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::Greatest
113            | ExprType::Least => self.any_null(func_call),
114            // ALL: This kind of expression is null if and only if all of its arguments are null.
115            ExprType::And | ExprType::Or | ExprType::Coalesce => self.all_null(func_call),
116            // TODO: Function like case when is important but current its structure is complicated, so we need to implement it later if necessary.
117            // Assume that any other expressions cannot be simplified.
118            ExprType::In
119            | ExprType::Some
120            | ExprType::All
121            | ExprType::BitwiseAnd
122            | ExprType::BitwiseOr
123            | ExprType::BitwiseXor
124            | ExprType::BitwiseNot
125            | ExprType::BitwiseShiftLeft
126            | ExprType::BitwiseShiftRight
127            | ExprType::DatePart
128            | ExprType::TumbleStart
129            | ExprType::MakeDate
130            | ExprType::MakeTime
131            | ExprType::MakeTimestamp
132            | ExprType::SecToTimestamptz
133            | ExprType::AtTimeZone
134            | ExprType::DateTrunc
135            | ExprType::DateBin
136            | ExprType::CharToTimestamptz
137            | ExprType::CharToDate
138            | ExprType::CastWithTimeZone
139            | ExprType::SubtractWithTimeZone
140            | ExprType::MakeTimestamptz
141            | ExprType::Substr
142            | ExprType::Length
143            | ExprType::ILike
144            | ExprType::SimilarToEscape
145            | ExprType::Upper
146            | ExprType::Lower
147            | ExprType::Replace
148            | ExprType::Position
149            | ExprType::Case
150            | ExprType::ConstantLookup
151            | ExprType::RoundDigit
152            | ExprType::Round
153            | ExprType::Ascii
154            | ExprType::Translate
155            | ExprType::Concat
156            | ExprType::ConcatVariadic
157            | ExprType::ConcatWs
158            | ExprType::ConcatWsVariadic
159            | ExprType::Abs
160            | ExprType::SplitPart
161            | ExprType::ToChar
162            | ExprType::Md5
163            | ExprType::CharLength
164            | ExprType::Repeat
165            | ExprType::ConcatOp
166            | ExprType::ByteaConcatOp
167            | ExprType::BoolOut
168            | ExprType::OctetLength
169            | ExprType::BitLength
170            | ExprType::Overlay
171            | ExprType::RegexpMatch
172            | ExprType::RegexpReplace
173            | ExprType::RegexpCount
174            | ExprType::RegexpSplitToArray
175            | ExprType::RegexpEq
176            | ExprType::Pow
177            | ExprType::Exp
178            | ExprType::Chr
179            | ExprType::StartsWith
180            | ExprType::Initcap
181            | ExprType::Lpad
182            | ExprType::Rpad
183            | ExprType::Reverse
184            | ExprType::Strpos
185            | ExprType::ToAscii
186            | ExprType::ToHex
187            | ExprType::QuoteIdent
188            | ExprType::QuoteLiteral
189            | ExprType::Sin
190            | ExprType::Cos
191            | ExprType::Tan
192            | ExprType::Cot
193            | ExprType::Asin
194            | ExprType::Acos
195            | ExprType::Acosd
196            | ExprType::Atan
197            | ExprType::Atan2
198            | ExprType::Atand
199            | ExprType::Atan2d
200            | ExprType::Sind
201            | ExprType::Cosd
202            | ExprType::Cotd
203            | ExprType::Tand
204            | ExprType::Asind
205            | ExprType::Sqrt
206            | ExprType::Degrees
207            | ExprType::Radians
208            | ExprType::Cosh
209            | ExprType::Tanh
210            | ExprType::Coth
211            | ExprType::Asinh
212            | ExprType::Acosh
213            | ExprType::Atanh
214            | ExprType::Sinh
215            | ExprType::Trunc
216            | ExprType::Ln
217            | ExprType::Log10
218            | ExprType::Cbrt
219            | ExprType::Sign
220            | ExprType::Scale
221            | ExprType::MinScale
222            | ExprType::TrimScale
223            | ExprType::Encode
224            | ExprType::Decode
225            | ExprType::Sha1
226            | ExprType::Sha224
227            | ExprType::Sha256
228            | ExprType::Sha384
229            | ExprType::Sha512
230            | ExprType::Hmac
231            | ExprType::SecureCompare
232            | ExprType::Left
233            | ExprType::Right
234            | ExprType::Format
235            | ExprType::FormatVariadic
236            | ExprType::PgwireSend
237            | ExprType::PgwireRecv
238            | ExprType::ConvertFrom
239            | ExprType::ConvertTo
240            | ExprType::Decrypt
241            | ExprType::Encrypt
242            | ExprType::Neg
243            | ExprType::Field
244            | ExprType::Array
245            | ExprType::ArrayAccess
246            | ExprType::Row
247            | ExprType::ArrayToString
248            | ExprType::ArrayRangeAccess
249            | ExprType::ArrayCat
250            | ExprType::ArrayAppend
251            | ExprType::ArrayPrepend
252            | ExprType::FormatType
253            | ExprType::ArrayDistinct
254            | ExprType::ArrayLength
255            | ExprType::Cardinality
256            | ExprType::ArrayRemove
257            | ExprType::ArrayPositions
258            | ExprType::TrimArray
259            | ExprType::StringToArray
260            | ExprType::ArrayPosition
261            | ExprType::ArrayReplace
262            | ExprType::ArrayDims
263            | ExprType::ArrayTransform
264            | ExprType::ArrayMin
265            | ExprType::ArrayMax
266            | ExprType::ArraySum
267            | ExprType::ArraySort
268            | ExprType::ArrayContains
269            | ExprType::ArrayContained
270            | ExprType::ArrayFlatten
271            | ExprType::HexToInt256
272            | ExprType::JsonbAccess
273            | ExprType::JsonbAccessStr
274            | ExprType::JsonbExtractPath
275            | ExprType::JsonbExtractPathVariadic
276            | ExprType::JsonbExtractPathText
277            | ExprType::JsonbExtractPathTextVariadic
278            | ExprType::JsonbTypeof
279            | ExprType::JsonbArrayLength
280            | ExprType::IsJson
281            | ExprType::JsonbConcat
282            | ExprType::JsonbObject
283            | ExprType::JsonbPretty
284            | ExprType::JsonbContains
285            | ExprType::JsonbContained
286            | ExprType::JsonbExists
287            | ExprType::JsonbExistsAny
288            | ExprType::JsonbExistsAll
289            | ExprType::JsonbDeletePath
290            | ExprType::JsonbStripNulls
291            | ExprType::ToJsonb
292            | ExprType::JsonbBuildArray
293            | ExprType::JsonbBuildArrayVariadic
294            | ExprType::JsonbBuildObject
295            | ExprType::JsonbBuildObjectVariadic
296            | ExprType::JsonbPathExists
297            | ExprType::JsonbPathMatch
298            | ExprType::JsonbPathQueryArray
299            | ExprType::JsonbPathQueryFirst
300            | ExprType::JsonbPopulateRecord
301            | ExprType::JsonbToRecord
302            | ExprType::JsonbSet
303            | ExprType::JsonbPopulateMap
304            | ExprType::MapFromEntries
305            | ExprType::MapAccess
306            | ExprType::MapKeys
307            | ExprType::MapValues
308            | ExprType::MapEntries
309            | ExprType::MapFromKeyValues
310            | ExprType::MapCat
311            | ExprType::MapContains
312            | ExprType::MapDelete
313            | ExprType::MapFilter
314            | ExprType::MapInsert
315            | ExprType::MapLength
316            | ExprType::Vnode
317            | ExprType::VnodeUser
318            | ExprType::TestPaidTier
319            | ExprType::License
320            | ExprType::Proctime
321            | ExprType::PgSleep
322            | ExprType::PgSleepFor
323            | ExprType::PgSleepUntil
324            | ExprType::CastRegclass
325            | ExprType::PgGetIndexdef
326            | ExprType::ColDescription
327            | ExprType::PgGetViewdef
328            | ExprType::PgGetUserbyid
329            | ExprType::PgIndexesSize
330            | ExprType::PgRelationSize
331            | ExprType::PgGetSerialSequence
332            | ExprType::PgIndexColumnHasProperty
333            | ExprType::PgIsInRecovery
334            | ExprType::PgTableIsVisible
335            | ExprType::RwRecoveryStatus
336            | ExprType::IcebergTransform
337            | ExprType::HasTablePrivilege
338            | ExprType::HasFunctionPrivilege
339            | ExprType::HasAnyColumnPrivilege
340            | ExprType::HasSchemaPrivilege
341            | ExprType::InetAton
342            | ExprType::InetNtoa
343            | ExprType::CompositeCast
344            | ExprType::RwEpochToTs
345            | ExprType::OpenaiEmbedding => false,
346            ExprType::Unspecified => unreachable!(),
347        }
348    }
349
350    fn any_null(&self, func_call: &FunctionCall) -> bool {
351        func_call
352            .inputs()
353            .iter()
354            .any(|expr| self.is_null_visit(expr))
355    }
356
357    fn all_null(&self, func_call: &FunctionCall) -> bool {
358        func_call
359            .inputs()
360            .iter()
361            .all(|expr| self.is_null_visit(expr))
362    }
363}
364
365#[cfg(test)]
366mod tests {
367    use risingwave_common::types::DataType;
368
369    use super::*;
370    use crate::expr::ExprImpl::Literal;
371
372    #[test]
373    fn test_literal() {
374        let null_columns = FixedBitSet::with_capacity(1);
375        let expr = Literal(crate::expr::Literal::new(None, DataType::Varchar).into());
376        assert!(Strong::is_null(&expr, null_columns.clone()));
377
378        let expr = Literal(
379            crate::expr::Literal::new(Some("test".to_owned().into()), DataType::Varchar).into(),
380        );
381        assert!(!Strong::is_null(&expr, null_columns));
382    }
383
384    #[test]
385    fn test_input_ref1() {
386        let null_columns = FixedBitSet::with_capacity(2);
387        let expr = InputRef::new(0, DataType::Varchar).into();
388        assert!(!Strong::is_null(&expr, null_columns.clone()));
389
390        let expr = InputRef::new(1, DataType::Varchar).into();
391        assert!(!Strong::is_null(&expr, null_columns));
392    }
393
394    #[test]
395    fn test_input_ref2() {
396        let mut null_columns = FixedBitSet::with_capacity(2);
397        null_columns.insert(0);
398        null_columns.insert(1);
399        let expr = InputRef::new(0, DataType::Varchar).into();
400        assert!(Strong::is_null(&expr, null_columns.clone()));
401
402        let expr = InputRef::new(1, DataType::Varchar).into();
403        assert!(Strong::is_null(&expr, null_columns));
404    }
405
406    #[test]
407    fn test_c1_equal_1_or_c2_is_null() {
408        let mut null_columns = FixedBitSet::with_capacity(2);
409        null_columns.insert(0);
410        let expr = FunctionCall::new_unchecked(
411            ExprType::Or,
412            vec![
413                FunctionCall::new_unchecked(
414                    ExprType::Equal,
415                    vec![
416                        InputRef::new(0, DataType::Int64).into(),
417                        Literal(crate::expr::Literal::new(Some(1.into()), DataType::Int32).into()),
418                    ],
419                    DataType::Boolean,
420                )
421                .into(),
422                FunctionCall::new_unchecked(
423                    ExprType::IsNull,
424                    vec![InputRef::new(1, DataType::Int64).into()],
425                    DataType::Boolean,
426                )
427                .into(),
428            ],
429            DataType::Boolean,
430        )
431        .into();
432        assert!(!Strong::is_null(&expr, null_columns));
433    }
434
435    #[test]
436    fn test_divide() {
437        let mut null_columns = FixedBitSet::with_capacity(2);
438        null_columns.insert(0);
439        null_columns.insert(1);
440        let expr = FunctionCall::new_unchecked(
441            ExprType::Divide,
442            vec![
443                InputRef::new(0, DataType::Decimal).into(),
444                InputRef::new(1, DataType::Decimal).into(),
445            ],
446            DataType::Varchar,
447        )
448        .into();
449        assert!(Strong::is_null(&expr, null_columns));
450    }
451
452    /// generate a test case for (0.8 * sum / count) where sum is null and count is not null
453    #[test]
454    fn test_multiply_divide() {
455        let mut null_columns = FixedBitSet::with_capacity(2);
456        null_columns.insert(0);
457        let expr = FunctionCall::new_unchecked(
458            ExprType::Multiply,
459            vec![
460                Literal(crate::expr::Literal::new(Some(0.8f64.into()), DataType::Float64).into()),
461                FunctionCall::new_unchecked(
462                    ExprType::Divide,
463                    vec![
464                        InputRef::new(0, DataType::Decimal).into(),
465                        InputRef::new(1, DataType::Decimal).into(),
466                    ],
467                    DataType::Decimal,
468                )
469                .into(),
470            ],
471            DataType::Decimal,
472        )
473        .into();
474        assert!(Strong::is_null(&expr, null_columns));
475    }
476
477    /// generate test cases for is not null
478    macro_rules! gen_test {
479        ($func:ident, $expr:expr, $expected:expr) => {
480            #[test]
481            fn $func() {
482                let null_columns = FixedBitSet::with_capacity(2);
483                let expr = $expr;
484                assert_eq!(Strong::is_null(&expr, null_columns), $expected);
485            }
486        };
487    }
488
489    gen_test!(
490        test_is_not_null,
491        FunctionCall::new_unchecked(
492            ExprType::IsNotNull,
493            vec![InputRef::new(0, DataType::Varchar).into()],
494            DataType::Varchar
495        )
496        .into(),
497        false
498    );
499    gen_test!(
500        test_is_null,
501        FunctionCall::new_unchecked(
502            ExprType::IsNull,
503            vec![InputRef::new(0, DataType::Varchar).into()],
504            DataType::Varchar
505        )
506        .into(),
507        false
508    );
509    gen_test!(
510        test_is_distinct_from,
511        FunctionCall::new_unchecked(
512            ExprType::IsDistinctFrom,
513            vec![
514                InputRef::new(0, DataType::Varchar).into(),
515                InputRef::new(1, DataType::Varchar).into()
516            ],
517            DataType::Varchar
518        )
519        .into(),
520        false
521    );
522    gen_test!(
523        test_is_not_distinct_from,
524        FunctionCall::new_unchecked(
525            ExprType::IsNotDistinctFrom,
526            vec![
527                InputRef::new(0, DataType::Varchar).into(),
528                InputRef::new(1, DataType::Varchar).into()
529            ],
530            DataType::Varchar
531        )
532        .into(),
533        false
534    );
535    gen_test!(
536        test_is_true,
537        FunctionCall::new_unchecked(
538            ExprType::IsTrue,
539            vec![InputRef::new(0, DataType::Varchar).into()],
540            DataType::Varchar
541        )
542        .into(),
543        false
544    );
545    gen_test!(
546        test_is_not_true,
547        FunctionCall::new_unchecked(
548            ExprType::IsNotTrue,
549            vec![InputRef::new(0, DataType::Varchar).into()],
550            DataType::Varchar
551        )
552        .into(),
553        false
554    );
555    gen_test!(
556        test_is_false,
557        FunctionCall::new_unchecked(
558            ExprType::IsFalse,
559            vec![InputRef::new(0, DataType::Varchar).into()],
560            DataType::Varchar
561        )
562        .into(),
563        false
564    );
565}
risingwave_frontend/optimizer/plan_expr_visitor/strong.rs

risingwave_frontend/optimizer/plan_expr_visitor/
strong.rs
