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

risingwave_frontend/optimizer/plan_expr_visitor/
strong.rs
