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What is the use of Hash tables in DI Studio

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Contributor SYN
Contributor
Posts: 39

What is the use of Hash tables in DI Studio

What is the use of Hash tables in DI Studio? Can any body explain with example. Thank you.

SAS Employee RMP
SAS Employee
Posts: 52

Re: What is the use of Hash tables in DI Studio

Hash tables are used in the Lookup transformation where lookups are performed against data in memory. This can have a significant impact on performance. Maybe you could be more specific with your question.

Super Contributor
Posts: 349

Re: What is the use of Hash tables in DI Studio

Hi,

See the definition from SAS DI documentation.

The optimizer considers a hash join when an index join is eliminated as a possibility. With

a hash join, the smaller table is reconfigured in memory as a hash table. SQL sequentially

scans the larger table and performs row-by-row hash lookup against the small table to form

the result set. A memory-sizing formula, which is not presented here, determines whether

a hash join is chosen.

Thanks,

Shiva

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