CSUM and ROWNUMBER comparison in Teradata - Example script with statistics and syntax - Surrogate key generation in Teradata We keep getting questions about which one to use for sequence number generation in Teradata. Many people use CSUM(1,1) as its easier and other databases support that. But, in Teradata. ➠ How to generate surrogate key in Teradata By using analytical functions By using CSUM analytical function, Syntax/Example 1: SELECT (SELECT ZEROIFNULL(MAX(empno)) FROM employee) + CSUM(1,1) AS surrogatekey1newempno,empno,empname from employee; Single AMP (usually vproc 0). ➠ How to generate surrogate key in Teradata By using analytical functions By using CSUM analytical function, Syntax/Example 1: SELECT (SELECT ZEROIFNULL(MAX(empno)) FROM employee) + CSUM(1,1) AS surrogatekey1newempno,empno,empname from.

1. Generate Surrogate Key In Teradata Update
2. Generating Surrogate Key In Teradata
3. Generate Surrogate Key In Teradata Office
4. Generate Surrogate Key In Teradata Data

Generate Surrogate Key In Teradata Update

Teradata: Surrogate Key Concept

https://listingburn.weebly.com/home/download-vba-for-mac-excel. Surrogate Key is a unique, database supplied or generated identifier generally used as the primary key/index of a table.

Jul 30, 2014  Surrogate keys are auto incremented numbers that have no real world meaning. Auto incremented means that each row will have the next highest number. Natural keys are keys created from the columns. Dec 30, 2019  Teradata Identity Columns: You often need a counter that is automatically generated and is unique. Identity columns are ideal for this. Apr 20, 2006  The first problem is inherently caused by inserting meaningless data, and is always a problem, even with the built-in surrogate keys where the RDBMS provides a mechanism to retrieve the value. Sequences: a better surrogate key. Surrogate keys. As previously defined (see “Surrogate key” under “Definitions” on page 78), a surrogate key is an artificial, simple key used to identify individual entities when there is no natural key or when the situation demands a simple key, but no natural simple key exists. Surrogate keys do not identify individual entities in a meaningful way: they are simply an arbitrary method to distinguish among those entities (see Hall.

➠ When to use a surrogate key

• Surrogate key should be used if each row of table cannot be uniquely identified using 1 or more columns.
• Surrogate key can also be used when a unique key is too long and non-numeric.

Generating Surrogate Key In Teradata

➠ Advantages of surrogate key

• Each row can be uniquely identified within a table using surrogate key value.
• Surrogate key can be used as primary index for a table to distribute data evenly on all the AMPs.

➠ Disadvantages of surrogate key

• We cannot derive any meaning or relationship between the surrogate key and the rest of the data columns in a row, therefore surrogate keys have no meaning to the users.
• There will be cases when data will be shared among different databases. In this case, same rows(from different database) may have different surrogate key and different rows(from different database) may have same surrogate key.

Generate Surrogate Key In Teradata Office

➠ How to generate surrogate key in Teradata

• By using analytical functions
  1. By using CSUM analytical function, Syntax/Example 1:Single AMP (usually vproc 0) generally processes all the data when using CSUM(1,1)
     
  2. By using SUM analytical function, Syntax/Example 2:
     
  3. By using ROW_NUMBER analytical function, Syntax/Example 3:Note: '(SELECT ZEROIFNULL(MAX(emp_no)) FROM employee)' is used in above examples to generate new sequence which must be greater than the current max value present in the table.
  
  
• By using Identity column, check Identity Columns page for more detail on Identity Column(Sequence) in Teradata.
  Syntax/Example 4:Note: There will always be gaps in generated number when using identity column because in Teradata it is not one sequence but multiple parallel sequences(one on each AMP).

Generate Surrogate Key In Teradata Data