mz_persist_types/
arrow.rs

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(
116                expected_type.unwrap_or_else(|| data.data_type()),
117            ))
118            .map(|(child, expect)| into_proto_with_type(child, Some(expect.data_type())))
119            .collect(),
120        nulls: data.nulls().map(|n| n.inner().into_proto()),
121    }
122}
123
124/// Decode the array data.
125/// If the data type is omitted from the proto, we decode it as the expected type.
126fn from_proto_with_type(
127    proto: ProtoArrayData,
128    expected_type: Option<&DataType>,
129) -> Result<ArrayData, TryFromProtoError> {
130    let ProtoArrayData {
131        data_type,
132        length,
133        offset,
134        buffers,
135        children,
136        nulls,
137    } = proto;
138    let data_type: Option<DataType> = data_type.into_rust()?;
139    let data_type = match (data_type, expected_type) {
140        (Some(data_type), None) => data_type,
141        (Some(data_type), Some(expected_type)) => {
142            // Equality is recursive, and this function is itself called recursively,
143            // skip the call in production to avoid a quadratic overhead.
144            soft_assert_eq_no_log!(
145                data_type,
146                *expected_type,
147                "expected type should match actual type"
148            );
149            data_type
150        }
151        (None, Some(expected_type)) => expected_type.clone(),
152        (None, None) => {
153            return Err(TryFromProtoError::MissingField(
154                "ProtoArrayData::data_type".to_string(),
155            ));
156        }
157    };
158    let nulls = nulls
159        .map(|n| n.into_rust())
160        .transpose()?
161        .map(NullBuffer::new);
162
163    let mut builder = ArrayDataBuilder::new(data_type.clone())
164        .len(usize::cast_from(length))
165        .offset(usize::cast_from(offset))
166        .nulls(nulls);
167
168    for b in buffers.into_iter().map(|b| b.into_rust()) {
169        builder = builder.add_buffer(b?);
170    }
171    for c in children
172        .into_iter()
173        .zip_eq(fields_for_type(&data_type))
174        .map(|(c, field)| from_proto_with_type(c, Some(field.data_type())))
175    {
176        builder = builder.add_child_data(c?);
177    }
178
179    // Construct the builder which validates all inputs and aligns data.
180    builder
181        .align_buffers(true)
182        .build()
183        .map_err(|e| TryFromProtoError::RowConversionError(e.to_string()))
184}
185
186impl RustType<ProtoArrayData> for arrow::array::ArrayData {
187    fn into_proto(&self) -> ProtoArrayData {
188        into_proto_with_type(self, None)
189    }
190
191    fn from_proto(proto: ProtoArrayData) -> Result<Self, TryFromProtoError> {
192        from_proto_with_type(proto, None)
193    }
194}
195
196impl RustType<proto::DataType> for arrow::datatypes::DataType {
197    fn into_proto(&self) -> proto::DataType {
198        let kind = match self {
199            DataType::Null => proto::data_type::Kind::Null(()),
200            DataType::Boolean => proto::data_type::Kind::Boolean(()),
201            DataType::UInt8 => proto::data_type::Kind::Uint8(()),
202            DataType::UInt16 => proto::data_type::Kind::Uint16(()),
203            DataType::UInt32 => proto::data_type::Kind::Uint32(()),
204            DataType::UInt64 => proto::data_type::Kind::Uint64(()),
205            DataType::Int8 => proto::data_type::Kind::Int8(()),
206            DataType::Int16 => proto::data_type::Kind::Int16(()),
207            DataType::Int32 => proto::data_type::Kind::Int32(()),
208            DataType::Int64 => proto::data_type::Kind::Int64(()),
209            DataType::Float32 => proto::data_type::Kind::Float32(()),
210            DataType::Float64 => proto::data_type::Kind::Float64(()),
211            DataType::Utf8 => proto::data_type::Kind::String(()),
212            DataType::Binary => proto::data_type::Kind::Binary(()),
213            DataType::FixedSizeBinary(size) => proto::data_type::Kind::FixedBinary(*size),
214            DataType::List(inner) => proto::data_type::Kind::List(Box::new(inner.into_proto())),
215            DataType::Map(inner, sorted) => {
216                let map = proto::data_type::Map {
217                    value: Some(Box::new(inner.into_proto())),
218                    sorted: *sorted,
219                };
220                proto::data_type::Kind::Map(Box::new(map))
221            }
222            DataType::Struct(children) => {
223                let children = children.into_iter().map(|f| f.into_proto()).collect();
224                proto::data_type::Kind::Struct(proto::data_type::Struct { children })
225            }
226            other => unimplemented!("unsupported data type {other:?}"),
227        };
228
229        proto::DataType { kind: Some(kind) }
230    }
231
232    fn from_proto(proto: proto::DataType) -> Result<Self, TryFromProtoError> {
233        let data_type = proto
234            .kind
235            .ok_or_else(|| TryFromProtoError::missing_field("kind"))?;
236        let data_type = match data_type {
237            proto::data_type::Kind::Null(()) => DataType::Null,
238            proto::data_type::Kind::Boolean(()) => DataType::Boolean,
239            proto::data_type::Kind::Uint8(()) => DataType::UInt8,
240            proto::data_type::Kind::Uint16(()) => DataType::UInt16,
241            proto::data_type::Kind::Uint32(()) => DataType::UInt32,
242            proto::data_type::Kind::Uint64(()) => DataType::UInt64,
243            proto::data_type::Kind::Int8(()) => DataType::Int8,
244            proto::data_type::Kind::Int16(()) => DataType::Int16,
245            proto::data_type::Kind::Int32(()) => DataType::Int32,
246            proto::data_type::Kind::Int64(()) => DataType::Int64,
247            proto::data_type::Kind::Float32(()) => DataType::Float32,
248            proto::data_type::Kind::Float64(()) => DataType::Float64,
249            proto::data_type::Kind::String(()) => DataType::Utf8,
250            proto::data_type::Kind::Binary(()) => DataType::Binary,
251            proto::data_type::Kind::FixedBinary(size) => DataType::FixedSizeBinary(size),
252            proto::data_type::Kind::List(inner) => DataType::List(Arc::new((*inner).into_rust()?)),
253            proto::data_type::Kind::Map(inner) => {
254                let value = inner
255                    .value
256                    .ok_or_else(|| TryFromProtoError::missing_field("map.value"))?;
257                DataType::Map(Arc::new((*value).into_rust()?), inner.sorted)
258            }
259            proto::data_type::Kind::Struct(inner) => {
260                let children: Vec<Field> = inner
261                    .children
262                    .into_iter()
263                    .map(|c| c.into_rust())
264                    .collect::<Result<_, _>>()?;
265                DataType::Struct(Fields::from(children))
266            }
267        };
268
269        Ok(data_type)
270    }
271}
272
273impl RustType<proto::Field> for arrow::datatypes::Field {
274    fn into_proto(&self) -> proto::Field {
275        proto::Field {
276            name: self.name().clone(),
277            nullable: self.is_nullable(),
278            data_type: Some(Box::new(self.data_type().into_proto())),
279        }
280    }
281
282    fn from_proto(proto: proto::Field) -> Result<Self, TryFromProtoError> {
283        let proto::Field {
284            name,
285            nullable,
286            data_type,
287        } = proto;
288        let data_type =
289            data_type.ok_or_else(|| TryFromProtoError::missing_field("field.data_type"))?;
290        let data_type = (*data_type).into_rust()?;
291
292        Ok(Field::new(name, data_type, nullable))
293    }
294}
295
296impl RustType<proto::Buffer> for arrow::buffer::Buffer {
297    fn into_proto(&self) -> proto::Buffer {
298        // Wrapping since arrow's buffer doesn't implement AsRef, though the deref impl exists.
299        #[repr(transparent)]
300        struct BufferWrapper(arrow::buffer::Buffer);
301        impl AsRef<[u8]> for BufferWrapper {
302            fn as_ref(&self) -> &[u8] {
303                &*self.0
304            }
305        }
306        proto::Buffer {
307            data: bytes::Bytes::from_owner(BufferWrapper(self.clone())),
308        }
309    }
310
311    fn from_proto(proto: proto::Buffer) -> Result<Self, TryFromProtoError> {
312        Ok(arrow::buffer::Buffer::from(proto.data))
313    }
314}
315
316impl RustType<proto::BooleanBuffer> for arrow::buffer::BooleanBuffer {
317    fn into_proto(&self) -> proto::BooleanBuffer {
318        proto::BooleanBuffer {
319            buffer: Some(self.sliced().into_proto()),
320            length: u64::cast_from(self.len()),
321        }
322    }
323
324    fn from_proto(proto: proto::BooleanBuffer) -> Result<Self, TryFromProtoError> {
325        let proto::BooleanBuffer { buffer, length } = proto;
326        let buffer = buffer.into_rust_if_some("buffer")?;
327        Ok(BooleanBuffer::new(buffer, 0, usize::cast_from(length)))
328    }
329}
330
331/// Wraps a single arrow array, downcasted to a specific type.
332#[derive(Clone, Debug)]
333pub enum ArrayOrd {
334    /// Wraps a `NullArray`.
335    Null(NullArray),
336    /// Wraps a `Bool` array.
337    Bool(BooleanArray),
338    /// Wraps a `Int8` array.
339    Int8(Int8Array),
340    /// Wraps a `Int16` array.
341    Int16(Int16Array),
342    /// Wraps a `Int32` array.
343    Int32(Int32Array),
344    /// Wraps a `Int64` array.
345    Int64(Int64Array),
346    /// Wraps a `UInt8` array.
347    UInt8(UInt8Array),
348    /// Wraps a `UInt16` array.
349    UInt16(UInt16Array),
350    /// Wraps a `UInt32` array.
351    UInt32(UInt32Array),
352    /// Wraps a `UInt64` array.
353    UInt64(UInt64Array),
354    /// Wraps a `Float32` array.
355    Float32(Float32Array),
356    /// Wraps a `Float64` array.
357    Float64(Float64Array),
358    /// Wraps a `String` array.
359    String(StringArray),
360    /// Wraps a `Binary` array.
361    Binary(BinaryArray),
362    /// Wraps a `FixedSizeBinary` array.
363    FixedSizeBinary(FixedSizeBinaryArray),
364    /// Wraps a `List` array.
365    List(Option<NullBuffer>, OffsetBuffer<i32>, Box<ArrayOrd>),
366    /// Wraps a `Struct` array.
367    Struct(Option<NullBuffer>, Vec<ArrayOrd>),
368}
369
370impl ArrayOrd {
371    /// Downcast the provided array to a specific type in our enum.
372    pub fn new(array: &dyn Array) -> Self {
373        match array.data_type() {
374            DataType::Null => ArrayOrd::Null(NullArray::from(array.to_data())),
375            DataType::Boolean => ArrayOrd::Bool(array.as_boolean().clone()),
376            DataType::Int8 => ArrayOrd::Int8(array.as_primitive().clone()),
377            DataType::Int16 => ArrayOrd::Int16(array.as_primitive().clone()),
378            DataType::Int32 => ArrayOrd::Int32(array.as_primitive().clone()),
379            DataType::Int64 => ArrayOrd::Int64(array.as_primitive().clone()),
380            DataType::UInt8 => ArrayOrd::UInt8(array.as_primitive().clone()),
381            DataType::UInt16 => ArrayOrd::UInt16(array.as_primitive().clone()),
382            DataType::UInt32 => ArrayOrd::UInt32(array.as_primitive().clone()),
383            DataType::UInt64 => ArrayOrd::UInt64(array.as_primitive().clone()),
384            DataType::Float32 => ArrayOrd::Float32(array.as_primitive().clone()),
385            DataType::Float64 => ArrayOrd::Float64(array.as_primitive().clone()),
386            DataType::Binary => ArrayOrd::Binary(array.as_binary().clone()),
387            DataType::Utf8 => ArrayOrd::String(array.as_string().clone()),
388            DataType::FixedSizeBinary(_) => {
389                ArrayOrd::FixedSizeBinary(array.as_fixed_size_binary().clone())
390            }
391            DataType::List(_) => {
392                let list_array = array.as_list();
393                ArrayOrd::List(
394                    list_array.nulls().cloned(),
395                    list_array.offsets().clone(),
396                    Box::new(ArrayOrd::new(list_array.values())),
397                )
398            }
399            DataType::Struct(_) => {
400                let struct_array = array.as_struct();
401                let nulls = array.nulls().cloned();
402                let columns: Vec<_> = struct_array
403                    .columns()
404                    .iter()
405                    .map(|a| ArrayOrd::new(a))
406                    .collect();
407                ArrayOrd::Struct(nulls, columns)
408            }
409            data_type => unimplemented!("array type {data_type:?} not yet supported"),
410        }
411    }
412
413    /// Returns the rough amount of space required for the data in this array in bytes.
414    /// (Not counting nulls, dictionary encoding, or other space optimizations.)
415    pub fn goodbytes(&self) -> usize {
416        match self {
417            ArrayOrd::Null(_) => 0,
418            // This is, strictly speaking, wrong - but consistent with `ArrayIdx::goodbytes`,
419            // which counts one byte per bool.
420            ArrayOrd::Bool(b) => b.len(),
421            ArrayOrd::Int8(a) => a.values().inner().len(),
422            ArrayOrd::Int16(a) => a.values().inner().len(),
423            ArrayOrd::Int32(a) => a.values().inner().len(),
424            ArrayOrd::Int64(a) => a.values().inner().len(),
425            ArrayOrd::UInt8(a) => a.values().inner().len(),
426            ArrayOrd::UInt16(a) => a.values().inner().len(),
427            ArrayOrd::UInt32(a) => a.values().inner().len(),
428            ArrayOrd::UInt64(a) => a.values().inner().len(),
429            ArrayOrd::Float32(a) => a.values().inner().len(),
430            ArrayOrd::Float64(a) => a.values().inner().len(),
431            ArrayOrd::String(a) => a.values().len(),
432            ArrayOrd::Binary(a) => a.values().len(),
433            ArrayOrd::FixedSizeBinary(a) => a.values().len(),
434            ArrayOrd::List(_, _, nested) => nested.goodbytes(),
435            ArrayOrd::Struct(_, nested) => nested.iter().map(|a| a.goodbytes()).sum(),
436        }
437    }
438
439    /// Return a struct representing the value at a particular index in this array.
440    pub fn at(&self, idx: usize) -> ArrayIdx<'_> {
441        ArrayIdx { idx, array: self }
442    }
443}
444
445/// A struct representing a particular entry in a particular array. Most useful for its `Ord`
446/// implementation, which can compare entire rows across similarly-typed arrays.
447///
448/// It is an error to compare indices from arrays with different types, with one exception:
449/// it is valid to compare two `StructArray`s, one of which is a prefix of the other...
450/// in which case we'll compare the values on that subset of the fields, and the shorter
451/// of the two structs will compare less if they're otherwise equal.
452#[derive(Clone, Copy, Debug)]
453pub struct ArrayIdx<'a> {
454    /// An index into a particular array.
455    pub idx: usize,
456    /// The particular array.
457    pub array: &'a ArrayOrd,
458}
459
460impl Display for ArrayIdx<'_> {
461    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
462        match self.array {
463            ArrayOrd::Null(_) => write!(f, "null"),
464            ArrayOrd::Bool(a) => write!(f, "{}", a.value(self.idx)),
465            ArrayOrd::Int8(a) => write!(f, "{}", a.value(self.idx)),
466            ArrayOrd::Int16(a) => write!(f, "{}", a.value(self.idx)),
467            ArrayOrd::Int32(a) => write!(f, "{}", a.value(self.idx)),
468            ArrayOrd::Int64(a) => write!(f, "{}", a.value(self.idx)),
469            ArrayOrd::UInt8(a) => write!(f, "{}", a.value(self.idx)),
470            ArrayOrd::UInt16(a) => write!(f, "{}", a.value(self.idx)),
471            ArrayOrd::UInt32(a) => write!(f, "{}", a.value(self.idx)),
472            ArrayOrd::UInt64(a) => write!(f, "{}", a.value(self.idx)),
473            ArrayOrd::Float32(a) => write!(f, "{}", a.value(self.idx)),
474            ArrayOrd::Float64(a) => write!(f, "{}", a.value(self.idx)),
475            ArrayOrd::String(a) => write!(f, "{}", a.value(self.idx)),
476            ArrayOrd::Binary(a) => {
477                for byte in a.value(self.idx) {
478                    write!(f, "{:02x}", byte)?;
479                }
480                Ok(())
481            }
482            ArrayOrd::FixedSizeBinary(a) => {
483                for byte in a.value(self.idx) {
484                    write!(f, "{:02x}", byte)?;
485                }
486                Ok(())
487            }
488            ArrayOrd::List(_, offsets, nested) => {
489                write!(
490                    f,
491                    "[{}]",
492                    mz_ore::str::separated(", ", list_range(offsets, nested, self.idx))
493                )
494            }
495            ArrayOrd::Struct(_, nested) => write!(
496                f,
497                "{{{}}}",
498                mz_ore::str::separated(", ", nested.iter().map(|f| f.at(self.idx)))
499            ),
500        }
501    }
502}
503
504#[inline]
505fn list_range<'a>(
506    offsets: &OffsetBuffer<i32>,
507    values: &'a ArrayOrd,
508    idx: usize,
509) -> impl Iterator<Item = ArrayIdx<'a>> + Clone {
510    let offsets = offsets.inner();
511    let from = offsets[idx].as_usize();
512    let to = offsets[idx + 1].as_usize();
513    (from..to).map(|i| values.at(i))
514}
515
516impl<'a> ArrayIdx<'a> {
517    /// Returns the rough amount of space required for this entry in bytes.
518    /// (Not counting nulls, dictionary encoding, or other space optimizations.)
519    pub fn goodbytes(&self) -> usize {
520        match self.array {
521            ArrayOrd::Null(_) => 0,
522            ArrayOrd::Bool(_) => size_of::<bool>(),
523            ArrayOrd::Int8(_) => size_of::<i8>(),
524            ArrayOrd::Int16(_) => size_of::<i16>(),
525            ArrayOrd::Int32(_) => size_of::<i32>(),
526            ArrayOrd::Int64(_) => size_of::<i64>(),
527            ArrayOrd::UInt8(_) => size_of::<u8>(),
528            ArrayOrd::UInt16(_) => size_of::<u16>(),
529            ArrayOrd::UInt32(_) => size_of::<u32>(),
530            ArrayOrd::UInt64(_) => size_of::<u64>(),
531            ArrayOrd::Float32(_) => size_of::<f32>(),
532            ArrayOrd::Float64(_) => size_of::<f64>(),
533            ArrayOrd::String(a) => a.value(self.idx).len(),
534            ArrayOrd::Binary(a) => a.value(self.idx).len(),
535            ArrayOrd::FixedSizeBinary(a) => a.value_length().as_usize(),
536            ArrayOrd::List(_, offsets, nested) => {
537                // Range over the list, summing up the bytes for each entry.
538                list_range(offsets, nested, self.idx)
539                    .map(|a| a.goodbytes())
540                    .sum()
541            }
542            ArrayOrd::Struct(_, nested) => nested.iter().map(|a| a.at(self.idx).goodbytes()).sum(),
543        }
544    }
545}
546
547impl<'a> Ord for ArrayIdx<'a> {
548    fn cmp(&self, other: &Self) -> Ordering {
549        #[inline]
550        fn is_null(buffer: &Option<NullBuffer>, idx: usize) -> bool {
551            buffer.as_ref().map_or(false, |b| b.is_null(idx))
552        }
553        #[inline]
554        fn cmp<A: ArrayAccessor>(
555            left: A,
556            left_idx: usize,
557            right: A,
558            right_idx: usize,
559            cmp: fn(&A::Item, &A::Item) -> Ordering,
560        ) -> Ordering {
561            // NB: nulls sort last, conveniently matching psql / mz_repr
562            match (left.is_null(left_idx), right.is_null(right_idx)) {
563                (false, true) => Ordering::Less,
564                (true, true) => Ordering::Equal,
565                (true, false) => Ordering::Greater,
566                (false, false) => cmp(&left.value(left_idx), &right.value(right_idx)),
567            }
568        }
569        match (&self.array, &other.array) {
570            (ArrayOrd::Null(s), ArrayOrd::Null(o)) => {
571                debug_assert!(
572                    self.idx < s.len() && other.idx < o.len(),
573                    "null array indices in bounds"
574                );
575                Ordering::Equal
576            }
577            // For arrays with "simple" value types, we fetch and compare the underlying values directly.
578            (ArrayOrd::Bool(s), ArrayOrd::Bool(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
579            (ArrayOrd::Int8(s), ArrayOrd::Int8(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
580            (ArrayOrd::Int16(s), ArrayOrd::Int16(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
581            (ArrayOrd::Int32(s), ArrayOrd::Int32(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
582            (ArrayOrd::Int64(s), ArrayOrd::Int64(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
583            (ArrayOrd::UInt8(s), ArrayOrd::UInt8(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
584            (ArrayOrd::UInt16(s), ArrayOrd::UInt16(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
585            (ArrayOrd::UInt32(s), ArrayOrd::UInt32(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
586            (ArrayOrd::UInt64(s), ArrayOrd::UInt64(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
587            (ArrayOrd::Float32(s), ArrayOrd::Float32(o)) => {
588                cmp(s, self.idx, o, other.idx, f32::total_cmp)
589            }
590            (ArrayOrd::Float64(s), ArrayOrd::Float64(o)) => {
591                cmp(s, self.idx, o, other.idx, f64::total_cmp)
592            }
593            (ArrayOrd::String(s), ArrayOrd::String(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
594            (ArrayOrd::Binary(s), ArrayOrd::Binary(o)) => cmp(s, self.idx, o, other.idx, Ord::cmp),
595            (ArrayOrd::FixedSizeBinary(s), ArrayOrd::FixedSizeBinary(o)) => {
596                cmp(s, self.idx, o, other.idx, Ord::cmp)
597            }
598            // For lists, we generate an iterator for each side that ranges over the correct
599            // indices into the value buffer, then compare them lexicographically.
600            (
601                ArrayOrd::List(s_nulls, s_offset, s_values),
602                ArrayOrd::List(o_nulls, o_offset, o_values),
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) => list_range(s_offset, s_values, self.idx)
608                    .cmp(list_range(o_offset, o_values, other.idx)),
609            },
610            // For structs, we iterate over the same index in each field for each input,
611            // comparing them lexicographically in order.
612            (ArrayOrd::Struct(s_nulls, s_cols), ArrayOrd::Struct(o_nulls, o_cols)) => {
613                match (is_null(s_nulls, self.idx), is_null(o_nulls, other.idx)) {
614                    (false, true) => Ordering::Less,
615                    (true, true) => Ordering::Equal,
616                    (true, false) => Ordering::Greater,
617                    (false, false) => {
618                        let s = s_cols.iter().map(|array| array.at(self.idx));
619                        let o = o_cols.iter().map(|array| array.at(other.idx));
620                        s.cmp(o)
621                    }
622                }
623            }
624            (_, _) => panic!("array types did not match"),
625        }
626    }
627}
628
629impl<'a> PartialOrd for ArrayIdx<'a> {
630    fn partial_cmp(&self, other: &ArrayIdx) -> Option<Ordering> {
631        Some(self.cmp(other))
632    }
633}
634
635impl<'a> PartialEq for ArrayIdx<'a> {
636    fn eq(&self, other: &ArrayIdx) -> bool {
637        self.cmp(other) == Ordering::Equal
638    }
639}
640
641impl<'a> Eq for ArrayIdx<'a> {}
642
643/// An array with precisely one entry, for use as a lower bound.
644#[derive(Debug, Clone)]
645pub struct ArrayBound {
646    raw: ArrayRef,
647    ord: ArrayOrd,
648    index: usize,
649}
650
651impl PartialEq for ArrayBound {
652    fn eq(&self, other: &Self) -> bool {
653        self.get().eq(&other.get())
654    }
655}
656
657impl Eq for ArrayBound {}
658
659impl ArrayBound {
660    /// Create a new `ArrayBound` for this array, with the bound at the provided index.
661    pub fn new(array: ArrayRef, index: usize) -> Self {
662        Self {
663            ord: ArrayOrd::new(array.as_ref()),
664            raw: array,
665            index,
666        }
667    }
668
669    /// Get the value of the bound.
670    pub fn get(&self) -> ArrayIdx<'_> {
671        self.ord.at(self.index)
672    }
673
674    /// Convert to an array-data proto, respecting a maximum data size. The resulting proto will
675    /// decode to a single-row array, such that `ArrayBound::new(decoded, 0).get() <= self.get()`,
676    /// which makes it suitable as a lower bound.
677    pub fn to_proto_lower(&self, max_len: usize) -> Option<ProtoArrayData> {
678        // Use `take` instead of slice to make sure we encode just the relevant row to proto,
679        // instead of some larger buffer with an offset.
680        let indices = UInt64Array::from_value(u64::usize_as(self.index), 1);
681        let taken = arrow::compute::take(self.raw.as_ref(), &indices, None).ok()?;
682        let array_data = taken.into_data();
683
684        let mut proto = array_data.into_proto();
685        let original_len = proto.encoded_len();
686        if original_len <= max_len {
687            return Some(proto);
688        }
689
690        let mut data_type = proto.data_type.take()?;
691        maybe_trim_proto(&mut data_type, &mut proto, max_len);
692        proto.data_type = Some(data_type);
693
694        if cfg!(debug_assertions) {
695            let array: ArrayData = proto
696                .clone()
697                .into_rust()
698                .expect("trimmed array data can still be decoded");
699            assert_eq!(array.len(), 1);
700            let new_bound = Self::new(make_array(array), 0);
701            assert!(
702                new_bound.get() <= self.get(),
703                "trimmed bound should be comparable to and no larger than the original data"
704            )
705        }
706
707        if proto.encoded_len() <= max_len {
708            Some(proto)
709        } else {
710            None
711        }
712    }
713}
714
715/// Makes a best effort to shrink the proto while preserving the ordering.
716/// (The proto might not be smaller after this method is called, but it should always
717/// be a valid lower bound.)
718///
719/// Note that we pass in the data type and the array data separately, since we only keep
720/// type info at the top level. If a caller does have a top-level `ArrayData` instance,
721/// they should take that type and pass it in separately.
722fn maybe_trim_proto(data_type: &mut proto::DataType, body: &mut ProtoArrayData, max_len: usize) {
723    assert!(body.data_type.is_none(), "expected separate data type");
724    // TODO: consider adding cases for strings and byte arrays
725    let encoded_len = data_type.encoded_len() + body.encoded_len();
726    match &mut data_type.kind {
727        Some(data_type::Kind::Struct(data_type::Struct { children: fields })) => {
728            // Pop off fields one by one, keeping an estimate of the encoded length.
729            let mut struct_len = encoded_len;
730            while struct_len > max_len {
731                let Some(mut child) = body.children.pop() else {
732                    break;
733                };
734                let Some(mut field) = fields.pop() else { break };
735
736                struct_len -= field.encoded_len() + child.encoded_len();
737                if let Some(remaining_len) = max_len.checked_sub(struct_len) {
738                    // We're under budget after removing this field! See if we can
739                    // shrink it to fit, but exit the loop regardless.
740                    let Some(field_type) = field.data_type.as_mut() else {
741                        break;
742                    };
743                    maybe_trim_proto(field_type, &mut child, remaining_len);
744                    if field.encoded_len() + child.encoded_len() <= remaining_len {
745                        fields.push(field);
746                        body.children.push(child);
747                    }
748                    break;
749                }
750            }
751        }
752        _ => {}
753    };
754}
755
756#[cfg(test)]
757mod tests {
758    use crate::arrow::{ArrayBound, ArrayOrd};
759    use arrow::array::{
760        ArrayRef, AsArray, BooleanArray, StringArray, StructArray, UInt64Array, make_array,
761    };
762    use arrow::datatypes::{DataType, Field, Fields};
763    use mz_ore::assert_none;
764    use mz_proto::ProtoType;
765    use std::sync::Arc;
766
767    #[mz_ore::test]
768    fn trim_proto() {
769        let nested_fields: Fields = vec![Field::new("a", DataType::UInt64, true)].into();
770        let array: ArrayRef = Arc::new(StructArray::new(
771            vec![
772                Field::new("a", DataType::UInt64, true),
773                Field::new("b", DataType::Utf8, true),
774                Field::new_struct("c", nested_fields.clone(), true),
775            ]
776            .into(),
777            vec![
778                Arc::new(UInt64Array::from_iter_values([1])),
779                Arc::new(StringArray::from_iter_values(["large".repeat(50)])),
780                Arc::new(StructArray::new_null(nested_fields, 1)),
781            ],
782            None,
783        ));
784        let bound = ArrayBound::new(array, 0);
785
786        assert_none!(bound.to_proto_lower(0));
787        assert_none!(bound.to_proto_lower(1));
788
789        let proto = bound
790            .to_proto_lower(100)
791            .expect("can fit something in less than 100 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"],
796            "only the first column should fit"
797        );
798
799        let proto = bound
800            .to_proto_lower(1000)
801            .expect("can fit everything in less than 1000 bytes");
802        let array = make_array(proto.into_rust().expect("valid proto"));
803        assert_eq!(
804            array.as_struct().column_names().as_slice(),
805            &["a", "b", "c"],
806            "all columns should fit"
807        )
808    }
809
810    #[mz_ore::test]
811    fn struct_ord() {
812        let prefix = StructArray::new(
813            vec![Field::new("a", DataType::UInt64, true)].into(),
814            vec![Arc::new(UInt64Array::from_iter_values([1, 3, 5]))],
815            None,
816        );
817        let full = StructArray::new(
818            vec![
819                Field::new("a", DataType::UInt64, true),
820                Field::new("b", DataType::Utf8, true),
821            ]
822            .into(),
823            vec![
824                Arc::new(UInt64Array::from_iter_values([2, 3, 4])),
825                Arc::new(StringArray::from_iter_values(["a", "b", "c"])),
826            ],
827            None,
828        );
829        let prefix_ord = ArrayOrd::new(&prefix);
830        let full_ord = ArrayOrd::new(&full);
831
832        // Comparison works as normal over the shared columns... but when those columns are identical,
833        // the shorter struct is always smaller.
834        assert!(prefix_ord.at(0) < full_ord.at(0), "(1) < (2, 'a')");
835        assert!(prefix_ord.at(1) < full_ord.at(1), "(3) < (3, 'b')");
836        assert!(prefix_ord.at(2) > full_ord.at(2), "(5) < (4, 'c')");
837    }
838
839    #[mz_ore::test]
840    #[should_panic(expected = "array types did not match")]
841    fn struct_ord_incompat() {
842        // This test is descriptive, not prescriptive: we declare it is an error to compare
843        // structs like this, but not what the result of comparing them is.
844        let string = StructArray::new(
845            vec![
846                Field::new("a", DataType::UInt64, true),
847                Field::new("b", DataType::Utf8, true),
848            ]
849            .into(),
850            vec![
851                Arc::new(UInt64Array::from_iter_values([1])),
852                Arc::new(StringArray::from_iter_values(["a"])),
853            ],
854            None,
855        );
856        let boolean = StructArray::new(
857            vec![
858                Field::new("a", DataType::UInt64, true),
859                Field::new("b", DataType::Boolean, true),
860            ]
861            .into(),
862            vec![
863                Arc::new(UInt64Array::from_iter_values([1])),
864                Arc::new(BooleanArray::from_iter([Some(true)])),
865            ],
866            None,
867        );
868        let string_ord = ArrayOrd::new(&string);
869        let bool_ord = ArrayOrd::new(&boolean);
870
871        // Despite the matching first column, this will panic with a type mismatch.
872        assert!(string_ord.at(0) < bool_ord.at(0));
873    }
874}
mz_persist_types/arrow.rs

mz_persist_types/
arrow.rs
