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https://issues.apache.org/jira/browse/ARROW-12411?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated ARROW-12411:
-----------------------------------
Labels: pull-request-available (was: )
> [Rust] Add Builder interface for adding Arrays to record batches
> ----------------------------------------------------------------
>
> Key: ARROW-12411
> URL: https://issues.apache.org/jira/browse/ARROW-12411
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Rust
> Reporter: Andrew Lamb
> Assignee: Andrew Lamb
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Use case:
> While writing tests (both in IOx and in DataFusion) where I need a single
> `RecordBatch`, I often find myself doing something like this:
> ```
> let schema = Arc::new(Schema::new(vec![
> ArrowField::new("float_field", ArrowDataType::Float64, true),
> ArrowField::new("time", ArrowDataType::Int64, true),
> ]));
> let float_array: ArrayRef = Arc::new(Float64Array::from(vec![10.1,
> 20.1, 30.1, 40.1]));
> let timestamp_array: ArrayRef = Arc::new(Int64Array::from(vec![1000,
> 2000, 3000, 4000]));
> let batch = RecordBatch::try_new(schema, vec![float_array,
> timestamp_array])
> .expect("created new record batch");
> ```
> This is annoying because the information that `float_field` is a float is
> encoded both in the Schema and the `Float64Array`
> I would much rather rather be able to construct RecordBatches a a builder
> style to avoid the the redundancy and reduce the amount of typing /
> redundancy:
> ```
> let float_array: ArrayRef = Arc::new(Float64Array::from(vec![10.1,
> 20.1, 30.1, 40.1]));
> let timestamp_array: ArrayRef = Arc::new(Int64Array::from(vec![1000,
> 2000, 3000, 4000]));
> let batch = RecordBatch::empty()
> .append("float_field", timestamp_array).unwrap()
> .append("time", float_array).unwrap;
> ```
> The proposal is to add a method to `RecordBatch` like
> ```
> impl RecordBatch {
> ...
> fn append(self, field_name: &str, field_values: ArrayRef) -> Result<Self>
> }
> ```
> That would append the a field name to the current schema, returning an error
> if field_name was already present.
> The nullability of the field would be set based on the actual null count of
> the field_values
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