What is Join Index in TD and How it works?
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Answer / veni botcha
JOIN INDEX:
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Join Index is nothing but pre-joining 2 or more tables or
views which are commonly joined in order to reduce the
joining overhead.
So teradata uses the join index instead of resolving the
joins in the participating base tables.
They increase the efficiency and performance of join queries.
They can have different primary indexes than the base tables
and also are automatically updated as and when the base rows
are updated. they can have repeating values.
There are 3 types of join indexes:
1)Single table join index - here the rows are distributed
based on the foreign key hash value of the base table.
2) Multi table join index - joining two tables.
3) Aggregate join index - performing the aggregates but only
sum and count.
| Is This Answer Correct ? | 43 Yes | 9 No |
Answer / yuvaevergreen
Join index stores the joined rows to two or more tables in
the permanent space. Not beneficiary always. Space
consumptions may be a problem. Can be used whenever large
tables are consistently and frequently joined and space may
not be a problem.
| Is This Answer Correct ? | 10 Yes | 2 No |
Answer / tdguy
In this join index table, rows from two or more tables are
joined and stored in perm space. This table is updated
whenever the underlying rows are modified in the base
tables. These indexes can be very much useful for the
frequent queries. Advantage is faster processing.
Disadvantage is use of space and whenever join involves
atleast one column out of this join index, then this index
table would be of no use. Entire join would have to be done
separately.
| Is This Answer Correct ? | 6 Yes | 0 No |
Answer / kiran
It is an indexing structure containing columns from one or
more base tables.
supose one query frequently request a perticular join on
multiple tables that is recomdable.
| Is This Answer Correct ? | 4 Yes | 1 No |
Answer / rashid equbal
Join Index is nothing but pre-joning 2 or more tables or
views which are commonly joined in order to reduce the
joining overhead.
So teradata usdes the join index instead of resolving the
joins in the participating base tables.
They increase the efficiency and performance of join
queries.
They can have different primary indexes than the base tables
and also are automatically updated as and when the base rows
are updated. they can have repeating values.
There are 3 types of join indexes:
1) Single table join index - here the rows are distributed
based on the foreign key hash value of the base table.
2) Multi table join index - joining two tables.
3) Aggregate join index - performing the aggregates but
only sum and count.
| Is This Answer Correct ? | 7 Yes | 5 No |
Answer / ponga da ponga
mate.. u r copy pasting the same thing again and
again,,,,,booooo
| Is This Answer Correct ? | 2 Yes | 3 No |
sel a.t1,b.t1 from emp a left outer join dept b ON a.id=b.id where b.deptno=10; sel a.t1,b.t1 from emp a left outer join dept b ON a.id=b.id and b.deptno=10; what is the difference on the above 2 queries?
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