Teradata Interview Questions and answers
Question.1 What is the difference between FastLoad and MultiLoad?
Answer: 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.
Question.2 Which is faster?
Question.3 Difference between Inner join and outer join?
Answer: An inner join gets data from both tables where the specified data exists in both tables.
An outer join gets data from the source table at all times, and returns data from the outer joined table ONLY if it matches the criteria.[sociallocker]
Question.4 What is multi Insert?
Answer: Inserting data records into the table using multiple insert statements. Putting a semi colon in front of the key word INSERT in the next statement rather than terminating the first statement with a semi colon achieves it.
Insert into Sales “select * from customer”
Insert into Loan “select * from customer”;
Question.5 Is multi insert ANSI standard?
Question.6 How do you create a table with an existing structure of another table with data and with no data?
Answer: Create table Customer dummy as Customer with data / with no data;
Question.7 What is the opening step in Basic Teradata Query script?
Answer: Logon tdipid/username, password.
Question.8 You are calling a Bteq script, which drops a table and creates a table. It will throw an error if the table does not exist. How can you do it without throwing the error?
Answer: You can it by setting error level to zero before dropping and resetting the error level to 8 after dropping.
Question.9 ERRORLEVEL (3807)
Answer: SEVERITY 8;
Question.10 Can you FastExport a field, which is primary key by putting equality on that key?
Question.11 Did you write stored procedures in Teradata?
Answer: No, because they become a single amp operation and my company didn’t encourage that.
Question.12 What is the use of having index’s on table?
Answer: For faster record search.
Question.13 Did you use Query man or SQL assistance?
Answer: SQL assistant 6.1
Question.14. I am updating a table in Bteq. It has to update a large number of rows, so it’s really slow. What do you suggest?
Answer: In Teradata it is not recommended to update more than 1 million rows due to journal space problems, if it is less than that and it’s slow in the Bteq, you might want to add collect statistics statement before the update statement.
Question.15 Is it necessary to add? QUIT statement after a Bteq query when I am calling it in a Unix environment?
Answer: Not necessary but it is good to add a QUIT statement after a query.
Question.16 There is a column with date in it. If I want to get just month how It can be done? Can I use sub string?
Answer: Sub string is used with char fields. So it cannot be used. To extract month from a date column, ex select extract (month from ). Same thing for year or day.Or hour or minutes if it’s a time stamp (select extract (minute from column name).
Question.17 What’s the syntax of sub string?
Answer: SUBSTRING (string_expression, n1 [n2])
Question.18 Did you use CASE WHEN statement. Can you tell us a little about it?
Answer: Yes. When a case has to be selected depending upon the value of the expression.
Question.19 While creating table my DBA has FALLBACK or NO FALLBACK in his DDL. What is that?
Answer: FALLBACK requests that a second copy of each row inserted into a table be stored on another AMP in the same cluster. This is done when AMP goes down or disk fails.[/sociallocker]
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