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Thursday, 26 June 2014

COALESCE

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COALESCE is used to check if the argument is NULL, if it is NULL then it takes the default value. It will check for NOT NULL values sequent...

Identity Column in teradata

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IDENTITY column can be set on Teradata table. It can be done while creating a table and you can not alter once you created. You can not say...

Sparse join index

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SPARSE join index is being created in Teradata as a result of filtering the rows while joining with the multiple tables. They are a type of...

how To find join indexes that are defined on your table

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SELECT * FROM dbc . indices WHERE indextype = 'J' AND databasename = 'your_database_name' AND tablenam...

Query to find Skew factor of particular table

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SELECT TABLENAME , SUM ( CURRENTPERM ) /( 1024 * 1024 ) AS CURRENTPERM , ( 100 - ( AVG ( CURRENTPERM )/ MAX ( CURRENTPERM )* 100...
Monday, 10 March 2014

What are the different return codes(severity errors) in Teradata utilities?

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Ans: There are 3 basic return codes (severity errors) in teradata utilities. 0 - success 4 - Warning 8 - User error 12 - Syste...

What is explain in teradata?

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What is explain in teradata? The EXPLAIN facility is a teradata extension that provides you with an "ENGLISH" translation of...

How to make sure Optimizer chooses NUSI over Full Table Scan (FTS)?

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Answer: A optimizer would prefer FTS over NUSI, when there are no Statistics defined on NUSI columns. It would prefer scanning for ful...

When should the statistics be collected?

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Ans: Here are some excellent guidelines on when to collect statistics: ·       All Non-Unique indices ·       Non-index join colum...

How to find out list of indexes in Teradata?

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How to find out list of indexes in Teradata? IndexType Description P Nonpartitioned Primary Q Partitioned Primary S ...

How does indexing improve query performance?

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Answers: Indexing is a way to physically reorganize the records to enable some frequently used queries to run faster. The index can ...

What is the difference between MultiLoad & Fastload interns of Performance?

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Answers: If you want to load, empty table then you use the fastload, so it will very useful than the MultiLoad ,because fastload perfo...

What is a clique?

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What is a clique? A clique is a set of Teradata nodes that share a common set of disk arrays which are connected in daisy chain networ...

How Teradata makes sure that there are no duplicate rows being inserted when it’s a SET table?

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Answers: Teradata will redirect the new inserted row as per its PI to the target AMP (on the basis of its row hash value), and if it f...

How to view every column and the columns contained in indexes in Teradata?

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Answers: Following query describes each column in the Teradata RDBMS SELECT * FROM DBC.TVFields; Following query describes colum...

How to select first N Records in Teradata?

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Answers: To select N records in Teradata you can use RANK function. Query syntax would be as follows SELECT BOOK_NAME, BOOK_COUNT,...

Where does TD store transient journal?

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Ans: In perm space -> dbc.transientjournal But that special table can grow over dbc's perm limit until the whole system runs o...

What are the advantages and dis-advantages of secondary Indexes?

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Answer: Advantages: 1. A secondary index might be created and dropped dynamically 2.A table may have up to 32 secondary indexes. ...

What are the difference types of temporary tables in Teradata?

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Answers: a.         Global temporary tables b.         Volatile temporary tables c.         Derived tables Global Temporary ta...

How do you find out number of AMP's in the Given system

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Answer 1.running following query in queryman Select HASHAMP () +1; 2. We can find out complete configuration details of nodes an...