Answer / siri

The Optimizer plans an execution strategy for every
SQL query submitted to it. We have also seen that the
execution strategy
for any query may be subject to change depending on various
factors. For
the Optimizer to consistently choose the optimum strategy,
it must be
provided with reliable, complete, and current demographic
information
regarding all of these factors. The best way to assure that
the Optimizer
has all the information it needs to generate optimum
execution strategies
is to COLLECT STATISTICS.

-Statistics tell the Optimizer how many rows/ value there
are.
– The Optimizer uses statistics to plan the best way to
access data.
– May improve performance of complex queries and joins.
– NUSI Bit Mapping requires collected statistics.
– Helpful in accessing a column or index with uneven value
distribution.
– Stale statistics may mislead the Optimizer into poor
decisions.
– Statistics remain valid across a reconfiguration of the
system.
– COLLECT is resource intensive and should be done during
off hours.

Answer / yuvaevergreen

-->"Collect stats" collects demographic data about the
columns or indces of a table.
-->This statistics is used by the PE to optimize the plan
which can be viewed by explain command.
-->When collect stats is executed,the statistics is stored
in data for use of PE.

Answer / tdguy

Stores the demographic data about the columns. Very
important for better performance.

What is the purpose of upsert command?

0 Answers  

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If the table does not have duplicates then which utility you can suggest to load the data ?

3 Answers  

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Suppose i have data like 2009/12/31 555555534 ' ' Generally last 2 records are wrong format it is going to error table but i don't want load error table if any wrong format in Date column Pass "NULL" how can we do it fast load

4 Answers  

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Can we Suggest as how is the process to get a job in teradata in current market??Is it easier???

1 Answers   IBM,

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6 Answers   Bank Of America, Wipro,

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What is the difference between correlated sub queries and inner queries?

4 Answers  

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Steps to create a data model?

0 Answers  

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2 Answers   IBM,

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There is a load to the Table every one hour and 24/7.Morning trafic is high, afternoon trafiic is less, Night trafiic is high.According to this situation which Utility you use and how do you load,which utility used?

4 Answers   IBM,

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what is the structure of UV table in MLOAD?

4 Answers   Cap Gemini,

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How to load specific no.of records using bteq, or fastload,or multiload

0 Answers   Infosys,

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what are the day to day activities of teradata DBA ?

0 Answers   TCS,

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