vortex_btrblocks/schemes/
temporal.rs

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: Copyright the Vortex contributors
3
4//! Temporal compression scheme using datetime-part decomposition.
5
6use vortex_array::ArrayRef;
7use vortex_array::Canonical;
8use vortex_array::IntoArray;
9use vortex_array::LEGACY_SESSION;
10use vortex_array::ToCanonical;
11use vortex_array::VortexSessionExecute;
12use vortex_array::aggregate_fn::fns::is_constant::is_constant;
13use vortex_array::arrays::ConstantArray;
14use vortex_array::arrays::TemporalArray;
15use vortex_array::arrays::primitive::PrimitiveArrayExt;
16use vortex_array::dtype::extension::Matcher;
17use vortex_array::extension::datetime::AnyTemporal;
18use vortex_array::extension::datetime::TemporalMetadata;
19use vortex_compressor::estimate::CompressionEstimate;
20use vortex_compressor::estimate::EstimateVerdict;
21use vortex_datetime_parts::DateTimeParts;
22use vortex_datetime_parts::TemporalParts;
23use vortex_datetime_parts::split_temporal;
24use vortex_error::VortexResult;
25
26use crate::ArrayAndStats;
27use crate::CascadingCompressor;
28use crate::CompressorContext;
29use crate::Scheme;
30use crate::SchemeExt;
31
32/// Compression scheme for temporal timestamp arrays via datetime-part decomposition.
33///
34/// Splits timestamps into days, seconds, and subseconds components, compresses each
35/// independently, and wraps the result in a `DateTimePartsArray`.
36#[derive(Debug, Copy, Clone, PartialEq, Eq)]
37pub struct TemporalScheme;
38
39impl Scheme for TemporalScheme {
40    fn scheme_name(&self) -> &'static str {
41        "vortex.ext.temporal"
42    }
43
44    fn matches(&self, canonical: &Canonical) -> bool {
45        let Canonical::Extension(ext) = canonical else {
46            return false;
47        };
48
49        let ext_dtype = ext.ext_dtype();
50
51        matches!(
52            AnyTemporal::try_match(ext_dtype),
53            Some(TemporalMetadata::Timestamp(..))
54        )
55    }
56
57    /// Children: days=0, seconds=1, subseconds=2.
58    fn num_children(&self) -> usize {
59        3
60    }
61
62    fn expected_compression_ratio(
63        &self,
64        _data: &mut ArrayAndStats,
65        _ctx: CompressorContext,
66    ) -> CompressionEstimate {
67        // Temporal compression (splitting into parts) is almost always beneficial.
68        CompressionEstimate::Verdict(EstimateVerdict::AlwaysUse)
69    }
70
71    fn compress(
72        &self,
73        compressor: &CascadingCompressor,
74        data: &mut ArrayAndStats,
75        ctx: CompressorContext,
76    ) -> VortexResult<ArrayRef> {
77        let array = data.array().clone();
78        let ext_array = array.to_extension();
79        let temporal_array = TemporalArray::try_from(ext_array.clone().into_array())?;
80
81        // Check for constant array and return early if so.
82        let is_constant = is_constant(
83            &ext_array.clone().into_array(),
84            &mut compressor.execution_ctx(),
85        )?;
86
87        if is_constant {
88            return Ok(ConstantArray::new(
89                ext_array.execute_scalar(0, &mut LEGACY_SESSION.create_execution_ctx())?,
90                ext_array.len(),
91            )
92            .into_array());
93        }
94
95        let dtype = temporal_array.dtype().clone();
96        let TemporalParts {
97            days,
98            seconds,
99            subseconds,
100        } = split_temporal(temporal_array)?;
101
102        let days = compressor.compress_child(
103            &days.to_primitive().narrow()?.into_array(),
104            &ctx,
105            self.id(),
106            0,
107        )?;
108        let seconds = compressor.compress_child(
109            &seconds.to_primitive().narrow()?.into_array(),
110            &ctx,
111            self.id(),
112            1,
113        )?;
114        let subseconds = compressor.compress_child(
115            &subseconds.to_primitive().narrow()?.into_array(),
116            &ctx,
117            self.id(),
118            2,
119        )?;
120
121        Ok(DateTimeParts::try_new(dtype, days, seconds, subseconds)?.into_array())
122    }
123}
vortex_btrblocks/schemes/temporal.rs

vortex_btrblocks/schemes/
temporal.rs
