What is the default join strategy in Teradata???
Answers were Sorted based on User's Feedback
Answer / dg
The Teradata Cost based optimizer will decide the join
strategy based on the optimum path. The common startegies
followed are from Merge, Hash & Nested Join
Is This Answer Correct ? | 25 Yes | 3 No |
Answer / yuvaevergreen
Three strategies followed by optimizer are:
1.Duplication of rows of one table to every amp
--> This one is opted by optimizer when the non-PI column
is on a small table.
2.Redistribution of the non PI rows of the table to the amp
containing the matching PI row amp.
--> This one is opted when the tables are large. The non PI
column is in one table is redistributed to the amp
containing the matching PI.
3.Redistribute both the rows of the table by hash values.
--> This is chosen when the join is on a column that is not
the PI in either table. This will require the most spool
space.
Is This Answer Correct ? | 13 Yes | 3 No |
Answer / tdguy
i think there is no "default" join strategy. Optimizer
decides the type of strategy based on the best retrieval
path and other parameters to execute the query. Merge join
strategy, nested join strategy, hash join strategy and
product join strategies are the common strategies followed
by TD.
Is This Answer Correct ? | 7 Yes | 1 No |
Why do Hash joins usually perform better than Merge Joins?
In a table can we use primary key in one column and in another column both unique and not null constrains.if yes how?
What is a three-tier data warehouse?
How to copy teradata scripts from ur remote desktop to server machine?
In Teradata, what is the significance of UPSERT command?
What are the advantages of teradata?
Which Teradata concept allows more than one model generation?
If a Node is busy what are the steps you can take to avoid ?
Can you fastexport a field, which is primary key by putting equality on that key?
List the logical and conditional operators that are used with teradata along with their meanings?
Explain teradata architecture in detail with a diagram.
what is identity columns in teradata