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https://issues.apache.org/jira/browse/ARROW-3144?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wes McKinney updated ARROW-3144:
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Summary: [C++] Move "dictionary" member from DictionaryType to ArrayData to
allow for changing dictionaries between Array chunks (was: [C++] Implement
"variable dictionary" type to handle changing dictionaries without causing
schemas to change)
> [C++] Move "dictionary" member from DictionaryType to ArrayData to allow for
> changing dictionaries between Array chunks
> -----------------------------------------------------------------------------------------------------------------------
>
> Key: ARROW-3144
> URL: https://issues.apache.org/jira/browse/ARROW-3144
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Wes McKinney
> Assignee: Wes McKinney
> Priority: Major
> Labels: pull-request-available
> Fix For: 0.14.0
>
> Time Spent: 6h 10m
> Remaining Estimate: 0h
>
> There are a couple of inter-related issues:
> * Cases where a system might send the schema without the dictionaries, and
> the user wishes to reason about the schema and its types without knowing the
> dictionary values
> * Dictionaries that are changing, e.g. using delta dictionary messages
> {{arrow::DictionaryType}} has no "linkage" to any external object. I propose
> adding a "LinkedDictionaryType" or something similar (purely a C++
> construct), which functionally would be a subclass of {{DictionaryType}},
> which would allow a type to be created which will obtain its dictionary later
> through some kind of "Dictionary provider" interface. There is something
> similar in Java already. This would allow a dictionary to evolve via delta
> dictionaries, or for a dictionary to be retrieved later e.g. through an RPC
> or IPC layer
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