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Wes McKinney commented on ARROW-3144: ------------------------------------- See related discussion in patch for ARROW-554 https://github.com/apache/arrow/pull/3165#discussion_r243021715 > [C++] Better solution for cases where dictionaries are unknown at schema > reconstruction time, or for delta dictionaries > ----------------------------------------------------------------------------------------------------------------------- > > Key: ARROW-3144 > URL: https://issues.apache.org/jira/browse/ARROW-3144 > Project: Apache Arrow > Issue Type: Improvement > Components: C++ > Reporter: Wes McKinney > Priority: Major > Fix For: 0.13.0 > > > 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)