Map AvroSchema to Arrow (#4886) #5009
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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. | ||
|
|
||
| use crate::schema::{Attributes, ComplexType, PrimitiveType, Record, Schema, TypeName}; | ||
| use arrow_schema::{ | ||
| ArrowError, DataType, Field, FieldRef, IntervalUnit, SchemaBuilder, SchemaRef, TimeUnit, | ||
| }; | ||
| use std::borrow::Cow; | ||
| use std::collections::HashMap; | ||
| use std::sync::Arc; | ||
|
|
||
| /// Avro types are not nullable, with nullability instead encoded as a union | ||
| /// where one of the variants is the null type. | ||
| /// | ||
| /// To accommodate this we special case two-variant unions where one of the | ||
| /// variants is the null type, and use this to derive arrow's notion of nullability | ||
| #[derive(Debug, Copy, Clone)] | ||
| enum Nulls { | ||
| /// The nulls are encoded as the first union variant | ||
| NullFirst, | ||
| /// The nulls are encoded as the second union variant | ||
| NullSecond, | ||
| } | ||
|
|
||
| /// An Avro datatype mapped to the arrow data model | ||
| #[derive(Debug, Clone)] | ||
| pub struct AvroDataType { | ||
| nulls: Option<Nulls>, | ||
| metadata: HashMap<String, String>, | ||
| codec: Codec, | ||
| } | ||
|
|
||
| impl AvroDataType { | ||
| /// Returns an arrow [`Field`] with the given name | ||
| pub fn field_with_name(&self, name: &str) -> Field { | ||
| let d = self.codec.data_type(); | ||
| Field::new(name, d, self.nulls.is_some()).with_metadata(self.metadata.clone()) | ||
| } | ||
| } | ||
|
|
||
| /// A named [`AvroDataType`] | ||
| #[derive(Debug, Clone)] | ||
| pub struct AvroField { | ||
| name: String, | ||
| data_type: AvroDataType, | ||
| } | ||
|
|
||
| impl AvroField { | ||
| /// Returns the arrow [`Field`] | ||
| pub fn field(&self) -> Field { | ||
| self.data_type.field_with_name(&self.name) | ||
| } | ||
|
|
||
| /// Returns the [`Codec`] | ||
| pub fn codec(&self) -> &Codec { | ||
| &self.data_type.codec | ||
| } | ||
| } | ||
|
|
||
| impl<'a> TryFrom<&Schema<'a>> for AvroField { | ||
| type Error = ArrowError; | ||
|
|
||
| fn try_from(schema: &Schema<'a>) -> Result<Self, Self::Error> { | ||
| match schema { | ||
| Schema::Complex(ComplexType::Record(r)) => { | ||
| let mut resolver = Resolver::default(); | ||
| let data_type = make_data_type(schema, None, &mut resolver)?; | ||
| Ok(AvroField { | ||
| data_type, | ||
| name: r.name.to_string(), | ||
| }) | ||
| } | ||
| _ => Err(ArrowError::ParseError(format!( | ||
| "Expected record got {schema:?}" | ||
| ))), | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /// An Avro encoding | ||
| /// | ||
| /// <https://avro.apache.org/docs/1.11.1/specification/#encodings> | ||
| #[derive(Debug, Clone)] | ||
| pub enum Codec { | ||
| Null, | ||
| Boolean, | ||
| Int32, | ||
| Int64, | ||
| Float32, | ||
| Float64, | ||
| Binary, | ||
| Utf8, | ||
| Date32, | ||
| TimeMillis, | ||
| TimeMicros, | ||
| /// TimestampMillis(is_utc) | ||
| TimestampMillis(bool), | ||
| /// TimestampMicros(is_utc) | ||
| TimestampMicros(bool), | ||
| Fixed(i32), | ||
| List(Arc<AvroDataType>), | ||
| Struct(Arc<[AvroField]>), | ||
| Duration, | ||
| } | ||
|
|
||
| impl Codec { | ||
| fn data_type(&self) -> DataType { | ||
| match self { | ||
| Self::Null => DataType::Null, | ||
| Self::Boolean => DataType::Boolean, | ||
| Self::Int32 => DataType::Int32, | ||
| Self::Int64 => DataType::Int64, | ||
| Self::Float32 => DataType::Float32, | ||
| Self::Float64 => DataType::Float64, | ||
| Self::Binary => DataType::Binary, | ||
| Self::Utf8 => DataType::Utf8, | ||
| Self::Date32 => DataType::Date32, | ||
| Self::TimeMillis => DataType::Time32(TimeUnit::Millisecond), | ||
| Self::TimeMicros => DataType::Time64(TimeUnit::Microsecond), | ||
| Self::TimestampMillis(is_utc) => { | ||
| DataType::Timestamp(TimeUnit::Millisecond, is_utc.then(|| "+00:00".into())) | ||
| } | ||
| Self::TimestampMicros(is_utc) => { | ||
| DataType::Timestamp(TimeUnit::Microsecond, is_utc.then(|| "+00:00".into())) | ||
| } | ||
| Self::Duration => DataType::Interval(IntervalUnit::MonthDayNano), | ||
| Self::Fixed(size) => DataType::FixedSizeBinary(*size), | ||
| Self::List(f) => DataType::List(Arc::new(f.field_with_name("item"))), | ||
| Self::Struct(f) => DataType::Struct(f.iter().map(|x| x.field()).collect()), | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl From<PrimitiveType> for Codec { | ||
| fn from(value: PrimitiveType) -> Self { | ||
| match value { | ||
| PrimitiveType::Null => Self::Null, | ||
| PrimitiveType::Boolean => Self::Boolean, | ||
| PrimitiveType::Int => Self::Int32, | ||
| PrimitiveType::Long => Self::Int64, | ||
| PrimitiveType::Float => Self::Float32, | ||
| PrimitiveType::Double => Self::Float64, | ||
| PrimitiveType::Bytes => Self::Binary, | ||
| PrimitiveType::String => Self::Utf8, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /// Resolves Avro type names to [`AvroDataType`] | ||
| /// | ||
| /// See <https://avro.apache.org/docs/1.11.1/specification/#names> | ||
| #[derive(Debug, Default)] | ||
| struct Resolver<'a> { | ||
| map: HashMap<(&'a str, &'a str), AvroDataType>, | ||
| } | ||
|
|
||
| impl<'a> Resolver<'a> { | ||
| fn register(&mut self, name: &'a str, namespace: Option<&'a str>, schema: AvroDataType) { | ||
| self.map.insert((name, namespace.unwrap_or("")), schema); | ||
| } | ||
|
|
||
| fn resolve(&self, name: &str, namespace: Option<&'a str>) -> Result<AvroDataType, ArrowError> { | ||
| let (namespace, name) = name | ||
| .rsplit_once('.') | ||
| .unwrap_or_else(|| (namespace.unwrap_or(""), name)); | ||
|
|
||
| self.map | ||
| .get(&(namespace, name)) | ||
| .ok_or_else(|| ArrowError::ParseError(format!("Failed to resolve {namespace}.{name}"))) | ||
| .cloned() | ||
| } | ||
| } | ||
|
|
||
| /// Parses a [`AvroDataType`] from the provided [`Schema`] and the given `name` and `namespace` | ||
| /// | ||
| /// `name`: is name used to refer to `schema` in its parent | ||
| /// `namespace`: an optional qualifier used as part of a type hierarchy | ||
| /// | ||
| /// See [`Resolver`] for more information | ||
| fn make_data_type<'a>( | ||
| schema: &Schema<'a>, | ||
| namespace: Option<&'a str>, | ||
| resolver: &mut Resolver<'a>, | ||
| ) -> Result<AvroDataType, ArrowError> { | ||
| match schema { | ||
| Schema::TypeName(TypeName::Primitive(p)) => Ok(AvroDataType { | ||
| nulls: None, | ||
| metadata: Default::default(), | ||
| codec: (*p).into(), | ||
| }), | ||
| Schema::TypeName(TypeName::Ref(name)) => resolver.resolve(name, namespace), | ||
| Schema::Union(f) => { | ||
| // Special case the common case of nullable primitives | ||
| let null = f | ||
| .iter() | ||
| .position(|x| x == &Schema::TypeName(TypeName::Primitive(PrimitiveType::Null))); | ||
| match (f.len() == 2, null) { | ||
| (true, Some(0)) => { | ||
| let mut field = make_data_type(&f[1], namespace, resolver)?; | ||
| field.nulls = Some(Nulls::NullFirst); | ||
| Ok(field) | ||
| } | ||
| (true, Some(1)) => { | ||
| let mut field = make_data_type(&f[0], namespace, resolver)?; | ||
| field.nulls = Some(Nulls::NullSecond); | ||
| Ok(field) | ||
| } | ||
| _ => Err(ArrowError::NotYetImplemented(format!( | ||
| "Union of {f:?} not currently supported" | ||
| ))), | ||
| } | ||
| } | ||
| Schema::Complex(c) => match c { | ||
| ComplexType::Record(r) => { | ||
| let namespace = r.namespace.or(namespace); | ||
| let fields = r | ||
| .fields | ||
| .iter() | ||
| .map(|field| { | ||
| Ok(AvroField { | ||
| name: field.name.to_string(), | ||
| data_type: make_data_type(&field.r#type, namespace, resolver)?, | ||
| }) | ||
| }) | ||
| .collect::<Result<_, ArrowError>>()?; | ||
|
|
||
| let field = AvroDataType { | ||
| nulls: None, | ||
| codec: Codec::Struct(fields), | ||
| metadata: r.attributes.field_metadata(), | ||
| }; | ||
| resolver.register(r.name, namespace, field.clone()); | ||
| Ok(field) | ||
| } | ||
| ComplexType::Array(a) => { | ||
| let mut field = make_data_type(a.items.as_ref(), namespace, resolver)?; | ||
| Ok(AvroDataType { | ||
| nulls: None, | ||
| metadata: a.attributes.field_metadata(), | ||
| codec: Codec::List(Arc::new(field)), | ||
| }) | ||
| } | ||
| ComplexType::Fixed(f) => { | ||
| let size = f.size.try_into().map_err(|e| { | ||
| ArrowError::ParseError(format!("Overflow converting size to i32: {e}")) | ||
| })?; | ||
|
|
||
| let field = AvroDataType { | ||
| nulls: None, | ||
| metadata: f.attributes.field_metadata(), | ||
| codec: Codec::Fixed(size), | ||
| }; | ||
| resolver.register(f.name, namespace, field.clone()); | ||
| Ok(field) | ||
| } | ||
| ComplexType::Enum(e) => Err(ArrowError::NotYetImplemented(format!( | ||
| "Enum of {e:?} not currently supported" | ||
| ))), | ||
| ComplexType::Map(m) => Err(ArrowError::NotYetImplemented(format!( | ||
| "Map of {m:?} not currently supported" | ||
| ))), | ||
| }, | ||
| Schema::Type(t) => { | ||
| let mut field = | ||
| make_data_type(&Schema::TypeName(t.r#type.clone()), namespace, resolver)?; | ||
|
|
||
| // https://avro.apache.org/docs/1.11.1/specification/#logical-types | ||
| match (t.attributes.logical_type, &mut field.codec) { | ||
| (Some("decimal"), c @ Codec::Fixed(_)) => { | ||
| return Err(ArrowError::NotYetImplemented( | ||
| "Decimals are not currently supported".to_string(), | ||
| )) | ||
| } | ||
| (Some("date"), c @ Codec::Int32) => *c = Codec::Date32, | ||
| (Some("time-millis"), c @ Codec::Int32) => *c = Codec::TimeMillis, | ||
| (Some("time-micros"), c @ Codec::Int64) => *c = Codec::TimeMicros, | ||
| (Some("timestamp-millis"), c @ Codec::Int64) => *c = Codec::TimestampMillis(true), | ||
| (Some("timestamp-micros"), c @ Codec::Int64) => *c = Codec::TimestampMicros(true), | ||
| (Some("local-timestamp-millis"), c @ Codec::Int64) => { | ||
| *c = Codec::TimestampMillis(false) | ||
| } | ||
| (Some("local-timestamp-micros"), c @ Codec::Int64) => { | ||
| *c = Codec::TimestampMicros(false) | ||
| } | ||
| (Some("duration"), c @ Codec::Fixed(12)) => *c = Codec::Duration, | ||
| (Some(logical), _) => { | ||
| // Insert unrecognized logical type into metadata map | ||
| field.metadata.insert("logicalType".into(), logical.into()); | ||
| } | ||
| (None, _) => {} | ||
| } | ||
|
|
||
| if !t.attributes.additional.is_empty() { | ||
| for (k, v) in &t.attributes.additional { | ||
| field.metadata.insert(k.to_string(), v.to_string()); | ||
| } | ||
| } | ||
| Ok(field) | ||
| } | ||
| } | ||
| } | ||
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This whole setup is rather annoying, but necessary to provide a reasonable API