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https://issues.apache.org/jira/browse/ARROW-462?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wes McKinney updated ARROW-462:
-------------------------------
Description:
We use a hash table to extract unique values and dictionary indices. There may
be an opportunity to consolidate common code from the dictionary encoding
implementation implemented in parquet-cpp (but the dictionary indices will not
be run-length encoded in Arrow):
https://github.com/apache/parquet-cpp/blob/master/src/parquet/encodings/dictionary-encoding.h
This functionality also needs to permit encoding split across multiple record
batches -- so the hash table would be a stateful entity, and we can continue to
hash more chunks of data to dictionary-encode multiple arrays with a shared
dictionary at the end.
was:
We use a hash table to extract unique values and dictionary indices. There may
be an opportunity to consolidate common code from the dictionary encoding
implementation implemented in parquet-cpp (but the dictionary indices will not
be run-length encoded in Arrow):
https://github.com/apache/parquet-cpp/blob/master/src/parquet/encodings/dictionary-encoding.h
> [C++] Implement in-memory conversions between non-nested primitive types and
> DictionaryArray equivalent
> -------------------------------------------------------------------------------------------------------
>
> Key: ARROW-462
> URL: https://issues.apache.org/jira/browse/ARROW-462
> Project: Apache Arrow
> Issue Type: New Feature
> Components: C++
> Reporter: Wes McKinney
>
> We use a hash table to extract unique values and dictionary indices. There
> may be an opportunity to consolidate common code from the dictionary encoding
> implementation implemented in parquet-cpp (but the dictionary indices will
> not be run-length encoded in Arrow):
> https://github.com/apache/parquet-cpp/blob/master/src/parquet/encodings/dictionary-encoding.h
> This functionality also needs to permit encoding split across multiple record
> batches -- so the hash table would be a stateful entity, and we can continue
> to hash more chunks of data to dictionary-encode multiple arrays with a
> shared dictionary at the end.
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