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https://issues.apache.org/jira/browse/ORC-1376?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17691368#comment-17691368
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Gang Wu commented on ORC-1376:
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[~ffacs] Thank you!
Assigned it to you. Feel free to make a PR when you are ready.
> [C++] Support schema evolution
> ------------------------------
>
> Key: ORC-1376
> URL: https://issues.apache.org/jira/browse/ORC-1376
> Project: ORC
> Issue Type: New Feature
> Components: C++
> Reporter: Gang Wu
> Assignee: Yuanping Wu
> Priority: Major
>
> The Java ORC reader supports schema evolution by comparing readSchema with
> fileSchema [1] and creates a set of ConvertTreeReaders [2] to do the
> conversion. The conversion happens when reading columnar data into vector and
> evaluating expressions for predicate push down. The C++ reader does not
> support it yet.
> The type conversion on the Java side originates from Apache Hive. We should
> define what conversions are supposed to implement on the C++ side.
> [1]
> https://github.com/apache/orc/blob/main/java/core/src/java/org/apache/orc/impl/SchemaEvolution.java
> [2]
> https://github.com/apache/orc/blob/main/java/core/src/java/org/apache/orc/impl/ConvertTreeReaderFactory.java#L60:14
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