Answer / tdguy

When an USI is created, a subtable is generated and stored.
When that USI is used in the query,TD recognizes the USI.
TD will hash the SI and the hash map will point to the
subtable in one AMP. The subtable row will point the row-id
and the row is fetched from the second amp.

Answer / nitin bansal

Generally the Parsing Engine preapres a two amp plan for
USI, as in case of USI there will be a subtable which has
the hashed value of the USI and the ROW ID of the Primary
Index. So when you search using the USI first it will go to
the AMP which has the subtable and then using the ROW id
from the subtable it will go to the AMP where the actual
row resides.

In a case where the PI and USI value are same it can be a
one amp operation as the HASHED value of oth the PI and USI
will go to the same AMP.

Answer / gowthami

Thanks alot nitin for ur rly.

i would like share 1 interview question which was asked in
ibm.

Q)there are two rows like aa6588fhfhf,gru282vbvv.
Question is howcan we retrive the first number from two
rows.

thanks in advance

If the PMON is not working then how do you identify and monitor all the processes, resources and sessions ?

0 Answers  

---

Hash collision?

3 Answers   Satyam,

---

How to run the Teradata jobs in unix environment ???

4 Answers   IBM,

---

What are the types of tables in Teradata

22 Answers   Cap Gemini, Cognizant, Infosys,

---

What is the multi-insert?

0 Answers  

---

---

how can we analyze the locks ?

0 Answers   HP,

---

If the script is aborted. why it is aborted and how can you identify ?

1 Answers  

---

Highlight a few of the advantages that ETL tools have over Teradata.

0 Answers  

---

What are the string manipulation operators and functions associated with teradata?

0 Answers  

---

List out all forms of LOCKS that are available in Teradata.

0 Answers  

---

What is multi insert?

0 Answers  

---

Where we use PPI in real time??? What is the disadvantages of PPI?

3 Answers   IBM, Mphasis,

---