The logical model and/or physical design of a database.

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6
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1answer
3k views

What's difference between standard view and indexed view in SQL Server [closed]

I learn that the indexed view holds the data from base tables while standard view does not holds data.Is it means that the indexed view need memory and standard view don't? Indexed view needs to be ...
6
votes
2answers
2k views

Best way to handle dates prior to 1000 A.D. in MySQL?

I am creating a database for records that extend prior to 1000 AD, but MySQL Date and DateTime fields only support dates starting at 1000. Is there a way that would be more convenient than either ...
6
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1answer
20k views

Fixing table structure to avoid `Error: duplicate key value violates unique constraint`

I have a table which is created this way: -- -- Table: #__content -- CREATE TABLE "jos_content" ( "id" serial NOT NULL, "asset_id" bigint DEFAULT 0 NOT NULL, ... "xreference" varchar(50) ...
6
votes
4answers
240 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 ...
6
votes
1answer
760 views

Convert clustered primary key to non-clustered and use another column for the clustered index

I have a large table with a primary key (GUID) that is also the clustered index. There is already a integer sequence based field. So I want to leave the GUID as the PK and make the integer column the ...
6
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2answers
4k views

Index max row size error

Is there a upper bound for an array column? I am getting this error when inserting into the array field - PG::Error: ERROR: index row size 3480 exceeds maximum 2712 for index "ix_data" Here's my ...
6
votes
1answer
5k views

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
votes
2answers
689 views

Table contains multiple names for same company

I have a table of monetary transactions that has a field for who the money was paid to or received from. Transactions are recorded using info from paper invoices, paper reciepts, internet reciepts, ...
6
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2answers
219 views

Efficient Database schema for multi-lingual content?

Assume I have a table for blog posts, posts, and schema as id author title content and each post can belonged to some categories id name descrtiption So a blog post can belong to multiple ...
6
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3answers
477 views

Need help on my first ER diagram

I just started my first Database course online, and I have a homework assignment to create an E-R diagram from a list of specifications. The specs are as follows: The company is organized into ...
6
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2answers
537 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
990 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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2answers
333 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
votes
2answers
2k views

Recommended model for application level event logging

I am going to be storing application level events (user A added thing, user B updated that etc) for both public and private consumption. Below is an oversimplified model of the tables and their ...
6
votes
1answer
801 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
votes
2answers
2k views

Unknown Db file format - best way to find out?

A client has given me the data he wants visualised in my project - but I don't know what DB format it's in. He's pretty unclear, also.. I have access to the table structures, but don't know how to ...
6
votes
1answer
1k 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
votes
2answers
502 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
votes
2answers
4k views

Which datatype to store XML data in: VARCHAR(MAX) or XML

I am defining a schema for a new set of resources using SQL Server 2008... In this case, each record (e.g. row) will need to store XML fragments. From time-to-time; although not frequently; I'll need ...
6
votes
3answers
1k views

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
votes
1answer
84 views

Is my implementation of type/subtype design pattern (for mutually exclusive subclasses) correct?

Introduction In order for this question to be useful for future readers I will use the generic data model to illustrate the problems I face. Our data model consists of two entities, which shall be ...
6
votes
3answers
538 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
1k 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
484 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
votes
1answer
3k views

need suggestions to improve view performance

I am looking to improve the performance of a view in SQL Server 2008. This view exists in a reporting database that is widely used by not-very-technical-folk to basically denormalize all of these ...
6
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2answers
784 views

How should I best design the tables and relationships, given the following rules?

In a Pawnshop business, customers pawn, sell or buy items. A contract which specifies the customers information, the items, and the terms and conditions is created whenever customers pawn, sell or buy ...
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2answers
4k views

free database modelling software [closed]

What is available in the realms of database modelling software that is free. I am developing an SQLExpress database. CA ERWin - community version although is free, I can't see an option to allow ...
6
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2answers
3k 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
votes
1answer
8k views

Ternary relationship: what's the difference between having single table and having multiple tables?

Consider the following ternary relationship: Suppose that all entities have only two attributes (PK and Name). Here are the tables I derived (5 tables): Sector ------------------------- ...
6
votes
1answer
762 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 ...
6
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1answer
2k views

EAV structure explained in Layman's terms

I've read several articles online that explain how EAV structures work, but there are different interpretations of them. Some articles mention that it's a representation of a data model metadata (or ...
6
votes
2answers
2k 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
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
votes
3answers
878 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 ...
6
votes
1answer
161 views

PostgreSQL and table inheritance

I'm not sure if this is the right place for this, so please feel free to tell me if it is off-topic or there is a better place to post. I am working on a fantasy sports based project, and the number ...
6
votes
2answers
2k views

Will table inheritance in PostgreSql suit this situation?

Let's start off by saying, I'm new to PSQL and coming from a MSSQL background. I'm starting to design a DB in PSQL. So my main aim is to have a Main schema in this DB, which I am going to use to ...
6
votes
1answer
2k views

SSIS package with BULK data load

I analyzed a C# program over the weekend for a customer that basically does the following: Truncate Table Fetch Data (source on these is either remote database or local database where job runs) ...
6
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2answers
13k views

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
2k views

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 ...
6
votes
1answer
213 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
votes
1answer
393 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 Fact:...
6
votes
2answers
480 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 ...
6
votes
1answer
503 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 ...
6
votes
2answers
149 views

Creating relationships between tables that where not specified in the given UML diagram

Good evening! I'm working on designing my very first actual database from the following UML class diagram (in French unfortunately): I'm at the point of creating the relational sketch of it which ...
6
votes
1answer
5k views

Database design: Two 1 to many relationships to the same table

I have to model a situation where I have a table Chequing_Account (which contains budget, iban number and other details of the account) which has to be related to two different tables Person and ...
6
votes
1answer
2k views

Pros and cons of using many schemas in PostgreSQL as opposed to just one?

For a large SAAS application (backed by PostgreSql 9.4), with over 300,000 accounts (and growing), what are the pros and cons of using a schema per account to partition the data vs putting all the ...
6
votes
1answer
192 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 ...
6
votes
1answer
398 views

Hierarchical structure with limited number of records per user

I am planning schema for an affiliate network. For all hierarchical queries I am using Postgres tablefunc extension but here is another problem. Any user can refer only 3 other users at max. So for ...
6
votes
1answer
7k 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 ...
6
votes
2answers
4k views

Bitmask Flags with Lookup Tables Clarification

I've received a dataset from an outside source which contains several bitmask fields as varchars. They come in length as low as 3 and as long as 21 values long. I need to be able to run SELECT queries ...