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https://issues.apache.org/jira/browse/ARROW-8464?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrew Lamb updated ARROW-8464:
-------------------------------
    Description: 
Usecases: Efficiently process large columns of low cardinality Strings
 
 * BatchIterator should accept both DictionaryBatch and RecordBatch
 * Type Coercion optimizer rule should inject expression for converting 
dictionary value types to index types (for equality expressions, and IN(values, 
...)
 * Physical expression would lookup index for dictionary values referenced in 
the query so that at runtime, only indices are being compared per batch

  was:
 
 * BatchIterator should accept both DictionaryBatch and RecordBatch
 * Type Coercion optimizer rule should inject expression for converting 
dictionary value types to index types (for equality expressions, and IN(values, 
...)
 * Physical expression would lookup index for dictionary values referenced in 
the query so that at runtime, only indices are being compared per batch


> [Rust] [DataFusion] Add support for dictionary types
> ----------------------------------------------------
>
>                 Key: ARROW-8464
>                 URL: https://issues.apache.org/jira/browse/ARROW-8464
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: Rust - DataFusion
>            Reporter: Andy Grove
>            Priority: Major
>
> Usecases: Efficiently process large columns of low cardinality Strings
>  
>  * BatchIterator should accept both DictionaryBatch and RecordBatch
>  * Type Coercion optimizer rule should inject expression for converting 
> dictionary value types to index types (for equality expressions, and 
> IN(values, ...)
>  * Physical expression would lookup index for dictionary values referenced in 
> the query so that at runtime, only indices are being compared per batch



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