mz_timely_util/
columnar.rs

1// Copyright Materialize, Inc. and contributors. All rights reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License in the LICENSE file at the
6// root of this repository, or online at
7//
8//     http://www.apache.org/licenses/LICENSE-2.0
9//
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15
16//! Container for columnar data.
17
18#![deny(missing_docs)]
19
20pub mod batcher;
21pub mod builder;
22
23use std::hash::Hash;
24
25use columnar::Container as _;
26use columnar::bytes::{EncodeDecode, Indexed};
27use columnar::common::IterOwn;
28use columnar::{Columnar, Ref};
29use columnar::{FromBytes, Index, Len};
30use differential_dataflow::Hashable;
31use differential_dataflow::containers::TimelyStack;
32use differential_dataflow::trace::implementations::merge_batcher::{ColMerger, MergeBatcher};
33use mz_ore::region::Region;
34use timely::Accountable;
35use timely::bytes::arc::Bytes;
36use timely::container::{DrainContainer, IterContainer, PushInto};
37use timely::dataflow::channels::ContainerBytes;
38
39/// A batcher for columnar storage.
40pub type Col2ValBatcher<K, V, T, R> = MergeBatcher<
41    Column<((K, V), T, R)>,
42    batcher::Chunker<TimelyStack<((K, V), T, R)>>,
43    ColMerger<(K, V), T, R>,
44>;
45/// A batcher for columnar storage with unit values.
46pub type Col2KeyBatcher<K, T, R> = Col2ValBatcher<K, (), T, R>;
47
48/// A container based on a columnar store, encoded in aligned bytes.
49///
50/// The type can represent typed data, bytes from Timely, or an aligned allocation. The name
51/// is singular to express that the preferred format is [`Column::Align`]. The [`Column::Typed`]
52/// variant is used to construct the container, and it owns potentially multiple columns of data.
53pub enum Column<C: Columnar> {
54    /// The typed variant of the container.
55    Typed(C::Container),
56    /// The binary variant of the container.
57    Bytes(Bytes),
58    /// Relocated, aligned binary data, if `Bytes` doesn't work for some reason.
59    ///
60    /// Reasons could include misalignment, cloning of data, or wanting
61    /// to release the `Bytes` as a scarce resource.
62    Align(Region<u64>),
63}
64
65impl<C: Columnar> Column<C> {
66    /// Borrows the container as a reference.
67    #[inline]
68    pub fn borrow(&self) -> <C::Container as columnar::Container>::Borrowed<'_> {
69        match self {
70            Column::Typed(t) => t.borrow(),
71            Column::Bytes(b) => <<C::Container as columnar::Container>::Borrowed<'_>>::from_bytes(
72                &mut Indexed::decode(bytemuck::cast_slice(b)),
73            ),
74            Column::Align(a) => <<C::Container as columnar::Container>::Borrowed<'_>>::from_bytes(
75                &mut Indexed::decode(a),
76            ),
77        }
78    }
79}
80
81impl<C: Columnar> Default for Column<C> {
82    fn default() -> Self {
83        Self::Typed(Default::default())
84    }
85}
86
87impl<C: Columnar> Clone for Column<C>
88where
89    C::Container: Clone,
90{
91    fn clone(&self) -> Self {
92        match self {
93            // Typed stays typed, although we would have the option to move to aligned data.
94            // If we did it might be confusing why we couldn't push into a cloned column.
95            Column::Typed(t) => Column::Typed(t.clone()),
96            Column::Bytes(b) => {
97                assert_eq!(b.len() % 8, 0);
98                let mut alloc: Region<u64> = crate::containers::alloc_aligned_zeroed(b.len() / 8);
99                let alloc_bytes = bytemuck::cast_slice_mut(&mut alloc);
100                alloc_bytes[..b.len()].copy_from_slice(b);
101                Self::Align(alloc)
102            }
103            Column::Align(a) => {
104                let mut alloc = crate::containers::alloc_aligned_zeroed(a.len());
105                alloc[..a.len()].copy_from_slice(a);
106                Column::Align(alloc)
107            }
108        }
109    }
110}
111
112impl<C: Columnar> Accountable for Column<C> {
113    #[inline]
114    fn record_count(&self) -> i64 {
115        self.borrow().len().try_into().expect("Must fit")
116    }
117}
118impl<C: Columnar> DrainContainer for Column<C> {
119    type Item<'a> = columnar::Ref<'a, C>;
120    type DrainIter<'a> = IterOwn<<C::Container as columnar::Container>::Borrowed<'a>>;
121    #[inline]
122    fn drain(&mut self) -> Self::DrainIter<'_> {
123        self.borrow().into_index_iter()
124    }
125}
126impl<C: Columnar> IterContainer for Column<C> {
127    type ItemRef<'a> = columnar::Ref<'a, C>;
128    type Iter<'a> = IterOwn<<C::Container as columnar::Container>::Borrowed<'a>>;
129    #[inline]
130    fn iter(&self) -> Self::Iter<'_> {
131        self.borrow().into_index_iter()
132    }
133}
134
135impl<C: Columnar, T> PushInto<T> for Column<C>
136where
137    C::Container: columnar::Push<T>,
138{
139    #[inline]
140    fn push_into(&mut self, item: T) {
141        use columnar::Push;
142        match self {
143            Column::Typed(t) => t.push(item),
144            Column::Align(_) | Column::Bytes(_) => {
145                // We really oughtn't be calling this in this case.
146                // We could convert to owned, but need more constraints on `C`.
147                unimplemented!("Pushing into Column::Bytes without first clearing");
148            }
149        }
150    }
151}
152
153impl<C: Columnar> ContainerBytes for Column<C> {
154    #[inline]
155    fn from_bytes(bytes: Bytes) -> Self {
156        // Our expectation / hope is that `bytes` is `u64` aligned and sized.
157        // If the alignment is borked, we can relocate. If the size is borked,
158        // not sure what we do in that case. An incorrect size indicates a problem
159        // of `into_bytes`, or a failure of the communication layer, both of which
160        // are unrecoverable.
161        assert_eq!(bytes.len() % 8, 0);
162        if let Ok(_) = bytemuck::try_cast_slice::<_, u64>(&bytes) {
163            Self::Bytes(bytes)
164        } else {
165            // We failed to cast the slice, so we'll reallocate.
166            let mut alloc: Region<u64> = crate::containers::alloc_aligned_zeroed(bytes.len() / 8);
167            let alloc_bytes = bytemuck::cast_slice_mut(&mut alloc);
168            alloc_bytes[..bytes.len()].copy_from_slice(&bytes);
169            Self::Align(alloc)
170        }
171    }
172
173    #[inline]
174    fn length_in_bytes(&self) -> usize {
175        match self {
176            Column::Typed(t) => Indexed::length_in_bytes(&t.borrow()),
177            Column::Bytes(b) => b.len(),
178            Column::Align(a) => 8 * a.len(),
179        }
180    }
181
182    #[inline]
183    fn into_bytes<W: ::std::io::Write>(&self, writer: &mut W) {
184        match self {
185            Column::Typed(t) => Indexed::write(writer, &t.borrow()).unwrap(),
186            Column::Bytes(b) => writer.write_all(b).unwrap(),
187            Column::Align(a) => writer.write_all(bytemuck::cast_slice(a)).unwrap(),
188        }
189    }
190}
191
192/// An exchange function for columnar tuples of the form `((K, V), T, D)`. Rust has a hard
193/// time to figure out the lifetimes of the elements when specified as a closure, so we rather
194/// specify it as a function.
195#[inline(always)]
196pub fn columnar_exchange<K, V, T, D>(((k, _), _, _): &Ref<'_, ((K, V), T, D)>) -> u64
197where
198    K: Columnar,
199    for<'a> Ref<'a, K>: Hash,
200    V: Columnar,
201    D: Columnar,
202    T: Columnar,
203{
204    k.hashed()
205}
206
207#[cfg(test)]
208mod tests {
209    use mz_ore::region::Region;
210    use timely::bytes::arc::BytesMut;
211    use timely::container::PushInto;
212    use timely::dataflow::channels::ContainerBytes;
213
214    use super::*;
215
216    /// Produce some bytes that are in columnar format.
217    fn raw_columnar_bytes() -> Vec<u8> {
218        let mut raw = Vec::new();
219        raw.extend(16_u64.to_le_bytes()); // offsets
220        raw.extend(28_u64.to_le_bytes()); // length
221        raw.extend(1_i32.to_le_bytes());
222        raw.extend(2_i32.to_le_bytes());
223        raw.extend(3_i32.to_le_bytes());
224        raw.extend([0, 0, 0, 0]); // padding
225        raw
226    }
227
228    #[mz_ore::test]
229    fn test_column_clone() {
230        let columns = Columnar::as_columns([1, 2, 3].iter());
231        let column_typed: Column<i32> = Column::Typed(columns);
232        let column_typed2 = column_typed.clone();
233
234        assert_eq!(column_typed2.iter().collect::<Vec<_>>(), vec![&1, &2, &3]);
235
236        let bytes = BytesMut::from(raw_columnar_bytes()).freeze();
237        let column_bytes: Column<i32> = Column::Bytes(bytes);
238        let column_bytes2 = column_bytes.clone();
239
240        assert_eq!(column_bytes2.iter().collect::<Vec<_>>(), vec![&1, &2, &3]);
241
242        let raw = raw_columnar_bytes();
243        let mut region: Region<u64> = crate::containers::alloc_aligned_zeroed(raw.len() / 8);
244        let region_bytes = bytemuck::cast_slice_mut(&mut region);
245        region_bytes[..raw.len()].copy_from_slice(&raw);
246        let column_align: Column<i32> = Column::Align(region);
247        let column_align2 = column_align.clone();
248
249        assert_eq!(column_align2.iter().collect::<Vec<_>>(), vec![&1, &2, &3]);
250    }
251
252    /// Assert the desired contents of raw_columnar_bytes so that diagnosing test failures is
253    /// easier.
254    #[mz_ore::test]
255    fn test_column_known_bytes() {
256        let mut column: Column<i32> = Default::default();
257        column.push_into(1);
258        column.push_into(2);
259        column.push_into(3);
260        let mut data = Vec::new();
261        column.into_bytes(&mut std::io::Cursor::new(&mut data));
262        assert_eq!(data, raw_columnar_bytes());
263    }
264
265    #[mz_ore::test]
266    fn test_column_from_bytes() {
267        let raw = raw_columnar_bytes();
268
269        let buf = vec![0; raw.len() + 8];
270        let align = buf.as_ptr().align_offset(std::mem::size_of::<u64>());
271        let mut bytes_mut = BytesMut::from(buf);
272        let _ = bytes_mut.extract_to(align);
273        bytes_mut[..raw.len()].copy_from_slice(&raw);
274        let aligned_bytes = bytes_mut.extract_to(raw.len());
275
276        let column: Column<i32> = Column::from_bytes(aligned_bytes);
277        assert!(matches!(column, Column::Bytes(_)));
278        assert_eq!(column.iter().collect::<Vec<_>>(), vec![&1, &2, &3]);
279
280        let buf = vec![0; raw.len() + 8];
281        let align = buf.as_ptr().align_offset(std::mem::size_of::<u64>());
282        let mut bytes_mut = BytesMut::from(buf);
283        let _ = bytes_mut.extract_to(align + 1);
284        bytes_mut[..raw.len()].copy_from_slice(&raw);
285        let unaligned_bytes = bytes_mut.extract_to(raw.len());
286
287        let column: Column<i32> = Column::from_bytes(unaligned_bytes);
288        assert!(matches!(column, Column::Align(_)));
289        assert_eq!(column.iter().collect::<Vec<_>>(), vec![&1, &2, &3]);
290    }
291}
mz_timely_util/columnar.rs

mz_timely_util/
columnar.rs
