trushev opened a new pull request, #5443:
URL: https://github.com/apache/hudi/pull/5443
## What is the purpose of the pull request
This PR adds support of reading by flink when comprehensive schema
evolution(RFC-33) enabled and there were some operations *add column*, *rename
column*, *change type of column*, *drop column*.
Supported mode: batch/cow/snapshot
## Brief change log
- Added new option to enable comprehensive schema evolution in flink
- Key changes are made inside `CopyOnWriteInputFormat`. Now, during the
opening, it calculates schema of file, if this schema differs from queried
schema, it creates cast map. After reading file, type conversion is performed
according to constructed map.
## Verify this pull request
This change added tests and can be verified as follows:
- Added unit test `TestCastMap` to verify that type conversion is correct
- Added integration test `ITTestReadWithSchemaEvo` to verify that table
with added, renamed, casted, dropped columns is read as expected. This test
uses `TestSpark3DDL` to prepare data, so it works only with `-P
scala-2.12,spark3.2`, since `TestSpark3DDL` works only with it.
## Committer checklist
- [ ] Has a corresponding JIRA in PR title & commit
- [ ] Commit message is descriptive of the change
- [ ] CI is green
- [ ] Necessary doc changes done or have another open PR
- [ ] For large changes, please consider breaking it into sub-tasks under
an umbrella JIRA.
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