[arrow-ipc]: dictionary builders for delta - doc fix and integration tests for nested types#9853
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alamb merged 5 commits intoMay 3, 2026
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albertlockett
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@JakeDern would you mind having a look at this? |
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Looks good to me, thanks for adding the tests! |
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FYI @adamreichold |
alamb
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Looks good to me -- thank you @albertlockett and @JakeDern
| RecordBatch::try_new(schema.clone(), vec![Arc::new(array) as ArrayRef]).unwrap() | ||
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| /// build batches where the dictionary array is nested within a struct array |
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is it worth also mentioning that the dict array is the first array?
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Thanks @albertlockett |
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…tests for nested types (apache#9853) # Which issue does this PR close? <!-- We generally require a GitHub issue to be filed for all bug fixes and enhancements and this helps us generate change logs for our releases. You can link an issue to this PR using the GitHub syntax. --> - Closes #NNN. # Rationale for this change <!-- Why are you proposing this change? If this is already explained clearly in the issue then this section is not needed. Explaining clearly why changes are proposed helps reviewers understand your changes and offer better suggestions for fixes. --> In apache#9600 we added capability to call `finish_preserve_values` on any array builder, and it will propagate the choice to preserve dictionary values down into the nested builders. I thought it would be good to extend the integration tests we have in https://github.com/apache/arrow-rs/blob/main/arrow-ipc/tests/test_delta_dictionary.rs to cover the use cases, which was to call the method on builders with nested child builders (such as `StructBuilder` and `ListBuilder`). While reviewing the PR for apache#9600 I also noticed a small issue with the docs related to using the StreamWriter with delta dictionaries, notably that we set up some options to use delta dictionaries but don't pass the options into the `StreamWriter` constructor: https://docs.rs/arrow-ipc/58.1.0/arrow_ipc/writer/struct.StreamWriter.html#example---efficient-delta-dictionaries # What changes are included in this PR? <!-- There is no need to duplicate the description in the issue here but it is sometimes worth providing a summary of the individual changes in this PR. --> - adds cases to the integration tests for delta dictionaries covering `ListBuilder` and `StructBuilder` - small docs correction for `StreamWriter` # Are these changes tested? <!-- We typically require tests for all PRs in order to: 1. Prevent the code from being accidentally broken by subsequent changes 2. Serve as another way to document the expected behavior of the code If tests are not included in your PR, please explain why (for example, are they covered by existing tests)? --> it is simply docs & tests # Are there any user-facing changes? No <!-- If there are user-facing changes then we may require documentation to be updated before approving the PR. If there are any breaking changes to public APIs, please call them out. -->
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Which issue does this PR close?
Rationale for this change
In #9600 we added capability to call
finish_preserve_valueson any array builder, and it will propagate the choice to preserve dictionary values down into the nested builders. I thought it would be good to extend the integration tests we have in https://github.com/apache/arrow-rs/blob/main/arrow-ipc/tests/test_delta_dictionary.rs to cover the use cases, which was to call the method on builders with nested child builders (such asStructBuilderandListBuilder).While reviewing the PR for #9600 I also noticed a small issue with the docs related to using the StreamWriter with delta dictionaries, notably that we set up some options to use delta dictionaries but don't pass the options into the
StreamWriterconstructor:https://docs.rs/arrow-ipc/58.1.0/arrow_ipc/writer/struct.StreamWriter.html#example---efficient-delta-dictionaries
What changes are included in this PR?
ListBuilderandStructBuilderStreamWriterAre these changes tested?
it is simply docs & tests
Are there any user-facing changes?
No