what is identity column in TD?
Answers were Sorted based on User's Feedback
Answer / surendra reddy duggireddy
Identity Columns generate a system-generated number for
every row as it is inserted
in the table. It is also knows as a DBS Generated Unique
Primary Index. Identity
Columns are used if you want to guarantee row uniqueness in
a table and they can
simplify the initial port from databases other than
Teradata. They are often used as the
Primary Index so they can guarantee even distribution. In
some cases they are utilized to
optimize and simplify the first port from another database
that uses generated keys.
Identity columns do NOT need to be part of the Primary
Index, but they are often used
for that purpose because they provide even data
distribution. The biggest rule is that
you can only specify one Identity Column per table
Example:
-------
Create Table Employee_Table
( Employee_No INTEGER
GENERATED ALWAYS AS IDENTITY
(START WITH 1 INCREMENT BY 5
MAXVALUE 1000000
NO CYCLE)
, Dept_No INTEGER
,First_Name CHAR(20)
,Last_Name CHAR(20)
,Salary DECIMAL (10,2)
) PRIMARY INDEX (Employee_No);
Is This Answer Correct ? | 8 Yes | 0 No |
Answer / yuvaevergreen
Identity columns are system generated values. Generally
these columns are used for unique values. Some restrictions are
1. Only 1 column can be specified as identity column.
2. PPIs, Join indexes, hash indexes cannot have identity
columns as indexes.
3."Default" and "Always with cycle" option in identity
columns may result in duplicates.
Is This Answer Correct ? | 3 Yes | 0 No |
What does sleep function does in fast load?
Highlight the limitations of TPUMP Utility.
What is teradata?
IN A TABLE CAN WE USE PRIMARY KEY IN ONE COLUMN AND IN ANOTHER COLUMN BOTH UNIQUE AND NOT NULL CONSTRAINS.IF YES HOW?PLZ GIVE ME A EXAMPLE.
How many types of index are present in teradata?
write a query following data. 123.45 is input.write a query after decimal (ex:.45) load into database ?how it possible?
what are the default access rights in the teradata?
How do you eliminate duplicates?
What does Amp contain and what are all the operations that it performs?
what is identity columns in TD?
My table got locked during mload due to a failed job. What do I do to perform other operations on it?
What is teradata? What are some primary characteristics of teradata?