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61.What is node? How many nodes and AMPs used in your previous project?

Node is a database running in a server. We used 318 nodes and each node has 2 to 4 AMPS.

62.What is a clique?

Clique is a group of disk arrays physically cabled to a group of nodes.

63.Interviewer explained about their project (Environment, nature of work)?

Listen to them carefully so that at the end of the interview you can ask questions about the project when you are given a chance to ask questions. of the project.

64.What is the difference between FastLoad and MultiLoad?

FastLoad uses multiple sessions to quickly load large amount of data on empty table. MultiLoad is used for high-volume maintenance on tables and views. It works with non-empty tables also. Maximum 5 tables can be used in MultiLoad.

65.Have you used procedures?

No. I have not used procedures. But I have expertise knowledge writing procedures. My company have not encouraged me to write procedures because it becomes single AMP operation, as such uses lot of resources and expensive in terms of resource and time.

66.What is the purpose of indexes?

An index is a mechanism that can be used by the SQL query optimizer to make table access more performant. Indexes enhance data access by providing a more-or-less direct path to stored data and avoiding the necessity to perform full table scans to locate the small number of rows you typically want to retrieve or update.

67.What is primary index and secondary index?

Primary index is the mechanism for assigning a data row to an AMP and a location on the AMP’s disks. Indexes also used to access rows from a table without having to search the entire table.
Secondary indexes enhance set selection by specifying access paths less frequently used than the primary index path. Secondary indexes are also used to facilitate aggregate operations. If a secondary index covers a query, then the Optimizer determines that it would be less costly to accesses its rows directly rather than using it to access the base table rows it points to. Sometimes multiple secondary indexes with low individual selectivity can be overlapped and bit mapped to provide enhanced

68.What are the things to considered while creating secondary index?

Creating a secondary index causes Teradata to build a sub-table to contain its index rows, thus adding another set of rows that requires updating each time a table row is inserted, deleted, or updated. Secondary index sub-tables are also duplicated whenever a table is defined with FALLBACK, so the maintenance overhead is effectively doubled.[/sociallocker]

69.Explain Teradata Architecture ?

Teradata Architecture majorly consists of Parsing Engine (PE) , BYNET, Access Module Processors (AMP) and VDISK.

70.What is Primary Index in Teradata and how it is different from Primary Key ?

Primary Index is used for determining the access path to retrieve or store data into any table in Teradata

71.How Teradata distributes rows in AMP’s ?

Teradata uses ROWHASH on PRIMARY INDEX column to determine which AMP should store the data

72.How to determine the size of table in Teradata?

In Teradata, we can use DBC.TABLESIZE view to check the storage space used by any Table

73.How to check SQL history in Teradata?

In Teradata we can use DBC.QRYLOG to check SQL history








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