Hash Maps



DSW(distribution selection word)





These core tutorials will help you to learn the Hash Maps in TeraData. For an in-depth

understanding and practical experience, explore Teradata Training and Certification.

Hash Map provides relationship between row hash value[DSW] and Amp address

Primary index Physical Mechanism [Storage & retrieval Party id mechanism]





The  dates distribution in the Amp’s and amp contains the data in rowed logical Sequence


Inside the Amp

Sel * From party where Pid=2




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Hash synonym(or) Hash collisions

Getting same row hash values for the same (or) to PI value is called hash synonym(or) Hash collision

In this situation to identify every row system takes a concept called rowed

It is useful to identify every record unique in the am

It is taken by the amp only

It contain 64 bits first 32 bits are row hash value, next 32 bits are u values



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