Add variant_experimental feature to parquet crate
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| Original file line number | Diff line number | Diff line change |
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| // Licensed to the Apache Software Foundation (ASF) under one | ||
| // or more contributor license agreements. See the NOTICE file | ||
| // distributed with this work for additional information | ||
| // regarding copyright ownership. The ASF licenses this file | ||
| // to you under the Apache License, Version 2.0 (the | ||
| // "License"); you may not use this file except in compliance | ||
| // with the License. You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, | ||
| // software distributed under the License is distributed on an | ||
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | ||
| // KIND, either express or implied. See the License for the | ||
| // specific language governing permissions and limitations | ||
| // under the License. | ||
|
|
||
| //! ⚠️ Experimental Support for reading and writing [`Variant`]s to / from Parquet files ⚠️ | ||
| //! | ||
| //! This is a 🚧 Work In Progress | ||
| //! | ||
| //! Note: Requires the `variant` feature of the `parquet` crate to be enabled. | ||
| //! | ||
| //! # Features | ||
| //! * [`Variant`] represents variant value, which can be an object, list, or primitive. | ||
| //! * [`VariantBuilder`] for building `Variant` values. | ||
| //! * [`VariantArray`] for representing a column of Variant values. | ||
| //! * [`compute`] module with functions for manipulating Variants, such as | ||
| //! [`variant_get`] to extracting a value by path and functions to convert | ||
| //! between `Variant` and JSON. | ||
| //! | ||
| //! [Variant Logical Type]: Variant | ||
| //! [`VariantArray`]: compute::VariantArray | ||
| //! [`variant_get`]: compute::variant_get | ||
| //! | ||
| //! # Example: Writing a Parquet file with Variant column | ||
| //! ```rust | ||
| //! # use parquet::variant::compute::{VariantArray, VariantArrayBuilder}; | ||
| //! # use parquet::variant::VariantBuilderExt; | ||
| //! # use std::sync::Arc; | ||
| //! # use arrow_array::{ArrayRef, RecordBatch}; | ||
| //! # use parquet::arrow::ArrowWriter; | ||
| //! # fn main() -> Result<(), parquet::errors::ParquetError> { | ||
| //! // Use the VariantArrayBuilder to build a VariantArray | ||
| //! let mut builder = VariantArrayBuilder::new(3); | ||
| //! // row 1: {"name": "Alice"} | ||
| //! let mut variant_builder = builder.variant_builder(); | ||
| //! variant_builder.new_object().with_field("name", "Alice").finish()?; | ||
| //! variant_builder.finish(); | ||
| //! let array = builder.build(); | ||
| //! | ||
| //! // TODO support writing VariantArray directly | ||
|
There was a problem hiding this comment. I will file a follow on ticket for this problem |
||
| //! // at the moment it panics when trying to downcast to a struct array | ||
| //! // let array: ArrayRef = Arc::new(array); | ||
| //! let array: ArrayRef = Arc::new(array.into_inner()); | ||
| //! | ||
| //! // create a RecordBatch with the VariantArray | ||
| //! let batch = RecordBatch::try_from_iter(vec![("data", array)])?; | ||
| //! | ||
| //! // write the RecordBatch to a Parquet file | ||
| //! let file = std::fs::File::create("variant.parquet")?; | ||
| //! let mut writer = ArrowWriter::try_new(file, batch.schema(), None)?; | ||
| //! writer.write(&batch)?; | ||
| //! writer.close()?; | ||
| //! | ||
| //! # Ok(()) | ||
| //! # } | ||
| //! ``` | ||
| //! | ||
| //! # Example: Writing JSON with a Parquet file with Variant column | ||
| //! ```rust | ||
| //! # use std::sync::Arc; | ||
| //! # use arrow_array::{ArrayRef, RecordBatch, StringArray}; | ||
| //! # use parquet::variant::compute::batch_json_string_to_variant; | ||
| //! # use parquet::variant::compute::VariantArray; | ||
| //! # use parquet::arrow::ArrowWriter; | ||
| //! # fn main() -> Result<(), parquet::errors::ParquetError> { | ||
| //! // Create an array of JSON strings, simulating a column of JSON data | ||
| //! // TODO use StringViewArray when available | ||
| //! let input_array = StringArray::from(vec![ | ||
| //! Some(r#"{"name": "Alice", "age": 30}"#), | ||
| //! Some(r#"{"name": "Bob", "age": 25, "address": {"city": "New York"}}"#), | ||
| //! None, | ||
| //! Some("{}"), | ||
| //! ]); | ||
| //! let input_array: ArrayRef = Arc::new(input_array); | ||
| //! | ||
| //! // Convert the JSON strings to a VariantArray | ||
| //! let array: VariantArray = batch_json_string_to_variant(&input_array)?; | ||
| //! | ||
| //! // TODO support writing VariantArray directly | ||
| //! // at the moment it panics when trying to downcast to a struct array | ||
| //! // let array: ArrayRef = Arc::new(array); | ||
| //! let array: ArrayRef = Arc::new(array.into_inner()); | ||
| //! | ||
| //! // create a RecordBatch with the VariantArray | ||
| //! let batch = RecordBatch::try_from_iter(vec![("data", array)])?; | ||
| //! | ||
| //! // write the RecordBatch to a Parquet file | ||
| //! let file = std::fs::File::create("variant-json.parquet")?; | ||
|
There was a problem hiding this comment. This is kind of neat to see the data written. I looked at the resulting file using > select * from 'parquet/variant-json.parquet';
+-----------------------------------------------------------------------------------------------------------------------------------+
| data |
+-----------------------------------------------------------------------------------------------------------------------------------+
| {metadata: 11020003076167656e616d65, value: 020200010002080c1e15416c696365} |
| {metadata: 010400040b0e1263697479616464726573736167656e616d65, value: 0203010203000e10140201000009214e657720596f726b0c190d426f62} |
| {metadata: 010000, value: 020000} |
| {metadata: 010000, value: 020000} |
+-----------------------------------------------------------------------------------------------------------------------------------+
4 row(s) fetched.
Elapsed 0.003 seconds. |
||
| //! let mut writer = ArrowWriter::try_new(file, batch.schema(), None)?; | ||
| //! writer.write(&batch)?; | ||
| //! writer.close()?; | ||
| //! # Ok(()) | ||
| //! # } | ||
| //! ``` | ||
| //! | ||
| //! # Example: Reading a Parquet file with Variant column | ||
| //! (TODO: add example) | ||
| pub use parquet_variant::*; | ||
| pub use parquet_variant_compute as compute; | ||
File renamed without changes.
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Being able to write this example is the largest rationale in my mind for the feature flag in the parquet crate