New Media and
Technology
New Media (Oracle) Database Design Template
Document Authorisation
Name:
Mike Hilton
Position:
New Media Database Architect
Signature:
Date:
29th April 2003
Document references
Version:
1.0
Date:
29th April 2003
BBC New Media and Technology
1
New Media (Oracle) Database Design Template.
Document Control
1.1 Work carried out by:
Name
Mike Hilton
Department
Infrastructure Cluster
Ext
73988
Position
Ext
1.2 Reviewers
Name
1.3 Document History
Version
1.0
Date
29/04/03
Author
Mike Hilton
Description
First issue.
Any comments or queries about this document should be addressed to Mike Hilton
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Contents
1
DOCUMENT CONTROL ............................................................................... 2
1.1
Work carried out by: ............................................................................. 2
1.2
Reviewers .............................................................................................. 2
1.3
Document History ................................................................................. 2
2 INTRODUCTION ........................................................................................... 5
2.1
Scope, Approach and Methods ........................................................... 5
2.2
How to Review ...................................................................................... 5
2.3
Related Documents .............................................................................. 5
3 SUBSYSTEM/APPLICATION OVERVIEW ................................................... 6
3.1
Architecture .......................................................................................... 6
3.1.1
3.1.2
3.1.3
3.1.4
4
Hardware Architecture ................................................................................................6
Software Architecture ..................................................................................................6
Interfaces ....................................................................................................................6
Datastores ...................................................................................................................6
DATABASE DESIGN DECISIONS ............................................................... 6
4.1
Assumptions ......................................................................................... 7
4.2
Standards Deviations ........................................................................... 7
4.3
Entity Mapping ...................................................................................... 7
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.3.6
4.4
Mapping rules .............................................................................................................7
Entities and Attributes Not Implemented ....................................................................7
Non-trivial Mapping .....................................................................................................7
Additional Objects .......................................................................................................8
Key mappings .............................................................................................................8
Other Deviations .........................................................................................................9
Denormalisation ................................................................................... 9
4.4.1
4.4.2
Performance Improvement .........................................................................................9
Functional Support ................................................................................................... 10
4.5
Journaling and History....................................................................... 10
4.6
Business Rules ................................................................................... 10
4.7
Implied Functionality .......................................................................... 10
5 INTERFACES AND DEPENDENCIES ........................................................ 11
5.1
Interfaces............................................................................................. 11
5.1.1
Interface <Name/Id> ................................................................................................ 11
5.2
Dependencies ..................................................................................... 11
6 REPORTING AND MIS ............................................................................... 12
6.1
Requirements ...................................................................................... 12
6.2
Design issues ..................................................................................... 12
7 DATA ACCESS ........................................................................................... 12
7.1
Role Definitions .................................................................................. 12
7.2
Users.................................................................................................... 12
7.3
Table Access Patterns ....................................................................... 13
8 PHYSICAL IMPLEMENTATION CONSIDERATIONS ................................ 13
8.1
Storage of Large Objects ................................................................... 13
8.2
Usage of Queuing ............................................................................... 13
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8.2.1
8.2.2
8.2.3
8.2.4
8.2.5
New Media (Oracle) Database Design Template.
Object Types ............................................................................................................ 13
Queue Tables .......................................................................................................... 14
Advanced Queues ................................................................................................... 14
Consumers ............................................................................................................... 14
Producers ................................................................................................................. 14
8.3
Partitioning .......................................................................................... 14
8.4
Usage of other RDBMS Specific Features ........................................ 15
9 NON-FUNCTIONAL DESIGN...................................................................... 15
9.1
Security Design .................................................................................. 15
9.2
Availability and Resilience Design .................................................... 15
9.3
Scalability ............................................................................................ 15
9.4
Platform Management ........................................................................ 15
9.5
Performance Design ........................................................................... 15
9.6
Error Processing................................................................................. 16
9.7
Backups and Recovery policy ........................................................... 16
9.8
Archiving ............................................................................................. 16
10
ASSUMPTIONS AND ISSUES ................................................................ 16
10.1 Design Assumptions .......................................................................... 16
10.2 Outstanding Issues ............................................................................ 16
11
APPENDIX A - TABLE RELATION DIAGRAMS .................................. 17
12
APPENDIX B – MODULE LIST ............................................................... 18
13
APPENDIX C - TABLE DEFINITIONS................................................... 19
14
APPENDIX D - VIEW DEFINITIONS ...................................................... 20
15
APPENDIX E - SNAPSHOT DEFINITIONS ........................................... 21
16
APPENDIX F - TRIGGER DEFINITIONS................................................ 22
17
APPENDIX G - ENTITY TO TABLE IMPLEMENTATION ..................... 23
18
APPENDIX H - ROLE DEFINITIONS...................................................... 24
19
APPENDIX I - DATABASE DESIGN CHECKLIST ................................ 25
19.1 Checklist.............................................................................................. 25
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2 Introduction
This Database Design provides the basis for the <Subsystem/Application Name>
database design. It defines the database that will support the <Subsystem/Application
Name> Data Model. It describes both the logical and physical definition, non-functional
issues, and the database interfaces; storage aspects are defined in the physical database
design sections. The design is created with expected data volumes, functional and nonfunctional usage of the tables, and performance considerations and requirements in mind.
.
The following topics are covered in this document:
 assumptions and decisions on database design
 entity-mapping
 table, column and view definitions
 primary, unique and foreign key definitions
 column and row level validation rules (check constraints)
 rules for populating specific columns (sequences, derivations, denormalised
columns, journaling)
 interfaces and dependencies with other components
 data access description
2.1 Scope, Approach and Methods
The Database Design for the <Subsystem/Application Name> is composed of definitions
for database objects derived by mapping entities to tables, attributes to columns, unique
identifiers to unique keys and relationships to foreign keys.
During design, these initial definitions are enhanced to support the functionality
described in the functional specification / use cases and defined in the primary and
supporting modules of the application High Level Design.
2.2 How to Review
Please use the following criteria when reviewing the content of this Database Design (a
fuller checklist can be found in appendix H):
 Is the structure correct?
 Are the contents appropriate for the audience?
 Is the order logical?
 Are the contents complete?
 Is the table model complete in reflecting the logical database model?
 Is the model and module list complete in supporting the functionality described in
the functional specification / use cases ?
2.3 Related Documents
This specification refers to the following documents:
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3 Subsystem/Application Overview
Mandatory section
This section provides a brief overview of the subsystem. MUST be consistent with the
high level design (if any exists), or can refer directly to the high level design document if
this exists.
If the HLD is incorrect then this should be flagged to the Lead Designer.
Components within each area should be labelled using decimal notation. These tags must
be used in both diagrams and text when referencing subsystems and components.
3.1 Architecture
3.1.1 Hardware Architecture
This section provides an overview of the hardware architecture. Briefly identify the
hardware and present a diagram showing how the components are connected.
3.1.2 Software Architecture
This section must list the components within the subsystem/application and must include
a component diagram.
Include a diagram of all components within the subsystem/application and all external
systems. Include components, datastores and interfaces within the subsystem/application
as well as interfaces between internal components and external systems.
Label all external interfaces consistently with those used in the high level design. Label
internal interfaces for reference. If direction is indicated on an interface, make it clear
whether it denotes the direction of initiation or the main direction of dataflow.
3.1.3 Interfaces
Briefly identify the interfaces to external systems - each database interface will be
described in more detail below, and documented in an external interface specification.
3.1.4 Datastores
Briefly describe all datastores including databases, file systems and media data stores.
4 Database Design Decisions
This section contains the decisions that were made when designing the database for
<Subsystem/Application Name>. Problems, alternative solutions and motivated choices
are listed below. The section also lists any design assumptions that had to be made. In
case the assumptions are results of ambiguities or lack of details, they will need verifying
by the analyst team.
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4.1 Assumptions
List any assumptions made due to lack of information (eg. in the functional specifications
or data model).
4.2 Standards Deviations
List any deviations from the standards and guideline set out for BBC New Media
Projects. See [???] for naming standards.
4.3 Entity Mapping
This section states the mapping rules and lists tables and columns that either:
 do not originate from a single entity,
 are not implemented at all, or
 are otherwise treated in a non-trivial manner.
4.3.1 Mapping rules
When mapping entities to tables, the following rules were applied:
 Entities are mapped onto tables in a one to one manner.
 Attributes are mapped to columns in a one to one manner.
 One-to-many relationships are mapped to foreign keys.
 Many-to-many relationships are implemented using a keys-only table.
(List additional rules used).
4.3.2 Entities and Attributes Not Implemented
The following table lists entities and attributes that are not implemented as tables and
columns.
Entity/Attribute
Description
Reason for not
implementing
4.3.3 Non-trivial Mapping
The following table lists all tables that are not derived from an entity in a one-to-one
fashion. This includes arc and subtype mapping.
Table/Column
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4.3.4 Additional Objects
The following table lists database objects (tables or columns) that where not derived from
an entity, but were added to the database design for the purpose listed below. This
includes intersection tables used for mapping many-to-many relationships.
Table/column
Description
Purpose
4.3.5 Key mappings
4.3.5.1 Sequences in Keys
The following tables have primary keys created from sequences:
Table
Primary key column
Sequence
The following tables have a surrogate primary key columns instead of a composite
primary key consisting of a foreign key column plus a ‘sequence within fk’-column:
Table
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The following tables do have a composite primary key consisting of a foreign key column
plus a ‘sequence within fk’-column:
Table
(Primary) foreign key columns
Sequence
4.3.6 Other Deviations
Other deviations from a one-to-one mapping of entity and attribute names to table and
column names and any foreign key naming deviations are listed below.
Entity/Attribute/Relation
Table/Column/
Foreign Key
Column
Reason for deviating
4.4 Denormalisation
To improve performance or otherwise support specific functionality, redundancy is
sometimes added to the design. Two types of redundancy are distinguished, performance
denormalisation and functional denormalisation. The first type is aimed at improving
performance, the second is needed to support the proposed functionality of the system.
4.4.1 Performance Improvement
To maintain redundant or denormalised data needed to improve performance, the
following objects were modified:
Denormalised
Table/Column
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4.4.2 Functional Support
To maintain redundant or denormalised data needed to support the proposed functionality
of Error! Reference source not found. the following objects were modified:
Denormalised
Table/
Column
Source table or entity
Rules and methods for
maintaining integrity
4.5 Journaling and History
To accommodate for journaling of data manipulation and to keep/archive/delete historic
data, the following additions were made:
Object
Description
Journaling Issues
4.6 Business Rules
List here any rules modelled in the data model, specified for the entities in the data model
or in the functional specification that have not been implemented as table/column
constraints/column-defaults. Specify whether they are implemented as triggers or if they
will have to be implemented by the modules using the tables.
4.7 Implied Functionality
The model contains supporting modules that perform functions that may be trivial to the
users but are considered to be important functionality by the developers. Decisions
regarding database objects involved in such implied functionality are discussed below.
(Examples: Batch Handling and Printing, Authorisation, User Interface).
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Interfaces and Dependencies
5.1 Interfaces
Detailed APIs for interfaces can be described here or left to individual module interface
specifications.
5.1.1 Interface <Name/Id>
5.1.1.1 Purpose
Describe the purpose of the interface
5.1.1.2 Characteristics
Summarise the interface characteristics, consistent with the High Level Design.
5.1.1.3 Interface Architecture
Describe the interface architecture.
5.1.1.4 API and Error Conditions
Optionally describe the API and error conditions for the interface. This detail can be left
to a separate module interface specification.
5.1.1.5 Usage Examples
Optional section to describe an example of using the interface.
5.1.1.6 Security
Mandatory section to describe the protocols, user authentication, encryption, signing and
control of access (at the interface entry point). (State N/A if there is nothing to describe
here).
5.2 Dependencies
List here any dependencies for the <Subsystem / Application Name> schema. One type of
dependencies can be foreign keys across schemas. List foreign key dependencies here:
Table and column in
<subsystem /
application> schema
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Reporting and MIS
6.1 Requirements
Describe any reporting and / or MIS requirements.
6.2 Design issues
Describe the design to support reporting and / or MIS requirements.
7 Data Access
This section describes aspects on how data defined in this design is used. The section
defines which roles are needed and highlights any information that are of particular
importance for the physical database implementation (e.g. Tables subject to high insert or
delete activity, tables with certain archiving rules). (see also: Database Design
Guidelines).
7.1 Role Definitions
The following roles are defined as ‘Groups’. The definition of the roles’ privileges are
found in appendix H.
Role-name
Purpose
7.2 Users
The following users are recognised as being required.
User name
Purpose
A description should be provided as to the anticipated strategy for managing users, along
with estimates of user volumetrics
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7.3 Table Access Patterns
Below is a list of particularly performance-critical functions and their table usage. Other
volumetric information needed for the physical database design is documented in
Appendix C – Table Definitions.
Function
Peak Frequency
Tables used
Also list any tables that can be classified as one of the following:
-high-volume read only
-high-volume insert
-high-volume updates
8
Physical Implementation Considerations
8.1 Storage of Large Objects
Large objects with maximum size of 20mb will normally be stored as BLOBS, whereas
other large object will be stored as BFILE.
BLOB-columns:
<list table.column-names>
BFILE-columns:
<list DIRECTORY alias name, estimated size and which table and columns the directory
covers>
8.2 Usage of Queuing
Define and describe the use for queues(i.e. asynchronous messaging techniques) and how
they will be used. Justify why they have been used. Include a description of which
functionality the queue implements and what queuing technology is chosen to implement
it (e.g. Oracle Advanced Queue, JMS).
8.2.1 Object Types
Payload
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8.2.2 Queue Tables
Queue
Table
Payload
Sort List
Multiple
Consumers
Message
Grouping
Comment
Auto
Commit
8.2.3 Advanced Queues
Queue
Name
Table
Name
Queue
Type
Max
Retries
Retry
Delay
Retention
Time
Dependency
Tracking
Comment
8.2.4 Consumers
Queue
Name
Consumer List <list all recipients of the queue>
8.2.5 Producers
Queue
Name
Producer List < list all message originators (eg. function, trigger –
see module list Appendix)>
8.3 Partitioning
Any partitioned tables should be described as follows:
Partition
table
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Partition
value
Partition
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Partition
size
Comments (reason
for partitioning:
eg. Performance,
archiving)
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Any partitioned indexes (other than described above) should be described as follows:
Table Name
Index
Name
Partition
column
Partition
value
Partition
Name
Partition
size
Comments
(reason for
partitioning:
eg.
Performance,
archiving)
8.4 Usage of other RDBMS Specific Features
List here the use of any specific features used that are not documented in the design tool
used. A justification is needed whenever such functionality is employed.
9 Non-Functional Design
This section provides an overview of the non-functional design for the database.
9.1 Security Design
Describe how authentication, integrity and confidentiality requirements are supported
within the database and interfaces to it. This will include summarising the interface and
database security requirementr.
9.2 Availability and Resilience Design
Describe how the database design supports the subsystem / component availability and
resilience requirements.
9.3 Scalability
Identify how the database design supports scalability requirements.
9.4 Platform Management
Identify how the database design supports the monitoring and management facilities
provided by the operational Platform Management subsystem.
9.5 Performance Design
Areas of the database(/subsystem) design which need to be highly performant should be
identified in this section. Describe how the database has been designed for performance.
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9.6 Error Processing
Explain the general error processing strategy adopted by the design, and how it is
supported within the database design / to be implemented in the database code
developed.
9.7 Backups and Recovery policy
Describe the backup and recovery policy to be used.
9.8 Archiving
Describe the archiving policy to be used.
10 Assumptions and Issues
Mandatory section
10.1 Design Assumptions
Document any assumptions made during design, e.g. assumed constraints, assumptions
about other systems or where requirements analysis was unclear. See also: section 4.1
above (Database Design assumptions)
(State ‘none’ if appropriate).
10.2 Outstanding Issues
Note that at this stage, these should general have been converted either into design
statements within the main body of the document or into Design assumptions listed in
previous section.
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11 Appendix A - Table Relation Diagrams
The diagram(s) in Appendix A show the tables for the <Subsystem / Application Name>
schema and their relations. The relations are implemented as foreign key constraints.
Two separate diagrams are shown:
(i)
Logical Design
(ii)
Physical Design
Not all relations between the diagrams are shown (for clarity). This information is
available in the Table Design reports included with this document.
Legend
Drawing conventions used in the Table Relation Diagrams are defined in the design tool
used.
Describe any deviations below.
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12 Appendix B – Module List
List any modules related to (- to be implemented to support) the database design including:

modules added to effect denormalisation for performance or functional reasons

journalling or historic data maintenance

batch processing/daemons e.g. to “garbage collect” database/file systems

handling of user authentication/authorization

generic user interface handlers/controls

non-standard messaging

tool integration modules

backup and recovery

Describe any modules

All other required database functional and non-functional requirements
Module Reference
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13 Appendix C - Table Definitions
The report shows:






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Table/View Description
Column Summary
Comments
Primary, Unique and Foreign Key
(Estimated) Volumetrics (e.g. initial rows, 6 mths, 2 yr)
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14 Appendix D - View Definitions
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15 Appendix E - Snapshot Definitions
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16 Appendix F - Trigger Definitions
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17 Appendix G - Entity to Table Implementation
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18 Appendix H - Role Definitions
Detail all roles, and the privileges they will have on the schema objects (defined above).
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19 Appendix I - Database Design Checklist
This list serves as a guide for checking the quality of the Logical Database Design. By
answering the questions and taking the appropriate actions the Logical Database Design
will be completed and corrected.
19.1 Checklist

Naming Conventions
Check as prescribed by Design Standards.

Graphical Representation
Is a graphical representation available?
Is it consistent with the other documentation?
Can it be used by the build team?
In what ways does the logical model differ from the conceptual
schema?

Completeness of Specification in Design tool
Which slots in the design tool screens have been left open?
Why?

Choice of Database Objects
Have particular database objects been avoided or not used?
If so, then why? (Think of views, sequences, sequence number
tables, indexes.)

Interpretation of Conceptual Schema
Do the logical and physical models cover all and only the
conceptual schema?
Have all non trivial translations been adequately documented?
Can this interpretation easily be used in a Generator environment?

Table Definition
Check as prescribed by Design Standards.
How have super- and subtypes been handled?
Is the table usage valid with respect to the CRUD matrix. (Note
that a table may be modified through a view.)
Has the life cycle of all tables been covered completely by the
modules?

Column Definition
Check as prescribed by Design Standards.
Have domain definitions been used correctly?
Have the datatypes been defined according to the standards?
Are system generated keys used?
Is the column usage valid with respect to the CRUD matrix? (Note
that a table may be modified through a view.)
Is the life cycle covered completely by the modules?
Have datatypes been chosen adequately?
How will status columns be handled?
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Constraint Definition
Pay attention to constraints that only hold for subtypes, or that hold
under special conditions.
Check if there is no overlap between constraints.
Have all necessary constraints (PK, FK, CHECK) been defined on
views?

Definition of Relationships
Check as prescribed by Design Standards
Investigate the following:
 the design of arcs
 non transferable relationships
 recursive relationships
 time-dependencies
(Which time is used, commit time, screen time?
What operations may be performed on
time-dependent data, under what conditions?)

Definition of Other Database Objects
Have other objects (views, indexes, domains, sequences) been
defined completely and consistently?
Is there some unusual distribution or other property of the data that
makes the use of these objects (un)necessary?

Special Problems
Have special measures been taken to deal with the following:
 journaling
(What data will be journaled: user, session id,
object, operation or module, and how?
Will the journaled data be used for “rollback to X”
or “roll forward from X” purposes ?)
 high performance demands
(response time for reports, screens, overall
response time, partial)
 heavy or peak usage, high throughput
 complex mix of hardware
 robustness
 denormalisation
 non-frozen data model, out of phase development
of other systems
 long or raw columns (in a network environment)
 concurrency problems
 distributed data
 interface with external systems (database / nondatabase)
 expiration dates
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 handling of NLS support (for example multilingual, multi-currency systems, different date or
number notations)
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