Teradata Basics

Table of Contents

Major Components of Teradata:

How Teradata database store the data

The Parsing Engine dispatches request to insert a row.
The Message Passing Layer ensures that a row gets to the appropriate AMP (Access Module Processor).
AMP stores the row on its associated (logical) disk.
An AMP manages a logical or virtual disk which is mapped to multiple physical.

How Teradata database retrieval the data (Rows retrieval from Table)

The Parsing Engine dispatches a request to retrieve one or more rows.
The Message Passing Layer ensures that the appropriate AMP(s) are activated.
The AMP(s)locate and retrieve desired row(s) in parallel access.
Message Passing Layer returns the retrieved rows to PE. The PE returns row(s) to requesting client application

Below are the list of objects contains in Teradata database or User:

Tables–rows and columns of data
Views–predefined subsets of existing tables
Macros–predefined, stored SQL statements
Triggers–SQL statements associated with a table
Stored Procedures–program stored within Teradata
User-Defined Function–function (C program) to provide additional SQL functionality
Join and Hash Indexes –separate index structures stored as objects within a database
Permanent Journals–table used to store before and/or after images for recovery

Objects which require permanent spaces are:- Tables , Triggers, Stored Procedures, User-Defined Function, Join and Hash Indexes & Permanent Journals
Objects which not require permanent spaces are:- Macros & Views

Join and Hash Indexes and Permanent Journals – These aren’t directly accessed by users (these will be explained in details in another blog)
These objects are created, maintained, and deleted using SQL.
Object definitions are stored in the DD/D.