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Introduction to the Teradata® RDBMS for UNIX® Version 2 Release 2.1 - NCR

NCR Introduction to the Teradata® RDBMS for UNIX® Version 2 Release 2.1 - NCR, 1998. - 315 p.
Download (direct link): inntroduktionteradata1998.pdf
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• Fault tolerance to ensure data integrity

• Network connectivity

• Manageable growth

• Relational database management system

• Faster than other relational systems

• Common access language

• Single data store for multiple clients in a client/server architecture

The hardware component of the first generation Teradata RDBMS was a database machine. The current generation machine is a general purpose massively parallel machine running the Teradata RDBMS as a trusted parallel application (TPA). The earliest database machines were comprised of specialized hardware components. These machines were very expensive to implement and did not provide improved performance.

The concept behind the Teradata RDBMS was to build an inexpensive system using mostly off-the-shelf hardware components that would meet and exceed the performance of conventional database management systems using relational database management.

The architecture incorporates a parallel, distributed architecture in which the distributed functions communicate by means of a fast interconnect structure. This proprietary interconnect structure in the current architecture is known as the BYNET (for MPP systems) or the Vnet (for SMP systems).

One of the principal goals for the design of the Teradata RDBMS was to provide a single data store for any number of client architectures. This Shared Information Architecture (SIA) eliminates the need for maintaining duplicate databases on multiple platforms. With the SIA, most mainframe clients, workstations, and personal


Introduction to the Teradata RDBMS for UNIX

Design Perspectives

computers can access and manipulate the same database simultaneously.

The following figure illustrates the principle of the SIA.

Figure 1-1 Teradata RDBMS Shared Information Architecture


Introduction to the Teradata RDBMS for UNIX


Teradata Database Software


Structured Query Language (SQL)

Teradata Database Software

The Teradata Database Software is the foundation for the relational database server. Its purpose is to support SQL manipulations of the database.

The server software includes the following components:

• Channel communications support

• LAN gateway communications support

• SQL parser

• Request dispatcher

• Session control

• Database manager

• File manager

The structured query language (SQL) is a data sublanguage designed specifically for manipulating data in relational databases. SQL is the only language the Teradata RDBMS understands, so all database manipulations, whether embedded in an application program or resulting from an interactive query, use SQL and SQL only.

The figure shows a process flow of a SQL statement through the Teradata RDBMS on a channel-attached system.

Process flow in a network-attached system is somewhat different (substituting the micro operating system (MOSI) and micro Teradata Director Program (MTDP) for the TDP), but the basic idea is very similar.


Introduction to the Teradata RDBMS for UNIX

Teradata Database Software

Figure 1-2 Process Flow of a SQL Statement Through the Teradata RDBMS

Introduction to the Teradata RDBMS for UNIX


Teradata Database Software

The following table describes the process flows illustrated by this picture.

Stage Process
1 A user generates an SQL query on the channel-attached client. The query can either be from a BTEQ session at an interactive terminal, from a compatible fourth generation language, or can originate from within an application program coded in a host language.
2 The request/results packaging component, CLI, packages the request and sends it to the TDP for routing to the server.
3 The TDP establishes a session, then routes the request across the communications channel to the parsing engine (PE).
4 The parser component of the PE opens the request package and parses the SQL code for processing, interprets it, checks its syntax, evaluates its semantics, and optimizes the access plan.
IF the SQL source code parses . . . THEN the . . .
without errors the parser decodes the request into a series of work steps and passes them to the dispatcher.
with errors the dispatcher receives the appropriate error message and returns it to the requester. Processing terminates.
The dispatcher sequences the steps and passes them on to the BYNET (or Vnet) with instructions about whether the steps are for one Access Module Process (AMP), an AMP group, or for all AMPs.
5 The BYNET (or Vnet on a single node system) distributes the execution steps to the appropriate AMP for processing.
6 The AMPs process the execution steps by performing select, insert, delete, and update operations on the database. The AMPs make these operations by making calls to the file system. The AMPs also perform other functions such as journaling, space accounting, and index maintenance.
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