particularly interested in answers that view the question below as a special case of the question: how should a RDBMS enforce structural constraints that are more specific than "one-to-many" and ...
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648 views

Enforce data integrity with a recursive table

I have an existing oracle 11g database schema that works with a web application. I am planning an expansion to the application so a web service can do data operations on the database. As part of the ...
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613 views

How to properly configure PostgreSQL RAM usage?

Using PostgreSQL, we have several hundred concurrent processes doing regular database access. We have our data spread out through several database servers, each of which houses a connection pool with ...
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1answer
93 views

Database Design: Linking 'vague' entries to associations?

Experienced developer, inexperienced DBA here. I'm currently working on a project that lets users input the names of freight vehicles for particular packages. Eg: Company: White Star Line Vehicle: ...
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Survey database design: first version. Are there errors?

I have to represent surveys with questions like these ones: Studying those groups of questions I found these rules: A survey has questions' groups. A questions' group has a name and questions ...
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how to enable temporal database capability in mysql.?

How to enable the temporal database compatibility in mysql database? Is there any library or a plug-in to enable the temporal upward compatibility? I want to keep the past records whenever a current ...
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354 views

HStore vs. multiple tables with inheritance - do I have a good use case for HStore?

My broader question here has to do with when it is appropriate to use HStore vs. multiple tables vs. one table for storing document-like objects. Now, for my localized example: I’m designing a ...
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3k views

Could too many idle connections affect PostgreSQL 9.2 performance?

Some queries on my database server seem to take a long time to respond, and I believe the CPU usage is high. When running ps aux, I see ~250 "idle" connections (which I believe to be too many). I ...
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155 views

To Foreign Key or not to Foreign Key… (inet -> cidr)

Below is a very abridged version of a project I am working on. CREATE TABLE cidr_block ( id serial not null unique, block_def cidr primary key, dhcp_server_id int not null references ...
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Partition pruning with multiple date columns

I have a large table in Oracle 11g database that holds historical data from several years, so I would like to partition it by year. The problem is that the table has multiple date columns and they are ...
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Vehicle spare parts inventory datadase model

I am modeling a database to be used for vehicle spare parts inventory management and I am stuck... Some spare parts can be broken down from a kit into component parts. I would like to create a model ...
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1answer
385 views

Design for file based with many events

I'm not a database guy but I need to design a database to store events for our application. Our client app connects to remote hardware and syncs count data. The count data are csv files split into ...
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718 views

How to handle “reference tables” in CouchDB?

What's the best way to handle "reference tables", tables that contain static data, for example a list with various kinds of ingredients for food? Multiple documents, one for each ingredient One ...
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768 views

In MongoDB, is having lots of small collections better than having one huge collection?

Huge collections have huge indexes that may not fit into RAM. Is that problem entirely solved with sharding ? If I have lots of small collections with small indexes, what are the options for storing ...
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1answer
983 views

Designing a database for a site that stores content from multiple services?

I'm building a site that implements David Allen's Getting Things Done that pulls in your email, Facebook newsfeed, tweets from those you follow on Twitter, and more services are planned. The problem ...
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Should you ever not assign an unique ID to each row in a table? [duplicate]

Possible Duplicate: Should every table have a single-field surrogate/artificial primary key? I can't imagine ever not using a unique ID with every table, which is why I'm asking this ...
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Efficient way of changing VARCHAR to NVARCHAR fields in a large table in SQL Server 2008?

I am aware of when adding new fields to large tables, it is recommended to add them to the end of the fields rather than somewhere in the middle, and wondering if something like this applies when ...
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6answers
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Any way around unique index 16 column max

According to the CREATE INDEX documentation: Up to 16 columns can be combined into a single composite index key. We've got a table with ~18 columns that need to form a unique combination. This ...
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3answers
689 views

Is a surrogate key better than a natural key in this case

I copied this code from here: CREATE TABLE records( email TEXT REFERENCES users(email), lat DECIMAL, lon DECIMAL, depth TEXT, upload_date TIMESTAMP, comment TEXT, PRIMARY ...
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1answer
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PostgreSQL versus MySQL for EAV structures storage

Is there any practical difference or what are the advantages of using Postgres 9.x versus MySQL 5.x for storing EAV (Entity-Attribute-Value) structures, especially in terms of read performance?
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Database Design Issues

My question consists of three parts: When can I be sure that my database design is perfect? Is returning to the database design to change some issues (i.e, adding new column, deleting a column, ...
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5k views

How to choose a collation for international database?

I'm designing a database which will store data in different languages (using UTF-8), so I think the best way to display the queries results is ordering it according to the user's language during the ...
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Create table group sub-folders in Management Studio

When I was exploring the master database in SSMS I noticed that under the Tables folder there is another folder called Systems Tables that houses a bunch of tables. Is it possible for us to create a ...
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How to export an ER diagram from an Oracle DB?

I am developing this application with an Oracle database. I haven't been documenting the data model, but now an auditor wants to have an entity relationship diagram of my database. There are many ...
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Ready-to-Use Database models example

Where can I find ready-to-use database models ? I don't need a database with data in it, but only schemas (UML diagrams). Perhaps something like the data models at this link, but much more complex ...
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362 views

DB Optimization with 2 to the power of N - Approach clarification

This is a request for analysis and better performance approaches, one of my colleague has come up with an approach in optimizing the DB and it looks very impressive too. Can someone please let us know ...
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4answers
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Examples of SQL transaction procedures for sales tracking or a financial database

I am making a database for an accounting/sales type system similar to a car sales database and would like to make some transactions for the following real world actions: salesman creates new product ...
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Lookup table for a one-to-many relationship

I have a tickets table with an id that I need to associate to a lookup table where the counterpart of that data is another id that is controlled from an outside source. tickets - id - sutff lookup - ...
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1answer
5k views

Product Attribute List Design Pattern

I am working on updating our website's product database. It’s built in MySQL but this is more of a general database design pattern question. I’m planning on switching to a Supertype/Subtype pattern. ...
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2answers
1k views

Data type for currency 'type' column, e.g. usd, cat, etc.

I am setting up a MySQL database for accounting software. One of the fields is to save the currency used for each transaction. What field type would you recommend? Details: No more than 10 different ...
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844 views

Speed problem with a simple select statement

I'm having a problem with a select statement taking way too long to run. I would like to know if I'm doing something wrong or if it taking this long makes sense. I am using Microsoft SQL 2005 ...
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Data validity and accuracy according to database integrity

What does it mean that data is valid and accurate according to database integrity?