vortex_compressor/builtins/constant/
bool.rs

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: Copyright the Vortex contributors
3
4//! Constant encoding for bool arrays.
5
6use vortex_array::ArrayRef;
7use vortex_array::Canonical;
8use vortex_array::ExecutionCtx;
9use vortex_error::VortexResult;
10
11use crate::CascadingCompressor;
12use crate::builtins::constant::compress_constant_array_with_validity;
13use crate::ctx::CompressorContext;
14use crate::estimate::CompressionEstimate;
15use crate::estimate::EstimateVerdict;
16use crate::scheme::Scheme;
17use crate::stats::ArrayAndStats;
18
19/// Constant encoding for bool arrays where all valid values are the same.
20#[derive(Debug, Copy, Clone, PartialEq, Eq)]
21pub struct BoolConstantScheme;
22
23impl Scheme for BoolConstantScheme {
24    fn scheme_name(&self) -> &'static str {
25        "vortex.bool.constant"
26    }
27
28    fn matches(&self, canonical: &Canonical) -> bool {
29        matches!(canonical, Canonical::Bool(_))
30    }
31
32    fn expected_compression_ratio(
33        &self,
34        data: &ArrayAndStats,
35        compress_ctx: CompressorContext,
36        exec_ctx: &mut ExecutionCtx,
37    ) -> CompressionEstimate {
38        // Constant detection on a sample is a false positive, since the sample being constant does
39        // not mean the full array is constant.
40        if compress_ctx.is_sample() {
41            return CompressionEstimate::Verdict(EstimateVerdict::Skip);
42        }
43
44        let array_len = data.array().len();
45        let stats = data.bool_stats(exec_ctx);
46
47        // We want to use `Constant` if there are only nulls in the array.
48        if stats.value_count() == 0 {
49            debug_assert_eq!(stats.null_count() as usize, array_len);
50            return CompressionEstimate::Verdict(EstimateVerdict::AlwaysUse);
51        }
52
53        if stats.is_constant() {
54            return CompressionEstimate::Verdict(EstimateVerdict::AlwaysUse);
55        }
56
57        CompressionEstimate::Verdict(EstimateVerdict::Skip)
58    }
59
60    fn compress(
61        &self,
62        _compressor: &CascadingCompressor,
63        data: &ArrayAndStats,
64        _compress_ctx: CompressorContext,
65        exec_ctx: &mut ExecutionCtx,
66    ) -> VortexResult<ArrayRef> {
67        compress_constant_array_with_validity(data.array(), exec_ctx)
68    }
69}
vortex_compressor/builtins/constant/bool.rs

vortex_compressor/builtins/constant/
bool.rs
