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) => {
23                compare_fsst_constant(lhs, &ConstantArray::new(constant, lhs.len()), operator)
24            }
25            // Otherwise, fall back to the default comparison behavior.
26            _ => Ok(None),
27        }
28    }
29}
30
31register_kernel!(CompareKernelAdapter(FSSTVTable).lift());
32
33/// Specialized compare function implementation used when performing against a constant
34fn compare_fsst_constant(
35    left: &FSSTArray,
36    right: &ConstantArray,
37    operator: Operator,
38) -> VortexResult<Option<ArrayRef>> {
39    let rhs_scalar = right.scalar();
40    let is_rhs_empty = match rhs_scalar.dtype() {
41        DType::Binary(_) => rhs_scalar
42            .as_binary()
43            .is_empty()
44            .vortex_expect("RHS should not be null"),
45        DType::Utf8(_) => rhs_scalar
46            .as_utf8()
47            .is_empty()
48            .vortex_expect("RHS should not be null"),
49        _ => vortex_bail!("VarBinArray can only have type of Binary or Utf8"),
50    };
51    if is_rhs_empty {
52        let buffer = match operator {
53            // Every possible value is gte ""
54            Operator::Gte => BooleanBuffer::new_set(left.len()),
55            // No value is lt ""
56            Operator::Lt => BooleanBuffer::new_unset(left.len()),
57            _ => {
58                let uncompressed_lengths = left.uncompressed_lengths().to_primitive()?;
59                match_each_native_ptype!(uncompressed_lengths.ptype(), |$P| {
60                    compare_lengths_to_empty(uncompressed_lengths.as_slice::<$P>().iter().copied(), operator)
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 = fsst::Compressor::rebuild_from(left.symbols(), left.symbol_lengths());
81
82    let encoded_buffer = match left.dtype() {
83        DType::Utf8(_) => {
84            let value = right
85                .scalar()
86                .as_utf8()
87                .value()
88                .vortex_expect("Expected non-null scalar");
89            ByteBuffer::from(compressor.compress(value.as_bytes()))
90        }
91        DType::Binary(_) => {
92            let value = right
93                .scalar()
94                .as_binary()
95                .value()
96                .vortex_expect("Expected non-null scalar");
97            ByteBuffer::from(compressor.compress(value.as_slice()))
98        }
99        _ => unreachable!("FSSTArray can only have string or binary data type"),
100    };
101
102    let encoded_scalar = Scalar::new(
103        DType::Binary(left.dtype().nullability() | right.dtype().nullability()),
104        encoded_buffer.into(),
105    );
106
107    let rhs = ConstantArray::new(encoded_scalar, left.len());
108    compare(left.codes().as_ref(), rhs.as_ref(), operator).map(Some)
109}
110
111#[cfg(test)]
112mod tests {
113    use vortex_array::arrays::{ConstantArray, VarBinArray};
114    use vortex_array::compute::{Operator, compare};
115    use vortex_array::{Array, ToCanonical};
116    use vortex_dtype::{DType, Nullability};
117    use vortex_scalar::Scalar;
118
119    use crate::{fsst_compress, fsst_train_compressor};
120
121    #[test]
122    #[cfg_attr(miri, ignore)]
123    fn test_compare_fsst() {
124        let lhs = VarBinArray::from_iter(
125            [
126                Some("hello"),
127                None,
128                Some("world"),
129                None,
130                Some("this is a very long string"),
131            ],
132            DType::Utf8(Nullability::Nullable),
133        );
134        let compressor = fsst_train_compressor(lhs.as_ref()).unwrap();
135        let lhs = fsst_compress(lhs.as_ref(), &compressor).unwrap();
136
137        let rhs = ConstantArray::new("world", lhs.len());
138
139        // Ensure fastpath for Eq exists, and returns correct answer
140        let equals = compare(lhs.as_ref(), rhs.as_ref(), Operator::Eq)
141            .unwrap()
142            .to_bool()
143            .unwrap();
144
145        assert_eq!(equals.dtype(), &DType::Bool(Nullability::Nullable));
146
147        assert_eq!(
148            equals.boolean_buffer().into_iter().collect::<Vec<_>>(),
149            vec![false, false, true, false, false]
150        );
151
152        // Ensure fastpath for Eq exists, and returns correct answer
153        let not_equals = compare(lhs.as_ref(), rhs.as_ref(), Operator::NotEq)
154            .unwrap()
155            .to_bool()
156            .unwrap();
157
158        assert_eq!(not_equals.dtype(), &DType::Bool(Nullability::Nullable));
159        assert_eq!(
160            not_equals.boolean_buffer().into_iter().collect::<Vec<_>>(),
161            vec![true, true, false, true, true]
162        );
163
164        // Ensure null constants are handled correctly.
165        let null_rhs =
166            ConstantArray::new(Scalar::null(DType::Utf8(Nullability::Nullable)), lhs.len());
167        let equals_null = compare(lhs.as_ref(), null_rhs.as_ref(), Operator::Eq).unwrap();
168        for idx in 0..lhs.len() {
169            assert!(equals_null.scalar_at(idx).unwrap().is_null());
170        }
171
172        let noteq_null = compare(lhs.as_ref(), null_rhs.as_ref(), Operator::NotEq).unwrap();
173        for idx in 0..lhs.len() {
174            assert!(noteq_null.scalar_at(idx).unwrap().is_null());
175        }
176    }
177}
vortex_fsst/compute/compare.rs

vortex_fsst/compute/
compare.rs
