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Questions tagged [database-design]

The development of the conceptual schema and/or the logical model and/or the physical settings of a database.

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Foreign Key with a Constant

Let's say I have a table A, that has two columns: one is an ID for ThingA, and one is an ID for ThingB. The primary key is (ThingA, ThingB). Next, I have a second table, but this time it's restricted ...
7
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0answers
11k views

Conceptual data model for a billing system

I am working on existing MySQL database. My task is to create a new data model for a billing system on that existing application. I have created a conceptual data model (click to enlarge): ...
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0answers
1k views

Working on a decision tree database design

I'm doing the conceptual model for a Decision tree database. The goal is store any Decision tree. I have four entity types: DecisionTree, Node, Branch and Leaf. Each Decision tree is composed of ...
5
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1answer
2k views

ERD for a web development company

I am working on an ERD which represents the relationships between entities in a Web development company behavioral model. There I have entities like: Customer Service ----------- (like: web ...
5
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0answers
136 views

Database design for ~ 2.7B rows per year / 26.000 data points every five minutes

The current situation We're currently looking into a new product that will send device data back to us to interpret. These are the numbers we're looking at: Devices will most likely send data every ...
5
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3answers
110 views

Optimizing table/indices for getting the latest row (filtering by one additional column)

I have a SQL Server table (SQL Server 2012 SP3 Standard edition) that stores a bunch of configuration information (basically text blobs) for different organizations. The schema is something like this: ...
4
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2answers
132 views

Solving supertype-subtype relationship without sacrificing data consistency in a relational database

Trying to get better at designing databases, I noticed I'm always stuck trying to solve variations of the exact same problem. Here is an example using common requirements: An online store sells ...
4
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0answers
91 views

Can the Chase test algorithm only modify attributes on the right side of a functional dependency?

I'm attempting to apply the Chase Algorithm to determine if a decomposition is a lossless join decomposition. Functional Dependencies = {A → C, B → D, C → D, DE → C, CE → A} Here is my initial ...
4
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1answer
100 views

Should I declare one or two tables to represent Items and Sub Items?

I'm facing a dilemma in my database design for an upholstery store. This store cleans carpets, pillows, car seats, car trunks, couches. There are chairs and sofas with fixed and removable seat ...
4
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1answer
338 views

Tables for Product Components AND Component Combinations

I have a basic understanding of relational databases and would like to assign a number of attributes to an assortment of products. Products examined consistently have four components: model, fabric, ...
4
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4answers
5k views

How can I model a medical scenario in an entity-relationship diagram?

I am a self-taught frontend developer that is trying to go full-stack, so I am trying to teach myself data modelling by means of working on some exercises out of a database management book. In this ...
4
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2answers
1k views

Two ways to define may-have-a (1..0-1) relationship

Today I have discovered for myself that may-have-a, one-to-zero-or-one, (1-0..1) relationship can be implemented in two different ways. Let A be the "main" table (left side of ..) and B be the "...
4
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2answers
78 views

Best db setup to accomplish yes/no list of clients for daily calls

I will preface this by saying I am a relative novice to Access but I have managed to develop some basic databases. I have some working knowledge of expressions and macros but VBA is still a bit of a ...
4
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2answers
57 views

Snooping-safe Vote tables

I have a table with both user_id and vote. They are stored together so each user can only give one vote. However it's also problematic because admins can simply read who voted what. Is there a way to ...
4
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0answers
963 views

How to properly configure pgBouncer transaction level pooling?

What is a good way to determine the number of available transaction connections when using pgBouncer to pool database connections? Also, how should I determine the number of max_connections and ...
4
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0answers
225 views

Database describing databases and references to tables

Context The company I work for makes a number of different softwares each with its own database. As they're all about related things (accounting) a good amount of data is theoretically the same among ...
4
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0answers
1k views

Dynamic MySQL partitioning based on Unix Time

My DB design includes multiple MYISAM tables with measurements collected online, Each row record contains auto-incremented id, some data and an integer representing Unix time. I am designing an ...
4
votes
1answer
677 views

Should I snowflake or duplicate it across my facts?

I'm building up a data warehouse to be used by SSAS to create cubes on, and I'm debating between two possible schemas. In my warehouse, I've got two different fact tables that tracking daily changes ...
3
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0answers
56 views

Versioning rows in a table

So I have this concept in my head of "immutable" records, which I am sure is not novel, but can't seem to find the right google keywords. Basically, historical row values need to be preserved as '...
3
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1answer
188 views

PostgreSQL most efficient way to reference multiple tables

I am looking for the most efficient way to reference multiple tables in one table, when there is only one reference possible at a time. Which means tables A and B are referenced by table C, but both A ...
3
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0answers
82 views

Third Normal Form (3NF) Decomposition Scenario

I am trying to understand what are the steps to check if a decomposition of table is in 3NF. There is a specific exercise I'm trying to solve with no success. Given that R={A1,A2,A3,A4} and F={A1→...
3
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0answers
65 views

How to efficiently store 672 bits of information in PostgreSQL

I have a requirement that needs to store lots of bits and it's actually a time setting for every 15 minutes in a week (indicating if a user is free during that time). So for one day we need: 60 ...
3
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1answer
49 views

Ensuring Uniqueness Across Columns

I'll lead with this: Perhaps the database design is wrong, so I will accept a re-design as a solution! Consider the following table: ID | TypeA | RefA | TypeB | RefB -- + ----- + ---- + ----- + ---- ...
3
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0answers
258 views

Storing a symmetric matrix in postgresql

I have several matrices of distances between objects, like this: Method 1 A B C D ... A 0.0000000 . . . B 0.5458965 0.0000000 . ...
3
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0answers
33 views

How to design a database for my entity-relationship diagram about Projects, Tasks and Developers

I'm new to database and my entity-relationship diagram is as follows: According to that I designed my SQL-DDL database statements as shown below: CREATE TABLE Developer ( DeveloperID int NOT ...
3
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2answers
7k views

Grouping data into 5 minute intervals within a time range

I am trying to prepare data for a candle stick chart. I have some records on MySQL database as shown below: | Rate | Date | |----------|---------------------| | 0.001111 | 2017-11-...
3
votes
1answer
540 views

Why do OLAP cubes perform better than Relational databases on certain tasks?

My team uses a Multidimensional OLAP database for a lot of it's analytics and predictive modeling. The standard line in all the documentation is "OLAP cubes are better suited for this type of ...
3
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0answers
110 views

Modeling a database structure for a trip management business domain

I am sketching up a database design and it is giving me some troubles. Basically something just "smells" about this design but I can't seem to arrive at a better way to do it. For example, the Joins ...
3
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2answers
721 views

Table design for “Users & Groups” plus “Groups within Groups”

I need to represent users and groups, where groups can be nested within other groups. (Not my design choice – I am replicating another system and must mimic this behavior. I have no access to its ...
3
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0answers
2k views

How do you perform the chase test?

Trying to follow the chase algorithm as I understand it, If two rows agree in the left side of a functional dependency (FD for brevity), make their right sides agree too. Always replace a ...
3
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0answers
756 views

Serialized Inventory Tracking

I'm developing a inventory system with optional serial no tracking (which users can turn on for items they select). in order to keep stock records currently i came up with two options. Option 01 use ...
3
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0answers
501 views

Which SQL Power Architect type to specify for [PostgreSQL] UUIDs/GUIDs in new column property template/UI?

I have inherited maintaining and extending SQL Power Architect projects in source control which are used to generate the DDL for project DB schemas. We are currently using PostgreSQL 9.5 and SQL Power ...
3
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0answers
846 views

Supertype table with disjoint subtypes in MySQL

I want to have base parent table with few disjoint subtypes. To illustrate what I mean: CREATE TABLE issues ( issue_id SERIAL PRIMARY_KEY, issue_type CHAR(1) CHECK (issue_type IN ('B', 'F')), ...
3
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0answers
151 views

Conceptual Diagram advice for varying Product and History states

AIM: A MsSQL DB to hold Products / services that will vary significantly, although there won't be many; hence, the N:N attributes for ProductTypes. Be able to keep a record of Product changes [Price, ...
3
votes
1answer
55 views

When to create a new table if functionality is the same?

I am having trouble making database schema/design decisions. The database I am building is relational. Consider this example: I have these tables: orders, products, companies. I want to create ...
3
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0answers
637 views

How to model a price discount with a purchase of several products as condition?

Scenario Let us say that, in my business context, there are three different products, i.e., product one, two and three, and I wish to offer price discounts when a condition like the following one ...
3
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0answers
266 views

Is it good practice to have multiple keyspaces in Cassandra?

I've Cassandra configured on Amazon EC2 having 3 nodes(instances) in single cluster. Now what I want to do is give some space on Cassandra to my clients by creating separate keyspace for each in a ...
3
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0answers
414 views

Anchoring values for a rating or likert scale

I am designing a schema for an interview system as per the suggestion in this answer. I need to store several different types of questions: Questions with a free-text response Multiple choice text-...
3
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0answers
217 views

Inputting auto-incrementing, grouped, unique hashes?

Alright, here's what I've come up with so far: SET @id=(SELECT IFNULL(MAX(id) + 1, 0) FROM leads); UPDATE leads SET id=@id WHERE id IN ( SELECT id FROM (SELECT * FROM leads) AS something WHERE ...
3
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0answers
349 views

Database Designs Alternative to Polymorphism in Establishing Relationships

I'm working on a database which handles replacement of parts in a machine. Rules A machine has many components A machine has a set of assembly instructions Many components have many part (screws, ...
3
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0answers
239 views

Could I use both UUID and Sequential ID or is it bad design

Sequential IDs have pros and cons. UUIDs have pros and cons too. Why not use both for each table? (Let's say I have -and will have- no problem about storage space) I could use: UUID for exposition, ...
3
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0answers
792 views

Personal Finance database review

G'Day, I found that someone had started on this topic on personal finance, I like to go further using a good personal finance plan I found on the internet which I would model. In advance please ...
3
votes
0answers
762 views

ERD for a Contract between a Writer and a Publisher: Is it correct, can it be simpler?

I created an entity-relationship diagram (ERD) for a book publishing business context that I will detail bellow. Entity types The entity types of interest are: Writer Work (as a book) Publisher ...
3
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0answers
104 views

SQL Server storing predefined value sets along with open values

I have Cars with different Characteristics, Characteristics have values, which can be restricted by predefined set of values or be "open" values (any string). Characteristics and predefined values ...
3
votes
0answers
121 views

How to relate a “parent common” table with its (possibly many) “subtype” tables?

I am having a bit of a brain freeze. I have a table whose properties are the root of four distinct elements, for example: I need to relate SystemType to a SystemCommon, where one SystemCommon can ...
3
votes
1answer
63 views

What process would you use to determine references on a database that has no integrity?

Imagine you inherit a database which has a bunch of tables, no documentation and zero referential integrity. Now you're trying to find out what are the various relationships between different tables. ...
3
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0answers
76 views

why some one will use approximate data types for sales

I was messing around with Kartris online shop and I was reading this definition for a product version(you have basic information of a product in one table and many versions of products wich can have ...
3
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0answers
470 views

transaction replication causing too many deadlocks after adding a indexed view - what to monitor in order to avoid this?

I have created the following indexed view and its clustered index: This view was created on a subscriber database and all the tables used in the view are constantly being written to through the ...
3
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0answers
84 views

One table or four?

I have four entities: Absence { ID, StartDate, EndDate, Days, Hours, Reason } Overtime { ID, Reason, Date (Integer), Hours (Integer) } Time in lieu { ID, Reason, Date, Hours } Holiday { ID, ...
3
votes
1answer
117 views

Schema for scarce goods

I have following objects: (Rooms) which are (available in a certain period of time [in days]). During the time of availability they can be (booked) by (users). There are basically these four tables. I ...