what is use of PI(primary index) AND SI(secondary index)
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Answer / gowthami
The data can be access in teradata in 3ways..
1.Full table scan
2.Primary index
3.secondary index
PRIMARY INDEX:This one is Mandatory index.Teradata
distribute data across all amps.so for distribution of data
P.I need.
accessing and retrieval is possible through primary
index.which contains..1)UNIQUE PRIMARY INDEX 3)NON UNIQUE
PRIMARY INDEX 3)PARTITIONED PRIMARY INDEX 4)NO PRIMARY
INDEX(from teradta13)
SECONDARY INDEX:only retrival possibele through secondary
index.Means it doesnot distribute the data.
Using scenario::-There is a primary index on the table.But
we are using other than primary index colums in the where
clause as part of frequently retrival data.In this situation
system does full table scan,To avoid this take SI on the table.
Friends if any one have the better ans plz add.
| Is This Answer Correct ? | 8 Yes | 0 No |
Answer / tdguy
PI - mandatory and very important in TD. Useful in
distribution and retrieval. Performance of TD highly
depends on PI.
SI - Optional and provides alternate path to data. When
choosen appropriately, this improves the performance of
queries.
| Is This Answer Correct ? | 5 Yes | 0 No |
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