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The **Primary Index **is the only thing that determines where a row will reside and the

hashing algorithm never lies. It is important that you understand this process. When a

new row arrives into Teradata, the following steps occur:

**Teradata**s PE examines the Primary Index value of the row. Teradata takes that Primary

Index value and runs it through a Hashing Algorithm. The output of the Hashing

Algorithm (i.e., a formula) is a 32-bit Row Hash.

The 32-bit Row Hash will perform two functions:

1. The 32-bit Row Hash will point to a certain spot on the Hash Map, which will

indicate which AMP will hold the row.

2. The 32-bit Row Hash will always remain with the Row as part of a Row ID.

Hashing is a mathematical process where an Index (UPI, NUPI) is converted into a 32-

bit row hash value. The key to this hashing algorithm is the Primary Index. When this

value is determined, the output of this 32-bit value is called the Row Hash.

The Hashing Algorithm will produce random, but consistent row hashes with an end

goal to produce a 32-bit**row hash**.

hashing algorithm never lies. It is important that you understand this process. When a

new row arrives into Teradata, the following steps occur:

Index value and runs it through a Hashing Algorithm. The output of the Hashing

Algorithm (i.e., a formula) is a 32-bit Row Hash.

The 32-bit Row Hash will perform two functions:

1. The 32-bit Row Hash will point to a certain spot on the Hash Map, which will

indicate which AMP will hold the row.

2. The 32-bit Row Hash will always remain with the Row as part of a Row ID.

Hashing is a mathematical process where an Index (UPI, NUPI) is converted into a 32-

bit row hash value. The key to this hashing algorithm is the Primary Index. When this

value is determined, the output of this 32-bit value is called the Row Hash.

The Hashing Algorithm will produce random, but consistent row hashes with an end

goal to produce a 32-bit

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Number of Views -1146

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Last updated

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