A schema of a database system is its structure described in a formal language supported by the database management system (DBMS) and refers to the organization of data to create a blueprint of how a database will be constructed (divided into database tables).

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Query across multiple schemas, unknown until execution time

I have multiple schemas that I need to query across. The schemas are not known in advance, for example: U111 U222 U333 I need to select across these three schemas from a specific table in each of ...
5
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2answers
505 views

Searching 500 million records of binary data

I will inserting into a database the signatures of 500,000,000 pictures. The signatures will be generated using libpuzzle. Each signature is 338 bytes. (so 160 GB) plus a table for searching (read ...
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81 views

Do supertables produce bottlenecks?

There are several alternatives to using polymorphic associations and one of them is to use the so-called "concrete supertable". From my point of view, this is the neatest solution and is pretty easy ...
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1answer
432 views

How can I Automate MongoDB schema design from existing MySQL Database and Logs?

I am working on the project which will automatically generate sample MongoDB schema analyzing existing MySQL database and logs. I am looking for help regarding the below questions. Please, share your ...
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53 views

Multi language where this feature never existed

I need to implement multi language system in an existing system that was not developed for this. The number of entries in the tables that will hold data that has to be translated will not exceed 5 ...
2
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1answer
442 views

Is there any way MySQL can list relationship cardinality between two entities?

I am working on the project where I have to analyse the MySQL schema. As a part of schema information, I want to list down relationship cardinality between different relations. Does MySQL stores ...
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2answers
2k views

Dynamically change schema to accommodate custom fields!

I am working on building a sort of a cms for a particular project. Nothing that will have a large volume of records in any table. Within 6 digits max. I was thinking to create the default schema for ...
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2answers
203 views

MySQL 5.5 to 5.6 Upgrade. Will data remain the same?

We are considering to upgrade to MySQL 5.6 this summer. I would like to know if our data will be changed in any way once we perform the upgrade? I've been reading and I found that mysql_upgrade ...
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0answers
333 views

Review a database schema for a design approval system

I'm working on my first web application that will utilize a database. The basis for the application is a design approval system. I work for a company which mainly produces print and online marketing ...
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1answer
838 views

MySQL DB structure with Main category and several nested sub categories

I am looking to create a set of fields on my webpage identical to what eBay uses on their category selection page when you are selling something. For my purposes I am doing motorcycles, power sports, ...
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3answers
11k views

What is the difference between logical schema and physical schema?

While going through Database architecture I came across Schema's . I am very much confused with: Logical schema Physical schema How these two schema exist in the Database? How can these be ...
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1answer
168 views

Help With MySQL Computed Columns/Auto Updating Field Based On Average

I am currently building a social network type application on-top of MySQL and have run into a problem I can't wrap my head around. In my web application each user has a field called "weight" and this ...
3
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1answer
188 views

Help with “Flexible” vs Fixed Tables

We are designing a database in SQL Server to handle sales commissions. A diagram of the current schema looks like this: There are only a couple of us on the project, and our boss dropped this ...
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338 views

Lossy Decomposition meaning

Suppose I have a relation R=(A,B,C,D) and I decompose it into: R1=(A,B,C) R2=(A,D) then if it is said that the decomposition is lossy,then what is the meaning of that statement?I have an ...
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2answers
147 views

Does this medical database look correct?

I'm pretty new to databases and I'm trying to create some schemas. I've been working away at this one for a while, but I can't help feeling that it doesn't look right. Essentially I have the ...
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1answer
508 views

Can I alter a view being referenced with schemabinding if the change fulfills the binding requirement?

In SQL Server 2008, I have views WITH SCHEMABINDING and I need to alter one. I am changing a column while not changing its alias so consumers will be unaffected. If I were to drop all my other views ...
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0answers
72 views

How should I restructure a table that contains multiple columns that contain similar, but not same data?

I currently inherited an InnoDB table that describes a product. In the table there are a few columns that describe the maximum height at which the product may be mounted. These are the columns: ...
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2answers
1k views

Designing database with Category and Tags for Posts - Seeking for guidance/advice

I'm not really a database novice but I'm not an expert either. Problem: I'm having this difficulty on designing my Post, Category and Tags relationship. I've read Normalization many times but could ...
3
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2answers
253 views

Is there a well-known name for this “poor man's ref. integrity” schema design pattern?

Is there a name for the following database schema design/pattern? My eventual goal is to find more literature about the subject. Today's cursory net search was too full of generic words to be able pin ...
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4answers
2k views

eCommerce orders table. Save prices, or use an audit/history table?

Im designing my first eCommerce schema. I've been reading around the subject for a little while, and am a bit confused about the relationship between an order_line_item and a product A product can ...
0
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2answers
144 views

Schema for lists of relationship differences

Say there is a data model that allows for relationships to be defined either explicitly or as a list of records added or removed relative to some existing item: Item <–> *Properties and Item ...
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0answers
134 views

MySQL Workbench Forward Engineer from only the current diagram

I want to create a test database from a huge schema in MySQL, but when I try to do Forward Engineer from a Diagram with about 6 tables, it try to create all the tables, views and routines groups that ...
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0answers
407 views

MySQL Space efficient way of storing indexed key-value pairs associated with table

We're storing transactions in an accounting system using two tables, one contains the general description of the particular transaction (the other contains the entries, one for each account - which ...
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1answer
160 views

Scheme review/Normalization level/query optimization

So I have a relatively complex database I'm designing - basically full in-house accounting setup. In one section I have some concern that I'm over-normalizing; the 'directory' - I'll example the ...
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2answers
58 views

Best design for a many:many relationship issue

We have three types of entity, each with their own table: table:A(a_id), table:B(b_id), table:C(c_id) Each of these entities can have any number of email addresses and linked Twitter accounts. ...
2
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1answer
205 views

Relation between multiple hierarchical taxonomies linked to a single entity

I am working on an online test application which supports multiple choice questions. I have created schema for taxonomy (classification) system to be used with questions. taxonomy(id, name, slug, ...
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1answer
339 views

Automatically generate ALTER TABLE to syncronize schema on PostgreSQL

i Have 2 different database schema in PostgreSQL sql file from pg_dump, is there automated way to generate alter table commands so it would be in sync, without inspecting one by one? this is the ...
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1answer
268 views

Do I need to explicitly grant permissions for a login under the sysadmin role for it to access a custom schema?

So I have a login that has sysadmin rights on the db server. However, it's not able to access database objects under a custom schema that was created (eg. it cannot select from tables with ...
2
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1answer
514 views

Should I save “document ID” as a String or Number in MongoDB

So I'm importing about a 100,000 documents into mondoDB. MongoDB already generates an Object hash but the data has a documentID that was used to identify records in the previous database. The IDs ...
0
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1answer
527 views

Shopping cart schema with multiple product tables

I have a shopping cart table used to store customer id and product id of their chosen items. However I have multiple product tables, for example cars, books, houses. I started out with one table but ...
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1answer
98 views

Multi tenancy by schema - Deny access to another tenants [closed]

In a multi tenant environment, where the multiple tenants are in the same database and a schema is used to separate each one of them, how can I create a database user (MS SQL SERVER) for each schema, ...
1
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1answer
130 views

Schema for yearly data models

I am developing a school management system. Most data will not be reused after the end of the school year. I am contemplating using schemas to separate data in various school years, however I am ...
2
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3answers
554 views

Database design for bookmark system

I am creating a bookmark system where people can save their bookmarks. Each user has its own personal page with bookmarks. A bookmark should have atleast one tag and max five. Each user can create ...
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3answers
1k views

Is it bad idea to create foreign keys on the tables in a different schemas in the same database for big applications?

I am working on the transfer a big pl/sql web-based application to the dedicated server. This application is located in one schema with 70 packages of programm code. This application was made ...
0
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2answers
87 views

Store extra, optional information about any entity [closed]

I've done a bit of reading but haven't found anything related. This must be widely discussed, so it's most likely my fault. I've got a relational database with a number of different tables, each ...
1
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1answer
662 views

Polymorphic Association - is it bad? [duplicate]

In the following schema: Collections Upvotes Reports Upvotes Reviews Upvotes I'm tempted to have a single Upvotes table with a single "entityId" column that stores either the ...
5
votes
1answer
2k views

How to migrate between schemas in bulk in SQL Server?

We currently have multiple databases but would like to combine them and, instead, separate our domain contexts using schemas. In MS SQL Server 2008 R2, how can I relocate all the contents of one ...
0
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2answers
206 views

Accept null value on parent column in multipart relationship

EDIT: I've come up with one poor solution (below) that requires some denormalization, but does avoid the risks of UDFs in CHECK constraints. I would appreciate your help if you have a better answer. ...
2
votes
1answer
127 views

To normalize or not to normalizde? (10 fields)

I'm helping someone to design a database and for a specific case I'm not sure. I have 10 fields - this will never change - that will always be filled and used in every query that could be coming up. ...
2
votes
2answers
760 views

How to create a blank version of a PostgreSQL database

I've been using pgAdmin to create a database and test it. I'm at a point now where I need to install this db on different servers. I've been using pg_dump to do this and I've been able to muddle my ...
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2answers
625 views

Postgres sequence usage

I have an Postgres database with two users: dev and junit. Junit and dev objects are dropped and created regularly. They both have the same objects unshared for tables, however, sequences are shared, ...
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1answer
727 views

How To Hide Schema from user

I have DB with 2 schemas: A and B. B schema's procedures use A schema's procedures. I need to create user, which will not be able to see A schema. This user can use only B schema, but i want to let ...
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0answers
103 views

Cloning Postgres schema/tables across multiple servers

I'm working on a project that has databases across multiple servers, with one server for each business client. The project has some identical 'base' tables that are present in all the databases (for ...
1
vote
1answer
4k views

How to transfer the ownership of the dbo schema in SQL Server 2012

I've accidentally given a user the ownership of the db_owner schema (using the check box in the UI as below) and now I cannot: Transfer ownership to another user Drop the user from DB (though I can ...
1
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2answers
404 views

Oracle - Is it possible to maintain transaction across multiple schemas?

I got this database in oracle which includes 4 schemas. Each schema represents a logical layer. Each transaction (Stored Procedure) in the upper layer breaks into a couple of transactions in the lower ...
1
vote
1answer
488 views

Easier way to change every user in every database to default schema = dbo?

There was recently a domain migration where our SQL Server is hosted. I have two servers and about 30 DBs on each. Every user was changed to the new domain but in doing so, their default schema ...
1
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1answer
245 views

Should I extract / normalize the mailing address despite requirements limiting number / type of addresses?

I currently am working on a contacts application (similar to Outlook contacts combined with eVites and LinkedIn). The requirements for the application are to limit the addresses (and phone / email ...
0
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1answer
284 views

Data Sync between servers with different schema in SQL Server [closed]

I have two servers 2008 R2 and 2005. The e-commerce site has been running with 2005 Server. I have migrated 2005 server data with modified data schema to 2008 R2 from yesterday's date of data. My ...
2
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3answers
495 views

Many to many link tables with history? [closed]

While creating a PostgreSQL database of customer subscribed services with DNS domains, I want to: enable customers to subscribe to multiple services each service can have multiple domain names per ...
-2
votes
1answer
261 views

message table schema - body TEXT or varchar [closed]

I want to make a small social network. For messaging body which one is more suitable? VARCHAR or TEXT? if VARCHAR how long is efficient?