A clique is a set of Teradata nodes that share a common set of disk arrays which are connected in daisy chain network to each disk array controller. Clique is mainly used to prevent node failures.

Skewness in Teradata. Skewness is the statistical term, which refers to the row distribution on AMPs. If the data is highly skewed, it means some AMPs are having more rows and some very less

Transaction mode is an area where the perspective of the Teradata RDMBS and ANSI experience a departure. Teradata, by default, is completely non-case specific. ANSI requires just the opposite condition, everything is case specific and as we saw earlier, dictates that table and column names be in capital letters.

This is probably a little restrictive and I tend to agree completely with the Teradata implementation. At the same time, Teradata allows the user to work in either mode within a session when connected to the RDBMS. The choice is up to the user when BTEQ is the client interface software.

For instance, within BTEQ either of the following commands can be used before logging onto the database:

.SET SESSION TRANSACTION ANSI
Or
.SET SESSION TRANSACTION BTET

The BTET transaction is simply an acronym made from a consolidation of the BEGIN TRANSACTION (BT) and END TRANSACTION (ET) commands to represent Teradata mode.

Performance Monitor (PMON) and its Chracterstics

• An orderly presentation of performance, usage, status, contention, and availability data for Teradata Database at the overall, resource, and session levels
• It can be started via TD Manager or as Standalone Application.

• PMON collects near

o   Real-Time System Configuration, Resource Usage,o   Session Information from the Teradata Database either directly from TD DB through Teradata Manager or PC Workstation

• PMON formats and displays this Information and Performance as requested on Four  Set of Screens

o   General Health Information (Configuration and Summary )§  Refreshed Automatically at a User Defined Level§  Configuration and Performance Summaryo   Resource Usage Information (Nodes and Vprocs) (Both Physical and Virtual))§  Data is Collected and Displayed when Requested by User.§  Graphs show a user Selected Data Point for each Node (Vproc).
 o   Session and Workload Information§  Data is Collected and Displayed when Requested by User.§  The Session Summary screen shows all the sessions currently logged onto the system and allows the user to filter these sessions and to sort them in various ways§  It also show which Session are Currently Blocked.§  It allows to examine the Active Workload and Queries.

• Historical Session Information (Session history) 
  •  A list of Historical Session file is displayed. User can analyze from this list and that data displayed on Regular Session Information Screens
• PMON allows to Abort Sessions that are causing system problems.

Provides below functional areas for Monitoring System activity as well:

• Control functions
• Graphic displays of Resource and Session Data

Give a justifiable reason why Multi-load supports NUSI instead of USI.

The index sub-table row happens to be on the same Amp in the same way as the data row in NUSI. Thus, each Amp is operated separately and in a parallel manner.

Difference between MultiLoad and TPump?

Answer:

Tpump provides an alternative to MultiLoad for low volume batch maintenance of large databases under control of a Teradata system. Tpump updates information in real time, acquiring every bit of a data from the client system with low processor utilization. It does this through a continuous feed of data into the data warehouse, rather than the traditional batch updates. Continuous updates results in more accurate, timely data. Tpump uses row hash locks than table level locks. This allows you to run queries while Tpump is running.

Give a justifiable reason why Multi-load supports NUSI instead of USI.

The index sub-table row happens to be on the same Amp in the same way as the data row in NUSI. Thus, each Amp is operated separately and in a parallel manner.

Explain the meaning of Amp?

Amp basically stands for Access Module Processor and happens to be a processor working virtually and is basically used for managing a single portion of the database. This particular portion of database cannot be shared by any other Amp. Thus, this form of architecture is commonly referred to as shared-nothing architecture.

Amp basically consists of a Database Manager Subsystem and is capable of performing the operations mentioned below.

– Performing DML

– Performing DDL

– Implementing Aggregations and Joins.

– Releasing and applying locks, etc.

What is meant by a Parsing Engine?

PE happens to be a kind Vproc. Its primary function is to take SQL requests and deliver responses in SQL. It consists of a wide array of software components that are used to break SQL into various steps and then send those steps to AMPs

What are the functions of a Parser?

A Parser: –

– Checks semantics errors

– Checks syntactical errors

– Checks object existence

How many sessions of MAX is PE capable of handling at a particular time?

PE can handle a total of 120 sessions at a particular point of time.

Explain BYNET.

BYNET basically serves as a medium of communication between the components. It is primarily responsible for sending messages and also responsible for performing merging, as well as sorting operations.

In Teradata, what is the significance of UPSERT command?

UPSERT basically stands for Update Else Insert. This option is available only in Teradata.