vortex_fsst/compute/
compare.rs

1use vortex_array::arrays::{BoolArray, BooleanBuffer, ConstantArray};
2use vortex_array::compute::{
3    CompareKernel, CompareKernelAdapter, Operator, compare, compare_lengths_to_empty,
4};
5use vortex_array::validity::Validity;
6use vortex_array::{Array, ArrayRef, IntoArray, ToCanonical, register_kernel};
7use vortex_buffer::ByteBuffer;
8use vortex_dtype::{DType, match_each_native_ptype};
9use vortex_error::{VortexExpect, VortexResult, vortex_bail};
10use vortex_scalar::Scalar;
11
12use crate::{FSSTArray, FSSTVTable};
13
14impl CompareKernel for FSSTVTable {
15    fn compare(
16        &self,
17        lhs: &FSSTArray,
18        rhs: &dyn Array,
19        operator: Operator,
20    ) -> VortexResult<Option<ArrayRef>> {
21        match rhs.as_constant() {
22            Some(constant) => compare_fsst_constant(lhs, &constant, operator),
23            // Otherwise, fall back to the default comparison behavior.
24            _ => Ok(None),
25        }
26    }
27}
28
29register_kernel!(CompareKernelAdapter(FSSTVTable).lift());
30
31/// Specialized compare function implementation used when performing against a constant
32fn compare_fsst_constant(
33    left: &FSSTArray,
34    right: &Scalar,
35    operator: Operator,
36) -> VortexResult<Option<ArrayRef>> {
37    let is_rhs_empty = match right.dtype() {
38        DType::Binary(_) => right
39            .as_binary()
40            .is_empty()
41            .vortex_expect("RHS should not be null"),
42        DType::Utf8(_) => right
43            .as_utf8()
44            .is_empty()
45            .vortex_expect("RHS should not be null"),
46        _ => vortex_bail!("VarBinArray can only have type of Binary or Utf8"),
47    };
48    if is_rhs_empty {
49        let buffer = match operator {
50            // Every possible value is gte ""
51            Operator::Gte => BooleanBuffer::new_set(left.len()),
52            // No value is lt ""
53            Operator::Lt => BooleanBuffer::new_unset(left.len()),
54            _ => {
55                let uncompressed_lengths = left.uncompressed_lengths().to_primitive()?;
56                match_each_native_ptype!(uncompressed_lengths.ptype(), |P| {
57                    compare_lengths_to_empty(
58                        uncompressed_lengths.as_slice::<P>().iter().copied(),
59                        operator,
60                    )
61                })
62            }
63        };
64
65        return Ok(Some(
66            BoolArray::new(
67                buffer,
68                Validity::copy_from_array(left.as_ref())?
69                    .union_nullability(right.dtype().nullability()),
70            )
71            .into_array(),
72        ));
73    }
74
75    // The following section only supports Eq/NotEq
76    if !matches!(operator, Operator::Eq | Operator::NotEq) {
77        return Ok(None);
78    }
79
80    let compressor = left.compressor();
81    let encoded_buffer = match left.dtype() {
82        DType::Utf8(_) => {
83            let value = right
84                .as_utf8()
85                .value()
86                .vortex_expect("Expected non-null scalar");
87            ByteBuffer::from(compressor.compress(value.as_bytes()))
88        }
89        DType::Binary(_) => {
90            let value = right
91                .as_binary()
92                .value()
93                .vortex_expect("Expected non-null scalar");
94            ByteBuffer::from(compressor.compress(value.as_slice()))
95        }
96        _ => unreachable!("FSSTArray can only have string or binary data type"),
97    };
98
99    let encoded_scalar = Scalar::new(
100        DType::Binary(left.dtype().nullability() | right.dtype().nullability()),
101        encoded_buffer.into(),
102    );
103
104    let rhs = ConstantArray::new(encoded_scalar, left.len());
105    compare(left.codes().as_ref(), rhs.as_ref(), operator).map(Some)
106}
107
108#[cfg(test)]
109mod tests {
110    use vortex_array::arrays::{ConstantArray, VarBinArray};
111    use vortex_array::compute::{Operator, compare};
112    use vortex_array::{Array, ToCanonical};
113    use vortex_dtype::{DType, Nullability};
114    use vortex_scalar::Scalar;
115
116    use crate::{fsst_compress, fsst_train_compressor};
117
118    #[test]
119    #[cfg_attr(miri, ignore)]
120    fn test_compare_fsst() {
121        let lhs = VarBinArray::from_iter(
122            [
123                Some("hello"),
124                None,
125                Some("world"),
126                None,
127                Some("this is a very long string"),
128            ],
129            DType::Utf8(Nullability::Nullable),
130        );
131        let compressor = fsst_train_compressor(lhs.as_ref()).unwrap();
132        let lhs = fsst_compress(lhs.as_ref(), &compressor).unwrap();
133
134        let rhs = ConstantArray::new("world", lhs.len());
135
136        // Ensure fastpath for Eq exists, and returns correct answer
137        let equals = compare(lhs.as_ref(), rhs.as_ref(), Operator::Eq)
138            .unwrap()
139            .to_bool()
140            .unwrap();
141
142        assert_eq!(equals.dtype(), &DType::Bool(Nullability::Nullable));
143
144        assert_eq!(
145            equals.boolean_buffer().into_iter().collect::<Vec<_>>(),
146            vec![false, false, true, false, false]
147        );
148
149        // Ensure fastpath for Eq exists, and returns correct answer
150        let not_equals = compare(lhs.as_ref(), rhs.as_ref(), Operator::NotEq)
151            .unwrap()
152            .to_bool()
153            .unwrap();
154
155        assert_eq!(not_equals.dtype(), &DType::Bool(Nullability::Nullable));
156        assert_eq!(
157            not_equals.boolean_buffer().into_iter().collect::<Vec<_>>(),
158            vec![true, true, false, true, true]
159        );
160
161        // Ensure null constants are handled correctly.
162        let null_rhs =
163            ConstantArray::new(Scalar::null(DType::Utf8(Nullability::Nullable)), lhs.len());
164        let equals_null = compare(lhs.as_ref(), null_rhs.as_ref(), Operator::Eq).unwrap();
165        for idx in 0..lhs.len() {
166            assert!(equals_null.scalar_at(idx).unwrap().is_null());
167        }
168
169        let noteq_null = compare(lhs.as_ref(), null_rhs.as_ref(), Operator::NotEq).unwrap();
170        for idx in 0..lhs.len() {
171            assert!(noteq_null.scalar_at(idx).unwrap().is_null());
172        }
173    }
174}
vortex_fsst/compute/compare.rs

vortex_fsst/compute/
compare.rs
