[jira] [Updated] (ARROW-3144) [C++] Move "dictionary" member from DictionaryType to ArrayData to allow for changing dictionaries between Array chunks

["Wes McKinney (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-3144?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Wes McKinney updated ARROW-3144:
--------------------------------
    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



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)