Teradata Basics

Major Components of Teradata:

• Parsing Engine
• The Message Passing Layer (MPL)
• Access Module Processor (AMP)
• Virtual Disk

Parsing Engines (PE)

• Manage sessions for users
• Parse, optimize, and send your request to the AMPs as execution steps
• Returns answer set response back to clientMessage Passing Layer (MPL)
• Allows PEs and AMPs to communicate with each other

Access Module Processors (AMP)

• Owns and manages its storage
• Performs the steps sent by the PEs

Virtual Disks (Vdisk)

• Space owned by the AMP and is used to hold user data (rows within tables).
• Maps to physical space in a disk array.

Teradata Storage Architecture

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.

Teradata Retrieval Architecture

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

Teradata Objects

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

Important Note:

• 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.

Jami Raj

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