risingwave_frontend/optimizer/plan_expr_visitor/
strong.rs

1// Copyright 2025 RisingWave Labs
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 at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use fixedbitset::FixedBitSet;
16
17use crate::expr::{ExprImpl, ExprType, FunctionCall, InputRef};
18
19/// This utilities are with the same definition in calcite.
20/// Utilities for strong predicates.
21/// A predicate is strong (or null-rejecting) with regards to selected subset of inputs
22/// if it is UNKNOWN if all inputs in selected subset are UNKNOWN.
23/// By the way, UNKNOWN is just the boolean form of NULL.
24///
25/// Examples:
26///
27/// UNKNOWN is strong in `[]` (definitely null)
28///
29/// `c = 1` is strong in `[c]` (definitely null if and only if c is null)
30///
31/// `c IS NULL` is not strong (always returns TRUE or FALSE, nevernull)
32///
33/// `p1 AND p2` is strong in `[p1, p2]` (definitely null if either p1 is null or p2 is null)
34///
35/// `p1 OR p2` is strong if p1 and p2 are strong
36
37#[derive(Default)]
38pub struct Strong {
39    null_columns: FixedBitSet,
40}
41
42impl Strong {
43    fn new(null_columns: FixedBitSet) -> Self {
44        Self { null_columns }
45    }
46
47    /// Returns whether the analyzed expression will *definitely* return null if
48    /// all of a given set of input columns are null.
49    /// Note: we could not assume any null-related property for the input expression if `is_null` returns false
50    pub fn is_null(expr: &ExprImpl, null_columns: FixedBitSet) -> bool {
51        let strong = Strong::new(null_columns);
52        strong.is_null_visit(expr)
53    }
54
55    fn is_input_ref_null(&self, input_ref: &InputRef) -> bool {
56        self.null_columns.contains(input_ref.index())
57    }
58
59    fn is_null_visit(&self, expr: &ExprImpl) -> bool {
60        match expr {
61            ExprImpl::InputRef(input_ref) => self.is_input_ref_null(input_ref),
62            ExprImpl::Literal(literal) => literal.get_data().is_none(),
63            ExprImpl::FunctionCall(func_call) => self.is_null_function_call(func_call),
64            ExprImpl::FunctionCallWithLambda(_) => false,
65            ExprImpl::AggCall(_) => false,
66            ExprImpl::Subquery(_) => false,
67            ExprImpl::CorrelatedInputRef(_) => false,
68            ExprImpl::TableFunction(_) => false,
69            ExprImpl::WindowFunction(_) => false,
70            ExprImpl::UserDefinedFunction(_) => false,
71            ExprImpl::Parameter(_) => false,
72            ExprImpl::Now(_) => false,
73        }
74    }
75
76    fn is_null_function_call(&self, func_call: &FunctionCall) -> bool {
77        match func_call.func_type() {
78            // NOT NULL: This kind of expression is never null. No need to look at its arguments, if it has any.
79            ExprType::IsNull
80            | ExprType::IsNotNull
81            | ExprType::IsDistinctFrom
82            | ExprType::IsNotDistinctFrom
83            | ExprType::IsTrue
84            | ExprType::QuoteNullable
85            | ExprType::IsNotTrue
86            | ExprType::IsFalse
87            | ExprType::IsNotFalse
88            | ExprType::CheckNotNull => false,
89            // ANY: This kind of expression is null if and only if at least one of its arguments is null.
90            ExprType::Not
91            | ExprType::Equal
92            | ExprType::NotEqual
93            | ExprType::LessThan
94            | ExprType::LessThanOrEqual
95            | ExprType::GreaterThan
96            | ExprType::GreaterThanOrEqual
97            | ExprType::Like
98            | ExprType::Add
99            | ExprType::AddWithTimeZone
100            | ExprType::Subtract
101            | ExprType::Multiply
102            | ExprType::Modulus
103            | ExprType::Divide
104            | ExprType::Cast
105            | ExprType::Trim
106            | ExprType::Ltrim
107            | ExprType::Rtrim
108            | ExprType::Ceil
109            | ExprType::Floor
110            | ExprType::Extract
111            | ExprType::L2Distance
112            | ExprType::CosineDistance
113            | ExprType::L1Distance
114            | ExprType::InnerProduct
115            | ExprType::VecConcat
116            | ExprType::L2Norm
117            | ExprType::L2Normalize
118            | ExprType::Greatest
119            | ExprType::Least => self.any_null(func_call),
120            // ALL: This kind of expression is null if and only if all of its arguments are null.
121            ExprType::And | ExprType::Or | ExprType::Coalesce => self.all_null(func_call),
122            // TODO: Function like case when is important but current its structure is complicated, so we need to implement it later if necessary.
123            // Assume that any other expressions cannot be simplified.
124            ExprType::In
125            | ExprType::Some
126            | ExprType::All
127            | ExprType::BitwiseAnd
128            | ExprType::BitwiseOr
129            | ExprType::BitwiseXor
130            | ExprType::BitwiseNot
131            | ExprType::BitwiseShiftLeft
132            | ExprType::BitwiseShiftRight
133            | ExprType::DatePart
134            | ExprType::TumbleStart
135            | ExprType::MakeDate
136            | ExprType::MakeTime
137            | ExprType::MakeTimestamp
138            | ExprType::SecToTimestamptz
139            | ExprType::AtTimeZone
140            | ExprType::DateTrunc
141            | ExprType::DateBin
142            | ExprType::CharToTimestamptz
143            | ExprType::CharToDate
144            | ExprType::CastWithTimeZone
145            | ExprType::SubtractWithTimeZone
146            | ExprType::MakeTimestamptz
147            | ExprType::Substr
148            | ExprType::Length
149            | ExprType::ILike
150            | ExprType::SimilarToEscape
151            | ExprType::Upper
152            | ExprType::Lower
153            | ExprType::Replace
154            | ExprType::Position
155            | ExprType::Case
156            | ExprType::ConstantLookup
157            | ExprType::RoundDigit
158            | ExprType::Round
159            | ExprType::Ascii
160            | ExprType::Translate
161            | ExprType::Concat
162            | ExprType::ConcatVariadic
163            | ExprType::ConcatWs
164            | ExprType::ConcatWsVariadic
165            | ExprType::Abs
166            | ExprType::SplitPart
167            | ExprType::ToChar
168            | ExprType::Md5
169            | ExprType::CharLength
170            | ExprType::Repeat
171            | ExprType::ConcatOp
172            | ExprType::ByteaConcatOp
173            | ExprType::BoolOut
174            | ExprType::OctetLength
175            | ExprType::BitLength
176            | ExprType::Overlay
177            | ExprType::RegexpMatch
178            | ExprType::RegexpReplace
179            | ExprType::RegexpCount
180            | ExprType::RegexpSplitToArray
181            | ExprType::RegexpEq
182            | ExprType::Pow
183            | ExprType::Exp
184            | ExprType::Chr
185            | ExprType::StartsWith
186            | ExprType::Initcap
187            | ExprType::Lpad
188            | ExprType::Rpad
189            | ExprType::Reverse
190            | ExprType::Strpos
191            | ExprType::ToAscii
192            | ExprType::ToHex
193            | ExprType::QuoteIdent
194            | ExprType::QuoteLiteral
195            | ExprType::Sin
196            | ExprType::Cos
197            | ExprType::Tan
198            | ExprType::Cot
199            | ExprType::Asin
200            | ExprType::Acos
201            | ExprType::Acosd
202            | ExprType::Atan
203            | ExprType::Atan2
204            | ExprType::Atand
205            | ExprType::Atan2d
206            | ExprType::Sind
207            | ExprType::Cosd
208            | ExprType::Cotd
209            | ExprType::Tand
210            | ExprType::Asind
211            | ExprType::Sqrt
212            | ExprType::Degrees
213            | ExprType::Radians
214            | ExprType::Cosh
215            | ExprType::Tanh
216            | ExprType::Coth
217            | ExprType::Asinh
218            | ExprType::Acosh
219            | ExprType::Atanh
220            | ExprType::Sinh
221            | ExprType::Trunc
222            | ExprType::Ln
223            | ExprType::Log10
224            | ExprType::Cbrt
225            | ExprType::Sign
226            | ExprType::Scale
227            | ExprType::MinScale
228            | ExprType::TrimScale
229            | ExprType::Encode
230            | ExprType::Decode
231            | ExprType::Sha1
232            | ExprType::Sha224
233            | ExprType::Sha256
234            | ExprType::Sha384
235            | ExprType::Sha512
236            | ExprType::Hmac
237            | ExprType::SecureCompare
238            | ExprType::Left
239            | ExprType::Right
240            | ExprType::Format
241            | ExprType::FormatVariadic
242            | ExprType::PgwireSend
243            | ExprType::PgwireRecv
244            | ExprType::ConvertFrom
245            | ExprType::ConvertTo
246            | ExprType::Decrypt
247            | ExprType::Encrypt
248            | ExprType::Neg
249            | ExprType::Field
250            | ExprType::Array
251            | ExprType::ArrayAccess
252            | ExprType::Row
253            | ExprType::ArrayToString
254            | ExprType::ArrayRangeAccess
255            | ExprType::ArrayCat
256            | ExprType::ArrayAppend
257            | ExprType::ArrayPrepend
258            | ExprType::FormatType
259            | ExprType::ArrayDistinct
260            | ExprType::ArrayLength
261            | ExprType::Cardinality
262            | ExprType::ArrayRemove
263            | ExprType::ArrayPositions
264            | ExprType::TrimArray
265            | ExprType::StringToArray
266            | ExprType::ArrayPosition
267            | ExprType::ArrayReplace
268            | ExprType::ArrayDims
269            | ExprType::ArrayTransform
270            | ExprType::ArrayMin
271            | ExprType::ArrayMax
272            | ExprType::ArraySum
273            | ExprType::ArraySort
274            | ExprType::ArrayContains
275            | ExprType::ArrayContained
276            | ExprType::ArrayFlatten
277            | ExprType::HexToInt256
278            | ExprType::JsonbAccess
279            | ExprType::JsonbAccessStr
280            | ExprType::JsonbExtractPath
281            | ExprType::JsonbExtractPathVariadic
282            | ExprType::JsonbExtractPathText
283            | ExprType::JsonbExtractPathTextVariadic
284            | ExprType::JsonbTypeof
285            | ExprType::JsonbArrayLength
286            | ExprType::IsJson
287            | ExprType::JsonbConcat
288            | ExprType::JsonbObject
289            | ExprType::JsonbPretty
290            | ExprType::JsonbContains
291            | ExprType::JsonbContained
292            | ExprType::JsonbExists
293            | ExprType::JsonbExistsAny
294            | ExprType::JsonbExistsAll
295            | ExprType::JsonbDeletePath
296            | ExprType::JsonbStripNulls
297            | ExprType::ToJsonb
298            | ExprType::JsonbBuildArray
299            | ExprType::JsonbBuildArrayVariadic
300            | ExprType::JsonbBuildObject
301            | ExprType::JsonbBuildObjectVariadic
302            | ExprType::JsonbPathExists
303            | ExprType::JsonbPathMatch
304            | ExprType::JsonbPathQueryArray
305            | ExprType::JsonbPathQueryFirst
306            | ExprType::JsonbPopulateRecord
307            | ExprType::JsonbToArray
308            | ExprType::JsonbToRecord
309            | ExprType::JsonbSet
310            | ExprType::JsonbPopulateMap
311            | ExprType::MapFromEntries
312            | ExprType::MapAccess
313            | ExprType::MapKeys
314            | ExprType::MapValues
315            | ExprType::MapEntries
316            | ExprType::MapFromKeyValues
317            | ExprType::MapCat
318            | ExprType::MapContains
319            | ExprType::MapDelete
320            | ExprType::MapFilter
321            | ExprType::MapInsert
322            | ExprType::MapLength
323            | ExprType::Vnode
324            | ExprType::VnodeUser
325            | ExprType::TestFeature
326            | ExprType::License
327            | ExprType::Proctime
328            | ExprType::PgSleep
329            | ExprType::PgSleepFor
330            | ExprType::PgSleepUntil
331            | ExprType::CastRegclass
332            | ExprType::PgGetIndexdef
333            | ExprType::ColDescription
334            | ExprType::PgGetViewdef
335            | ExprType::PgGetUserbyid
336            | ExprType::PgIndexesSize
337            | ExprType::PgRelationSize
338            | ExprType::PgGetSerialSequence
339            | ExprType::PgIndexColumnHasProperty
340            | ExprType::PgIsInRecovery
341            | ExprType::PgTableIsVisible
342            | ExprType::RwRecoveryStatus
343            | ExprType::IcebergTransform
344            | ExprType::HasTablePrivilege
345            | ExprType::HasFunctionPrivilege
346            | ExprType::HasAnyColumnPrivilege
347            | ExprType::HasSchemaPrivilege
348            | ExprType::InetAton
349            | ExprType::InetNtoa
350            | ExprType::CompositeCast
351            | ExprType::RwEpochToTs
352            | ExprType::OpenaiEmbedding
353            | ExprType::HasDatabasePrivilege
354            | ExprType::Random => false,
355            ExprType::Unspecified => unreachable!(),
356        }
357    }
358
359    fn any_null(&self, func_call: &FunctionCall) -> bool {
360        func_call
361            .inputs()
362            .iter()
363            .any(|expr| self.is_null_visit(expr))
364    }
365
366    fn all_null(&self, func_call: &FunctionCall) -> bool {
367        func_call
368            .inputs()
369            .iter()
370            .all(|expr| self.is_null_visit(expr))
371    }
372}
373
374#[cfg(test)]
375mod tests {
376    use risingwave_common::types::DataType;
377
378    use super::*;
379    use crate::expr::ExprImpl::Literal;
380
381    #[test]
382    fn test_literal() {
383        let null_columns = FixedBitSet::with_capacity(1);
384        let expr = Literal(crate::expr::Literal::new(None, DataType::Varchar).into());
385        assert!(Strong::is_null(&expr, null_columns.clone()));
386
387        let expr = Literal(
388            crate::expr::Literal::new(Some("test".to_owned().into()), DataType::Varchar).into(),
389        );
390        assert!(!Strong::is_null(&expr, null_columns));
391    }
392
393    #[test]
394    fn test_input_ref1() {
395        let null_columns = FixedBitSet::with_capacity(2);
396        let expr = InputRef::new(0, DataType::Varchar).into();
397        assert!(!Strong::is_null(&expr, null_columns.clone()));
398
399        let expr = InputRef::new(1, DataType::Varchar).into();
400        assert!(!Strong::is_null(&expr, null_columns));
401    }
402
403    #[test]
404    fn test_input_ref2() {
405        let mut null_columns = FixedBitSet::with_capacity(2);
406        null_columns.insert(0);
407        null_columns.insert(1);
408        let expr = InputRef::new(0, DataType::Varchar).into();
409        assert!(Strong::is_null(&expr, null_columns.clone()));
410
411        let expr = InputRef::new(1, DataType::Varchar).into();
412        assert!(Strong::is_null(&expr, null_columns));
413    }
414
415    #[test]
416    fn test_c1_equal_1_or_c2_is_null() {
417        let mut null_columns = FixedBitSet::with_capacity(2);
418        null_columns.insert(0);
419        let expr = FunctionCall::new_unchecked(
420            ExprType::Or,
421            vec![
422                FunctionCall::new_unchecked(
423                    ExprType::Equal,
424                    vec![
425                        InputRef::new(0, DataType::Int64).into(),
426                        Literal(crate::expr::Literal::new(Some(1.into()), DataType::Int32).into()),
427                    ],
428                    DataType::Boolean,
429                )
430                .into(),
431                FunctionCall::new_unchecked(
432                    ExprType::IsNull,
433                    vec![InputRef::new(1, DataType::Int64).into()],
434                    DataType::Boolean,
435                )
436                .into(),
437            ],
438            DataType::Boolean,
439        )
440        .into();
441        assert!(!Strong::is_null(&expr, null_columns));
442    }
443
444    #[test]
445    fn test_divide() {
446        let mut null_columns = FixedBitSet::with_capacity(2);
447        null_columns.insert(0);
448        null_columns.insert(1);
449        let expr = FunctionCall::new_unchecked(
450            ExprType::Divide,
451            vec![
452                InputRef::new(0, DataType::Decimal).into(),
453                InputRef::new(1, DataType::Decimal).into(),
454            ],
455            DataType::Varchar,
456        )
457        .into();
458        assert!(Strong::is_null(&expr, null_columns));
459    }
460
461    /// generate a test case for (0.8 * sum / count) where sum is null and count is not null
462    #[test]
463    fn test_multiply_divide() {
464        let mut null_columns = FixedBitSet::with_capacity(2);
465        null_columns.insert(0);
466        let expr = FunctionCall::new_unchecked(
467            ExprType::Multiply,
468            vec![
469                Literal(crate::expr::Literal::new(Some(0.8f64.into()), DataType::Float64).into()),
470                FunctionCall::new_unchecked(
471                    ExprType::Divide,
472                    vec![
473                        InputRef::new(0, DataType::Decimal).into(),
474                        InputRef::new(1, DataType::Decimal).into(),
475                    ],
476                    DataType::Decimal,
477                )
478                .into(),
479            ],
480            DataType::Decimal,
481        )
482        .into();
483        assert!(Strong::is_null(&expr, null_columns));
484    }
485
486    /// generate test cases for is not null
487    macro_rules! gen_test {
488        ($func:ident, $expr:expr, $expected:expr) => {
489            #[test]
490            fn $func() {
491                let null_columns = FixedBitSet::with_capacity(2);
492                let expr = $expr;
493                assert_eq!(Strong::is_null(&expr, null_columns), $expected);
494            }
495        };
496    }
497
498    gen_test!(
499        test_is_not_null,
500        FunctionCall::new_unchecked(
501            ExprType::IsNotNull,
502            vec![InputRef::new(0, DataType::Varchar).into()],
503            DataType::Varchar
504        )
505        .into(),
506        false
507    );
508    gen_test!(
509        test_is_null,
510        FunctionCall::new_unchecked(
511            ExprType::IsNull,
512            vec![InputRef::new(0, DataType::Varchar).into()],
513            DataType::Varchar
514        )
515        .into(),
516        false
517    );
518    gen_test!(
519        test_is_distinct_from,
520        FunctionCall::new_unchecked(
521            ExprType::IsDistinctFrom,
522            vec![
523                InputRef::new(0, DataType::Varchar).into(),
524                InputRef::new(1, DataType::Varchar).into()
525            ],
526            DataType::Varchar
527        )
528        .into(),
529        false
530    );
531    gen_test!(
532        test_is_not_distinct_from,
533        FunctionCall::new_unchecked(
534            ExprType::IsNotDistinctFrom,
535            vec![
536                InputRef::new(0, DataType::Varchar).into(),
537                InputRef::new(1, DataType::Varchar).into()
538            ],
539            DataType::Varchar
540        )
541        .into(),
542        false
543    );
544    gen_test!(
545        test_is_true,
546        FunctionCall::new_unchecked(
547            ExprType::IsTrue,
548            vec![InputRef::new(0, DataType::Varchar).into()],
549            DataType::Varchar
550        )
551        .into(),
552        false
553    );
554    gen_test!(
555        test_is_not_true,
556        FunctionCall::new_unchecked(
557            ExprType::IsNotTrue,
558            vec![InputRef::new(0, DataType::Varchar).into()],
559            DataType::Varchar
560        )
561        .into(),
562        false
563    );
564    gen_test!(
565        test_is_false,
566        FunctionCall::new_unchecked(
567            ExprType::IsFalse,
568            vec![InputRef::new(0, DataType::Varchar).into()],
569            DataType::Varchar
570        )
571        .into(),
572        false
573    );
574}
risingwave_frontend/optimizer/plan_expr_visitor/strong.rs

risingwave_frontend/optimizer/plan_expr_visitor/
strong.rs
