mz_persist_types/
arrow.rs

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1// Copyright Materialize, Inc. and contributors. All rights reserved.
2//
3// Use of this software is governed by the Business Source License
4// included in the LICENSE file.
5//
6// As of the Change Date specified in that file, in accordance with
7// the Business Source License, use of this software will be governed
8// by the Apache License, Version 2.0.
9
10//! A [protobuf] representation of [Apache Arrow] arrays.
11//!
12//! # Motivation
13//!
14//! Persist can store a small amount of data inline at the consensus layer.
15//! Because we are space constrained, we take particular care to store only the
16//! data that is necessary. Other Arrow serialization formats, e.g. [Parquet]
17//! or [Arrow IPC], include data that we don't need and would be wasteful to
18//! store.
19//!
20//! [protobuf]: https://protobuf.dev/
21//! [Apache Arrow]: https://arrow.apache.org/
22//! [Parquet]: https://parquet.apache.org/docs/
23//! [Arrow IPC]: https://arrow.apache.org/docs/format/Columnar.html#serialization-and-interprocess-communication-ipc
24
25use std::cmp::Ordering;
26use std::fmt::Display;
27use std::sync::Arc;
28
29use arrow::array::*;
30use arrow::buffer::{BooleanBuffer, NullBuffer, OffsetBuffer};
31use arrow::datatypes::{ArrowNativeType, DataType, Field, FieldRef, Fields};
32use itertools::Itertools;
33use mz_ore::cast::CastFrom;
34use mz_ore::soft_assert_eq_no_log;
35use mz_proto::{IntoRustIfSome, ProtoType, RustType, TryFromProtoError};
36use prost::Message;
37
38#[allow(missing_docs)]
39mod proto {
40    include!(concat!(env!("OUT_DIR"), "/mz_persist_types.arrow.rs"));
41}
42use crate::arrow::proto::data_type;
43pub use proto::{DataType as ProtoDataType, ProtoArrayData};
44
45/// Extract the list of fields for our recursive datatypes.
46pub fn fields_for_type(data_type: &DataType) -> &[FieldRef] {
47    match data_type {
48        DataType::Struct(fields) => fields,
49        DataType::List(field) => std::slice::from_ref(field),
50        DataType::Map(field, _) => std::slice::from_ref(field),
51        DataType::Null
52        | DataType::Boolean
53        | DataType::Int8
54        | DataType::Int16
55        | DataType::Int32
56        | DataType::Int64
57        | DataType::UInt8
58        | DataType::UInt16
59        | DataType::UInt32
60        | DataType::UInt64
61        | DataType::Float16
62        | DataType::Float32
63        | DataType::Float64
64        | DataType::Timestamp(_, _)
65        | DataType::Date32
66        | DataType::Date64
67        | DataType::Time32(_)
68        | DataType::Time64(_)
69        | DataType::Duration(_)
70        | DataType::Interval(_)
71        | DataType::Binary
72        | DataType::FixedSizeBinary(_)
73        | DataType::LargeBinary
74        | DataType::BinaryView
75        | DataType::Utf8
76        | DataType::LargeUtf8
77        | DataType::Utf8View
78        | DataType::Decimal128(_, _)
79        | DataType::Decimal256(_, _) => &[],
80        DataType::ListView(_)
81        | DataType::FixedSizeList(_, _)
82        | DataType::LargeList(_)
83        | DataType::LargeListView(_)
84        | DataType::Union(_, _)
85        | DataType::Dictionary(_, _)
86        | DataType::RunEndEncoded(_, _) => unimplemented!("not supported"),
87    }
88}
89
90/// Encode the array into proto. If an expected data type is passed, that implies it is
91/// encoded at some higher level, and we omit it from the data.
92fn into_proto_with_type(data: &ArrayData, expected_type: Option<&DataType>) -> ProtoArrayData {
93    let data_type = match expected_type {
94        Some(expected) => {
95            // Equality is recursive, and this function is itself called recursively,
96            // skip the call in production to avoid a quadratic overhead.
97            soft_assert_eq_no_log!(
98                expected,
99                data.data_type(),
100                "actual type should match expected type"
101            );
102            None
103        }
104        None => Some(data.data_type().into_proto()),
105    };
106
107    ProtoArrayData {
108        data_type,
109        length: u64::cast_from(data.len()),
110        offset: u64::cast_from(data.offset()),
111        buffers: data.buffers().iter().map(|b| b.into_proto()).collect(),
112        children: data
113            .child_data()
114            .iter()
115            .zip_eq(fields_for_type(expected_type.unwrap_or(data.data_type())))
116            .map(|(child, expect)| into_proto_with_type(child, Some(expect.data_type())))
117            .collect(),
118        nulls: data.nulls().map(|n| n.inner().into_proto()),
119    }
120}
121
122/// Decode the array data.
123/// If the data type is omitted from the proto, we decode it as the expected type.
124fn from_proto_with_type(
125    proto: ProtoArrayData,
126    expected_type: Option<&DataType>,
127) -> Result<ArrayData, TryFromProtoError> {
128    let ProtoArrayData {
129        data_type,
130        length,
131        offset,
132        buffers,
133        children,
134        nulls,
135    } = proto;
136    let data_type: Option<DataType> = data_type.into_rust()?;
137    let data_type = match (data_type, expected_type) {
138        (Some(data_type), None) => data_type,
139        (Some(data_type), Some(expected_type)) => {
140            // Equality is recursive, and this function is itself called recursively,
141            // skip the call in production to avoid a quadratic overhead.
142            soft_assert_eq_no_log!(
143                data_type,
144                *expected_type,
145                "expected type should match actual type"
146            );
147            data_type
148        }
149        (None, Some(expected_type)) => expected_type.clone(),
150        (None, None) => {
151            return Err(TryFromProtoError::MissingField(
152                "ProtoArrayData::data_type".to_string(),
153            ));
154        }
155    };
156    let nulls = nulls
157        .map(|n| n.into_rust())
158        .transpose()?
159        .map(NullBuffer::new);
160
161    let mut builder = ArrayDataBuilder::new(data_type.clone())
162        .len(usize::cast_from(length))
163        .offset(usize::cast_from(offset))
164        .nulls(nulls);
165
166    for b in buffers.into_iter().map(|b| b.into_rust()) {
167        builder = builder.add_buffer(b?);
168    }
169    for c in children
170        .into_iter()
171        .zip_eq(fields_for_type(&data_type))
172        .map(|(c, field)| from_proto_with_type(c, Some(field.data_type())))
173    {
174        builder = builder.add_child_data(c?);
175    }
176
177    // Construct the builder which validates all inputs and aligns data.
178    builder
179        .build_aligned()
180        .map_err(|e| TryFromProtoError::RowConversionError(e.to_string()))
181}
182
183impl RustType<ProtoArrayData> for arrow::array::ArrayData {
184    fn into_proto(&self) -> ProtoArrayData {
185        into_proto_with_type(self, None)
186    }
187
188    fn from_proto(proto: ProtoArrayData) -> Result<Self, TryFromProtoError> {
189        from_proto_with_type(proto, None)
190    }
191}
192
193impl RustType<proto::DataType> for arrow::datatypes::DataType {
194    fn into_proto(&self) -> proto::DataType {
195        let kind = match self {
196            DataType::Null => proto::data_type::Kind::Null(()),
197            DataType::Boolean => proto::data_type::Kind::Boolean(()),
198            DataType::UInt8 => proto::data_type::Kind::Uint8(()),
199            DataType::UInt16 => proto::data_type::Kind::Uint16(()),
200            DataType::UInt32 => proto::data_type::Kind::Uint32(()),
201            DataType::UInt64 => proto::data_type::Kind::Uint64(()),
202            DataType::Int8 => proto::data_type::Kind::Int8(()),
203            DataType::Int16 => proto::data_type::Kind::Int16(()),
204            DataType::Int32 => proto::data_type::Kind::Int32(()),
205            DataType::Int64 => proto::data_type::Kind::Int64(()),
206            DataType::Float32 => proto::data_type::Kind::Float32(()),
207            DataType::Float64 => proto::data_type::Kind::Float64(()),
208            DataType::Utf8 => proto::data_type::Kind::String(()),
209            DataType::Binary => proto::data_type::Kind::Binary(()),
210            DataType::FixedSizeBinary(size) => proto::data_type::Kind::FixedBinary(*size),
211            DataType::List(inner) => proto::data_type::Kind::List(Box::new(inner.into_proto())),
212            DataType::Map(inner, sorted) => {
213                let map = proto::data_type::Map {
214                    value: Some(Box::new(inner.into_proto())),
215                    sorted: *sorted,
216                };
217                proto::data_type::Kind::Map(Box::new(map))
218            }
219            DataType::Struct(children) => {
220                let children = children.into_iter().map(|f| f.into_proto()).collect();
221                proto::data_type::Kind::Struct(proto::data_type::Struct { children })
222            }
223            other => unimplemented!("unsupported data type {other:?}"),
224        };
225
226        proto::DataType { kind: Some(kind) }
227    }
228
229    fn from_proto(proto: proto::DataType) -> Result<Self, TryFromProtoError> {
230        let data_type = proto
231            .kind
232            .ok_or_else(|| TryFromProtoError::missing_field("kind"))?;
233        let data_type = match data_type {
234            proto::data_type::Kind::Null(()) => DataType::Null,
235            proto::data_type::Kind::Boolean(()) => DataType::Boolean,
236            proto::data_type::Kind::Uint8(()) => DataType::UInt8,
237            proto::data_type::Kind::Uint16(()) => DataType::UInt16,
238            proto::data_type::Kind::Uint32(()) => DataType::UInt32,
239            proto::data_type::Kind::Uint64(()) => DataType::UInt64,
240            proto::data_type::Kind::Int8(()) => DataType::Int8,
241            proto::data_type::Kind::Int16(()) => DataType::Int16,
242            proto::data_type::Kind::Int32(()) => DataType::Int32,
243            proto::data_type::Kind::Int64(()) => DataType::Int64,
244            proto::data_type::Kind::Float32(()) => DataType::Float32,
245            proto::data_type::Kind::Float64(()) => DataType::Float64,
246            proto::data_type::Kind::String(()) => DataType::Utf8,
247            proto::data_type::Kind::Binary(()) => DataType::Binary,
248            proto::data_type::Kind::FixedBinary(size) => DataType::FixedSizeBinary(size),
249            proto::data_type::Kind::List(inner) => DataType::List(Arc::new((*inner).into_rust()?)),
250            proto::data_type::Kind::Map(inner) => {
251                let value = inner
252                    .value
253                    .ok_or_else(|| TryFromProtoError::missing_field("map.value"))?;
254                DataType::Map(Arc::new((*value).into_rust()?), inner.sorted)
255            }
256            proto::data_type::Kind::Struct(inner) => {
257                let children: Vec<Field> = inner
258                    .children
259                    .into_iter()
260                    .map(|c| c.into_rust())
261                    .collect::<Result<_, _>>()?;
262                DataType::Struct(Fields::from(children))
263            }
264        };
265
266        Ok(data_type)
267    }
268}
269
270impl RustType<proto::Field> for arrow::datatypes::Field {
271    fn into_proto(&self) -> proto::Field {
272        proto::Field {
273            name: self.name().clone(),
274            nullable: self.is_nullable(),
275            data_type: Some(Box::new(self.data_type().into_proto())),
276        }
277    }
278
279    fn from_proto(proto: proto::Field) -> Result<Self, TryFromProtoError> {
280        let proto::Field {
281            name,
282            nullable,
283            data_type,
284        } = proto;
285        let data_type =
286            data_type.ok_or_else(|| TryFromProtoError::missing_field("field.data_type"))?;
287        let data_type = (*data_type).into_rust()?;
288
289        Ok(Field::new(name, data_type, nullable))
290    }
291}
292
293impl RustType<proto::Buffer> for arrow::buffer::Buffer {
294    fn into_proto(&self) -> proto::Buffer {
295        // TODO(parkmycar): There is probably something better we can do here.
296        proto::Buffer {
297            data: bytes::Bytes::copy_from_slice(self.as_slice()),
298        }
299    }
300
301    fn from_proto(proto: proto::Buffer) -> Result<Self, TryFromProtoError> {
302        Ok(arrow::buffer::Buffer::from_bytes(proto.data.into()))
303    }
304}
305
306impl RustType<proto::BooleanBuffer> for arrow::buffer::BooleanBuffer {
307    fn into_proto(&self) -> proto::BooleanBuffer {
308        proto::BooleanBuffer {
309            buffer: Some(self.sliced().into_proto()),
310            length: u64::cast_from(self.len()),
311        }
312    }
313
314    fn from_proto(proto: proto::BooleanBuffer) -> Result<Self, TryFromProtoError> {
315        let proto::BooleanBuffer { buffer, length } = proto;
316        let buffer = buffer.into_rust_if_some("buffer")?;
317        Ok(BooleanBuffer::new(buffer, 0, usize::cast_from(length)))
318    }
319}
320
321/// Wraps a single arrow array, downcasted to a specific type.
322#[derive(Clone, Debug)]
323pub enum ArrayOrd {
324    /// Wraps a `NullArray`.
325    Null(NullArray),
326    /// Wraps a `Bool` array.
327    Bool(BooleanArray),
328    /// Wraps a `Int8` array.
329    Int8(Int8Array),
330    /// Wraps a `Int16` array.
331    Int16(Int16Array),
332    /// Wraps a `Int32` array.
333    Int32(Int32Array),
334    /// Wraps a `Int64` array.
335    Int64(Int64Array),
336    /// Wraps a `UInt8` array.
337    UInt8(UInt8Array),
338    /// Wraps a `UInt16` array.
339    UInt16(UInt16Array),
340    /// Wraps a `UInt32` array.
341    UInt32(UInt32Array),
342    /// Wraps a `UInt64` array.
343    UInt64(UInt64Array),
344    /// Wraps a `Float32` array.
345    Float32(Float32Array),
346    /// Wraps a `Float64` array.
347    Float64(Float64Array),
348    /// Wraps a `String` array.
349    String(StringArray),
350    /// Wraps a `Binary` array.
351    Binary(BinaryArray),
352    /// Wraps a `FixedSizeBinary` array.
353    FixedSizeBinary(FixedSizeBinaryArray),
354    /// Wraps a `List` array.
355    List(Option<NullBuffer>, OffsetBuffer<i32>, Box<ArrayOrd>),
356    /// Wraps a `Struct` array.
357    Struct(Option<NullBuffer>, Vec<ArrayOrd>),
358}
359
360impl ArrayOrd {
361    /// Downcast the provided array to a specific type in our enum.
362    pub fn new(array: &dyn Array) -> Self {
363        match array.data_type() {
364            DataType::Null => ArrayOrd::Null(NullArray::from(array.to_data())),
365            DataType::Boolean => ArrayOrd::Bool(array.as_boolean().clone()),
366            DataType::Int8 => ArrayOrd::Int8(array.as_primitive().clone()),
367            DataType::Int16 => ArrayOrd::Int16(array.as_primitive().clone()),
368            DataType::Int32 => ArrayOrd::Int32(array.as_primitive().clone()),
369            DataType::Int64 => ArrayOrd::Int64(array.as_primitive().clone()),
370            DataType::UInt8 => ArrayOrd::UInt8(array.as_primitive().clone()),
371            DataType::UInt16 => ArrayOrd::UInt16(array.as_primitive().clone()),
372            DataType::UInt32 => ArrayOrd::UInt32(array.as_primitive().clone()),
373            DataType::UInt64 => ArrayOrd::UInt64(array.as_primitive().clone()),
374            DataType::Float32 => ArrayOrd::Float32(array.as_primitive().clone()),
375            DataType::Float64 => ArrayOrd::Float64(array.as_primitive().clone()),
376            DataType::Binary => ArrayOrd::Binary(array.as_binary().clone()),
377            DataType::Utf8 => ArrayOrd::String(array.as_string().clone()),
378            DataType::FixedSizeBinary(_) => {
379                ArrayOrd::FixedSizeBinary(array.as_fixed_size_binary().clone())
380            }
381            DataType::List(_) => {
382                let list_array = array.as_list();
383                ArrayOrd::List(
384                    list_array.nulls().cloned(),
385                    list_array.offsets().clone(),
386                    Box::new(ArrayOrd::new(list_array.values())),
387                )
388            }
389            DataType::Struct(_) => {
390                let struct_array = array.as_struct();
391                let nulls = array.nulls().cloned();
392                let columns: Vec<_> = struct_array
393                    .columns()
394                    .iter()
395                    .map(|a| ArrayOrd::new(a))
396                    .collect();
397                ArrayOrd::Struct(nulls, columns)
398            }
399            data_type => unimplemented!("array type {data_type:?} not yet supported"),
400        }
401    }
402
403    /// Returns the rough amount of space required for the data in this array in bytes.
404    /// (Not counting nulls, dictionary encoding, or other space optimizations.)
405    pub fn goodbytes(&self) -> usize {
406        match self {
407            ArrayOrd::Null(_) => 0,
408            // This is, strictly speaking, wrong - but consistent with `ArrayIdx::goodbytes`,
409            // which counts one byte per bool.
410            ArrayOrd::Bool(b) => b.len(),
411            ArrayOrd::Int8(a) => a.values().inner().len(),
412            ArrayOrd::Int16(a) => a.values().inner().len(),
413            ArrayOrd::Int32(a) => a.values().inner().len(),
414            ArrayOrd::Int64(a) => a.values().inner().len(),
415            ArrayOrd::UInt8(a) => a.values().inner().len(),
416            ArrayOrd::UInt16(a) => a.values().inner().len(),
417            ArrayOrd::UInt32(a) => a.values().inner().len(),
418            ArrayOrd::UInt64(a) => a.values().inner().len(),
419            ArrayOrd::Float32(a) => a.values().inner().len(),
420            ArrayOrd::Float64(a) => a.values().inner().len(),
421            ArrayOrd::String(a) => a.values().len(),
422            ArrayOrd::Binary(a) => a.values().len(),
423            ArrayOrd::FixedSizeBinary(a) => a.values().len(),
424            ArrayOrd::List(_, _, nested) => nested.goodbytes(),
425            ArrayOrd::Struct(_, nested) => nested.iter().map(|a| a.goodbytes()).sum(),
426        }
427    }
428
429    /// Return a struct representing the value at a particular index in this array.
430    pub fn at(&self, idx: usize) -> ArrayIdx {
431        ArrayIdx { idx, array: self }
432    }
433}
434
435/// A struct representing a particular entry in a particular array. Most useful for its `Ord`
436/// implementation, which can compare entire rows across similarly-typed arrays.
437///
438/// It is an error to compare indices from arrays with different types, with one exception:
439/// it is valid to compare two `StructArray`s, one of which is a prefix of the other...
440/// in which case we'll compare the values on that subset of the fields, and the shorter
441/// of the two structs will compare less if they're otherwise equal.
442#[derive(Clone, Copy, Debug)]
443pub struct ArrayIdx<'a> {
444    /// An index into a particular array.
445    pub idx: usize,
446    /// The particular array.
447    pub array: &'a ArrayOrd,
448}
449
450impl Display for ArrayIdx<'_> {
451    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
452        match self.array {
453            ArrayOrd::Null(_) => write!(f, "null"),
454            ArrayOrd::Bool(a) => write!(f, "{}", a.value(self.idx)),
455            ArrayOrd::Int8(a) => write!(f, "{}", a.value(self.idx)),
456            ArrayOrd::Int16(a) => write!(f, "{}", a.value(self.idx)),
457            ArrayOrd::Int32(a) => write!(f, "{}", a.value(self.idx)),
458            ArrayOrd::Int64(a) => write!(f, "{}", a.value(self.idx)),
459            ArrayOrd::UInt8(a) => write!(f, "{}", a.value(self.idx)),
460            ArrayOrd::UInt16(a) => write!(f, "{}", a.value(self.idx)),
461            ArrayOrd::UInt32(a) => write!(f, "{}", a.value(self.idx)),
462            ArrayOrd::UInt64(a) => write!(f, "{}", a.value(self.idx)),
463            ArrayOrd::Float32(a) => write!(f, "{}", a.value(self.idx)),
464            ArrayOrd::Float64(a) => write!(f, "{}", a.value(self.idx)),
465            ArrayOrd::String(a) => write!(f, "{}", a.value(self.idx)),
466            ArrayOrd::Binary(a) => {
467                for byte in a.value(self.idx) {
468                    write!(f, "{:02x}", byte)?;
469                }
470                Ok(())
471            }
472            ArrayOrd::FixedSizeBinary(a) => {
473                for byte in a.value(self.idx) {
474                    write!(f, "{:02x}", byte)?;
475                }
476                Ok(())
477            }
478            ArrayOrd::List(_, offsets, nested) => {
479                write!(
480                    f,
481                    "[{}]",
482                    mz_ore::str::separated(", ", list_range(offsets, nested, self.idx))
483                )
484            }
485            ArrayOrd::Struct(_, nested) => write!(
486                f,
487                "{{{}}}",
488                mz_ore::str::separated(", ", nested.iter().map(|f| f.at(self.idx)))
489            ),
490        }
491    }
492}
493
494#[inline]
495fn list_range<'a>(
496    offsets: &OffsetBuffer<i32>,
497    values: &'a ArrayOrd,
498    idx: usize,
499) -> impl Iterator<Item = ArrayIdx<'a>> + Clone {
500    let offsets = offsets.inner();
501    let from = offsets[idx].as_usize();
502    let to = offsets[idx + 1].as_usize();
503    (from..to).map(|i| values.at(i))
504}
505
506impl<'a> ArrayIdx<'a> {
507    /// Returns the rough amount of space required for this entry in bytes.
508    /// (Not counting nulls, dictionary encoding, or other space optimizations.)
509    pub fn goodbytes(&self) -> usize {
510        match self.array {
511            ArrayOrd::Null(_) => 0,
512            ArrayOrd::Bool(_) => size_of::<bool>(),
513            ArrayOrd::Int8(_) => size_of::<i8>(),
514            ArrayOrd::Int16(_) => size_of::<i16>(),
515            ArrayOrd::Int32(_) => size_of::<i32>(),
516            ArrayOrd::Int64(_) => size_of::<i64>(),
517            ArrayOrd::UInt8(_) => size_of::<u8>(),
518            ArrayOrd::UInt16(_) => size_of::<u16>(),
519            ArrayOrd::UInt32(_) => size_of::<u32>(),
520            ArrayOrd::UInt64(_) => size_of::<u64>(),
521            ArrayOrd::Float32(_) => size_of::<f32>(),
522            ArrayOrd::Float64(_) => size_of::<f64>(),
523            ArrayOrd::String(a) => a.value(self.idx).len(),
524            ArrayOrd::Binary(a) => a.value(self.idx).len(),
525            ArrayOrd::FixedSizeBinary(a) => a.value_length().as_usize(),
526            ArrayOrd::List(_, offsets, nested) => {
527                // Range over the list, summing up the bytes for each entry.
528                list_range(offsets, nested, self.idx)
529                    .map(|a| a.goodbytes())
530                    .sum()
531            }
532            ArrayOrd::Struct(_, nested) => nested.iter().map(|a| a.at(self.idx).goodbytes()).sum(),
533        }
534    }
535}
536
537impl<'a> Ord for ArrayIdx<'a> {
538    fn cmp(&self, other: &Self) -> Ordering {
539        #[inline]
540        fn is_null(buffer: &Option<NullBuffer>, idx: usize) -> bool {
541            buffer.as_ref().map_or(false, |b| b.is_null(idx))
542        }
543        #[inline]
544        fn cmp<A: ArrayAccessor>(
545            left: A,
546            left_idx: usize,
547            right: A,
548            right_idx: usize,
549            cmp: fn(&A::Item, &A::Item) -> Ordering,
550        ) -> Ordering {
551            // NB: nulls sort last, conveniently matching psql / mz_repr
552            match (left.is_null(left_idx), right.is_null(right_idx)) {
553                (false, true) => Ordering::Less,
554                (true, true) => Ordering::Equal,
555                (true, false) => Ordering::Greater,
556                (false, false) => cmp(&left.value(left_idx), &right.value(right_idx)),
557            }
558        }
559        match (&self.array, &other.array) {
560            (ArrayOrd::Null(s), ArrayOrd::Null(o)) => {
561                debug_assert!(
562                    self.idx < s.len() && other.idx < o.len(),
563                    "null array indices in bounds"
564                );
565                Ordering::Equal
566            }
567            // For arrays with "simple" value types, we fetch and compare the underlying values directly.
568            (ArrayOrd::Bool(s), ArrayOrd::Bool(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
569            (ArrayOrd::Int8(s), ArrayOrd::Int8(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
570            (ArrayOrd::Int16(s), ArrayOrd::Int16(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
571            (ArrayOrd::Int32(s), ArrayOrd::Int32(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
572            (ArrayOrd::Int64(s), ArrayOrd::Int64(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
573            (ArrayOrd::UInt8(s), ArrayOrd::UInt8(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
574            (ArrayOrd::UInt16(s), ArrayOrd::UInt16(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
575            (ArrayOrd::UInt32(s), ArrayOrd::UInt32(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
576            (ArrayOrd::UInt64(s), ArrayOrd::UInt64(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
577            (ArrayOrd::Float32(s), ArrayOrd::Float32(o)) => {
578                cmp(s, self.idx, o, other.idx, f32::total_cmp)
579            }
580            (ArrayOrd::Float64(s), ArrayOrd::Float64(o)) => {
581                cmp(s, self.idx, o, other.idx, f64::total_cmp)
582            }
583            (ArrayOrd::String(s), ArrayOrd::String(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
584            (ArrayOrd::Binary(s), ArrayOrd::Binary(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
585            (ArrayOrd::FixedSizeBinary(s), ArrayOrd::FixedSizeBinary(o)) => {
586                cmp(s, self.idx, o, other.idx, Ord::cmp)
587            }
588            // For lists, we generate an iterator for each side that ranges over the correct
589            // indices into the value buffer, then compare them lexicographically.
590            (
591                ArrayOrd::List(s_nulls, s_offset, s_values),
592                ArrayOrd::List(o_nulls, o_offset, o_values),
593            ) => match (is_null(s_nulls, self.idx), is_null(o_nulls, other.idx)) {
594                (false, true) => Ordering::Less,
595                (true, true) => Ordering::Equal,
596                (true, false) => Ordering::Greater,
597                (false, false) => list_range(s_offset, s_values, self.idx)
598                    .cmp(list_range(o_offset, o_values, other.idx)),
599            },
600            // For structs, we iterate over the same index in each field for each input,
601            // comparing them lexicographically in order.
602            (ArrayOrd::Struct(s_nulls, s_cols), ArrayOrd::Struct(o_nulls, o_cols)) => {
603                match (is_null(s_nulls, self.idx), is_null(o_nulls, other.idx)) {
604                    (false, true) => Ordering::Less,
605                    (true, true) => Ordering::Equal,
606                    (true, false) => Ordering::Greater,
607                    (false, false) => {
608                        let s = s_cols.iter().map(|array| array.at(self.idx));
609                        let o = o_cols.iter().map(|array| array.at(other.idx));
610                        s.cmp(o)
611                    }
612                }
613            }
614            (_, _) => panic!("array types did not match"),
615        }
616    }
617}
618
619impl<'a> PartialOrd for ArrayIdx<'a> {
620    fn partial_cmp(&self, other: &ArrayIdx) -> Option<Ordering> {
621        Some(self.cmp(other))
622    }
623}
624
625impl<'a> PartialEq for ArrayIdx<'a> {
626    fn eq(&self, other: &ArrayIdx) -> bool {
627        self.cmp(other) == Ordering::Equal
628    }
629}
630
631impl<'a> Eq for ArrayIdx<'a> {}
632
633/// An array with precisely one entry, for use as a lower bound.
634#[derive(Debug, Clone)]
635pub struct ArrayBound {
636    raw: ArrayRef,
637    ord: ArrayOrd,
638    index: usize,
639}
640
641impl PartialEq for ArrayBound {
642    fn eq(&self, other: &Self) -> bool {
643        self.get().eq(&other.get())
644    }
645}
646
647impl Eq for ArrayBound {}
648
649impl ArrayBound {
650    /// Create a new `ArrayBound` for this array, with the bound at the provided index.
651    pub fn new(array: ArrayRef, index: usize) -> Self {
652        Self {
653            ord: ArrayOrd::new(array.as_ref()),
654            raw: array,
655            index,
656        }
657    }
658
659    /// Get the value of the bound.
660    pub fn get(&self) -> ArrayIdx {
661        self.ord.at(self.index)
662    }
663
664    /// Convert to an array-data proto, respecting a maximum data size. The resulting proto will
665    /// decode to a single-row array, such that `ArrayBound::new(decoded, 0).get() <= self.get()`,
666    /// which makes it suitable as a lower bound.
667    pub fn to_proto_lower(&self, max_len: usize) -> Option<ProtoArrayData> {
668        // Use `take` instead of slice to make sure we encode just the relevant row to proto,
669        // instead of some larger buffer with an offset.
670        let indices = UInt64Array::from_value(u64::usize_as(self.index), 1);
671        let taken = arrow::compute::take(self.raw.as_ref(), &indices, None).ok()?;
672        let array_data = taken.into_data();
673
674        let mut proto = array_data.into_proto();
675        let original_len = proto.encoded_len();
676        if original_len <= max_len {
677            return Some(proto);
678        }
679
680        let mut data_type = proto.data_type.take()?;
681        maybe_trim_proto(&mut data_type, &mut proto, max_len);
682        proto.data_type = Some(data_type);
683
684        if cfg!(debug_assertions) {
685            let array: ArrayData = proto
686                .clone()
687                .into_rust()
688                .expect("trimmed array data can still be decoded");
689            assert_eq!(array.len(), 1);
690            let new_bound = Self::new(make_array(array), 0);
691            assert!(
692                new_bound.get() <= self.get(),
693                "trimmed bound should be comparable to and no larger than the original data"
694            )
695        }
696
697        if proto.encoded_len() <= max_len {
698            Some(proto)
699        } else {
700            None
701        }
702    }
703}
704
705/// Makes a best effort to shrink the proto while preserving the ordering.
706/// (The proto might not be smaller after this method is called, but it should always
707/// be a valid lower bound.)
708///
709/// Note that we pass in the data type and the array data separately, since we only keep
710/// type info at the top level. If a caller does have a top-level `ArrayData` instance,
711/// they should take that type and pass it in separately.
712fn maybe_trim_proto(data_type: &mut proto::DataType, body: &mut ProtoArrayData, max_len: usize) {
713    assert!(body.data_type.is_none(), "expected separate data type");
714    // TODO: consider adding cases for strings and byte arrays
715    let encoded_len = data_type.encoded_len() + body.encoded_len();
716    match &mut data_type.kind {
717        Some(data_type::Kind::Struct(data_type::Struct { children: fields })) => {
718            // Pop off fields one by one, keeping an estimate of the encoded length.
719            let mut struct_len = encoded_len;
720            while struct_len > max_len {
721                let Some(mut child) = body.children.pop() else {
722                    break;
723                };
724                let Some(mut field) = fields.pop() else { break };
725
726                struct_len -= field.encoded_len() + child.encoded_len();
727                if let Some(remaining_len) = max_len.checked_sub(struct_len) {
728                    // We're under budget after removing this field! See if we can
729                    // shrink it to fit, but exit the loop regardless.
730                    let Some(field_type) = field.data_type.as_mut() else {
731                        break;
732                    };
733                    maybe_trim_proto(field_type, &mut child, remaining_len);
734                    if field.encoded_len() + child.encoded_len() <= remaining_len {
735                        fields.push(field);
736                        body.children.push(child);
737                    }
738                    break;
739                }
740            }
741        }
742        _ => {}
743    };
744}
745
746#[cfg(test)]
747mod tests {
748    use crate::arrow::{ArrayBound, ArrayOrd};
749    use arrow::array::{
750        ArrayRef, AsArray, BooleanArray, StringArray, StructArray, UInt64Array, make_array,
751    };
752    use arrow::datatypes::{DataType, Field, Fields};
753    use mz_ore::assert_none;
754    use mz_proto::ProtoType;
755    use std::sync::Arc;
756
757    #[mz_ore::test]
758    fn trim_proto() {
759        let nested_fields: Fields = vec![Field::new("a", DataType::UInt64, true)].into();
760        let array: ArrayRef = Arc::new(StructArray::new(
761            vec![
762                Field::new("a", DataType::UInt64, true),
763                Field::new("b", DataType::Utf8, true),
764                Field::new_struct("c", nested_fields.clone(), true),
765            ]
766            .into(),
767            vec![
768                Arc::new(UInt64Array::from_iter_values([1])),
769                Arc::new(StringArray::from_iter_values(["large".repeat(50)])),
770                Arc::new(StructArray::new_null(nested_fields, 1)),
771            ],
772            None,
773        ));
774        let bound = ArrayBound::new(array, 0);
775
776        assert_none!(bound.to_proto_lower(0));
777        assert_none!(bound.to_proto_lower(1));
778
779        let proto = bound
780            .to_proto_lower(100)
781            .expect("can fit something in less than 100 bytes");
782        let array = make_array(proto.into_rust().expect("valid proto"));
783        assert_eq!(
784            array.as_struct().column_names().as_slice(),
785            &["a"],
786            "only the first column should fit"
787        );
788
789        let proto = bound
790            .to_proto_lower(1000)
791            .expect("can fit everything in less than 1000 bytes");
792        let array = make_array(proto.into_rust().expect("valid proto"));
793        assert_eq!(
794            array.as_struct().column_names().as_slice(),
795            &["a", "b", "c"],
796            "all columns should fit"
797        )
798    }
799
800    #[mz_ore::test]
801    fn struct_ord() {
802        let prefix = StructArray::new(
803            vec![Field::new("a", DataType::UInt64, true)].into(),
804            vec![Arc::new(UInt64Array::from_iter_values([1, 3, 5]))],
805            None,
806        );
807        let full = StructArray::new(
808            vec![
809                Field::new("a", DataType::UInt64, true),
810                Field::new("b", DataType::Utf8, true),
811            ]
812            .into(),
813            vec![
814                Arc::new(UInt64Array::from_iter_values([2, 3, 4])),
815                Arc::new(StringArray::from_iter_values(["a", "b", "c"])),
816            ],
817            None,
818        );
819        let prefix_ord = ArrayOrd::new(&prefix);
820        let full_ord = ArrayOrd::new(&full);
821
822        // Comparison works as normal over the shared columns... but when those columns are identical,
823        // the shorter struct is always smaller.
824        assert!(prefix_ord.at(0) < full_ord.at(0), "(1) < (2, 'a')");
825        assert!(prefix_ord.at(1) < full_ord.at(1), "(3) < (3, 'b')");
826        assert!(prefix_ord.at(2) > full_ord.at(2), "(5) < (4, 'c')");
827    }
828
829    #[mz_ore::test]
830    #[should_panic(expected = "array types did not match")]
831    fn struct_ord_incompat() {
832        // This test is descriptive, not prescriptive: we declare it is an error to compare
833        // structs like this, but not what the result of comparing them is.
834        let string = StructArray::new(
835            vec![
836                Field::new("a", DataType::UInt64, true),
837                Field::new("b", DataType::Utf8, true),
838            ]
839            .into(),
840            vec![
841                Arc::new(UInt64Array::from_iter_values([1])),
842                Arc::new(StringArray::from_iter_values(["a"])),
843            ],
844            None,
845        );
846        let boolean = StructArray::new(
847            vec![
848                Field::new("a", DataType::UInt64, true),
849                Field::new("b", DataType::Boolean, true),
850            ]
851            .into(),
852            vec![
853                Arc::new(UInt64Array::from_iter_values([1])),
854                Arc::new(BooleanArray::from_iter([Some(true)])),
855            ],
856            None,
857        );
858        let string_ord = ArrayOrd::new(&string);
859        let bool_ord = ArrayOrd::new(&boolean);
860
861        // Despite the matching first column, this will panic with a type mismatch.
862        assert!(string_ord.at(0) < bool_ord.at(0));
863    }
864}
mz_persist_types/arrow.rs

mz_persist_types/
arrow.rs
