1. Introduction to Teradata
Kanakadurga Rajanala

2. Overview What is a Independent Data Mart? What is Data Warehousing?
What is Teradata?
Teradata Architecture
Data Storage and Retrieval
Fault Tolerance
Q & A

3. Independent Data Marts
Decision
Support Information
Engg Dept
Decision
Support Information
Arts Dept
Decision
Support Information
Science Dept
How to get university wide reports?
How to prevent data redundancy?
How to maintain consistent data across departments?

4. What is a Data Warehouse?
A data warehouse is a central, enterprise wide database that contains information obtained from operational systems.
Good Data warehouse
Provides required storage capability
Performance
Scalability

5. Data Warehouse University Database Data Data Mining Warehouse Engg Dep
Science
Student/faculty info
Arts
Music
Etc…
Copied,
organized
detailed
Data
Warehouse
Data Mining

6. What is Teradata?
Teradata is an RDBMS designed for enterprise data warehousing.
Massively Parallel Processing system(MPP)
Parallelism throughout Platform
“Share Nothing” architecture
Linear Scalability

7. Teradata MPP Architecture
Physical layout of 4 node system
MPP System
Each Node is an SMP System. The maximum nodes can be up to 512.

8. BYNET Interconnect
BYNET high-speed interconnect facilitates system communication
All nodes connected via BYNET
Hardware network
Driver Software runs on each node

9. Node Architecture
Each Teradata Node is made up of hardware and software
Each node has CPUs, system disk, memory and adapters
Each node runs copy of OS and database SW
A Teradata Database node requires three distinct pieces of software:
The Teradata Database can run on the following operating systems:
UNIX MP-RAS
Microsoft Windows 2000
The Parallel Database Extensions (PDE) software layer was added to the operating system by NCR to support the parallel software environment.
A Trusted Parallel Application (TPA) uses PDE to implement virtual processors (vprocs). The Teradata Database is classified as a TPA. The four components of the Teradata Database TPA are:
AMP (Top Right)
PE (Bottom Right)
Channel Driver (Top Left)
Teradata Gateway (Bottom Left)
A Parsing Engine (PE) is a vproc that manages the dialogue between a client application and the Teradata Database, once a valid session has been established. Each PE can support a maximum of 120 sessions.
The AMP is a vproc that controls its portion of the data on the system. AMPs do the physical work associated with generating an answer set (output) including sorting, aggregating, formatting, and converting. The AMPs perform all database management functions on the required rows in the system. The AMPs work in parallel, each AMP managing the data rows stored on its single vdisk. AMPs are involved in data distribution and data access in different ways.
Channel Driver software is the means of communication between an application and the PEs assigned to channel-attached clients. There is one Channel Driver per node.
Teradata Gateway software is the means of communication between an application and the PEs assigned to network-attached clients. There is one Teradata Gateway per node.

10. V2 Virtual Processors (Vprocs)
Node Architecture
Each node has virtual processors (process)
PDE layer facilitates communication between OS and Vprocs.
Syntaxer
Optimizer
Step Gen
Dispatch
PE vproc
AMP
vproc
Vdisk
Operating System
PDE
V2 Virtual Processors (Vprocs)
Execution Engines
Run in Parallel
A Teradata Database node requires three distinct pieces of software:
The Teradata Database can run on the following operating systems:
UNIX MP-RAS
Microsoft Windows 2000
The Parallel Database Extensions (PDE) software layer was added to the operating system by NCR to support the parallel software environment.
A Trusted Parallel Application (TPA) uses PDE to implement virtual processors (vprocs). The Teradata Database is classified as a TPA. The four components of the Teradata Database TPA are:
AMP (Top Right)
PE (Bottom Right)
Channel Driver (Top Left)
Teradata Gateway (Bottom Left)
A Parsing Engine (PE) is a vproc that manages the dialogue between a client application and the Teradata Database, once a valid session has been established. Each PE can support a maximum of 120 sessions.
The AMP is a vproc that controls its portion of the data on the system. AMPs do the physical work associated with generating an answer set (output) including sorting, aggregating, formatting, and converting. The AMPs perform all database management functions on the required rows in the system. The AMPs work in parallel, each AMP managing the data rows stored on its single vdisk. AMPs are involved in data distribution and data access in different ways.
Channel Driver software is the means of communication between an application and the PEs assigned to channel-attached clients. There is one Channel Driver per node.
Teradata Gateway software is the means of communication between an application and the PEs assigned to network-attached clients. There is one Teradata Gateway per node.
No one else shares

11. Data Storage Defined by user. Used for data distribution.25 26
Pick Up Primary Index value
Array associates hash buckets to AMPs
Parsing Engine
Hashing Algorithm
Row Hash
Bucket #
Hash Map
A hashing algorithm is a standard data processing technique that takes in a data value, like last name or order number, and systematically mixes it up so that the incoming values are converted to a number in a range from zero to the specified maximum value. A successful hashing scheme scatters the input evenly over the range of possible output values.
It is predictable in that Smith will always hash to the same value and Jones will always hash to another (hopefully different) value. With a good hashing algorithm any patterns in the input data should disappear in the output data.
Teradata’s algorithm works predictably well over any data, typically loading each AMP with variations in the range of .1% to .5% between AMPs. For extremely large systems, the variation can be as low as .001% between AMPs. A Row Hash is the 32-bit result of applying a hashing algorithm to an index value. The DSW (Destination Selection Word) or Hash Bucket is represented by the high order 16 bits of the Row Hash.
Teradata also uses hashing quite differently than other data storage systems. Other hashed data storage systems equate a bucket with a physical location on disk. In Teradata, a bucket is simply an entry in a hash map. Each hash map entry points to a single AMP. Therefore, changing the number of AMPs does not require any adjustment to the hashing algorithm. Teradata simply adjusts the hash maps and redistributes any affected rows.
The hash maps must always be available to the Message Passing Layer. A Teradata Version 2 a hash map has 65,536 entries. When the hash bucket has determined the destination AMP, the full 32-bit row hash plus the Table-ID is used to assign the row to a cylinder and a data block on the AMPs disk storage. In Version 2 the algorithm can produce over 4,000,000,000 row hash values.
Hash values will be the same for non-unique primary indexes and for hash synonyms (values where different inputs produce same output), so a ‘Uniqueness value’ is added to the Row Hash. This combined value becomes the Row ID and is truly unique for every row on the database.
Message Passing Layer (BYNET)
Node-1
Node-2
AMP
AMP
AMP
AMP

12. Data Retrieval Select * from CalStateLADB.Students;
Client
Parsing Engine
Dispatcher
RET Step
RET Step
RET Step
RET Step
RET Step
Message Passing Layer
AMP
AMP
AMP
AMP 10 10 29 29 25 25 50 50 75 75

13. Teradata Scales Linearly
Scaling achieved via ‘shared nothing’ architecture and unconditional parallelism
Power is in linear scalability
where slope = 1
More nodes
More work
More users
More data
BYNET
Node1
Node2
Node3
Node4
Node
Work
Users
Data

14. Fault Tolerance BYNET Amp Amp Amp Amp Amp Amp Amp Amp CLIQUE-2
Disk Array
Disk Array
Disk Array
Disk Array

15. Summary Teradata is designed and used for enterprise data warehousing.
MPP with “Share Nothing” Architecture.
Parallelism throughout the platform.
Runs on windows and Linux.

16. References
Teradata Basics and Architecture user manual (
Teradata Software Demo CD can be ordered (free copy) from

17. Questions?