risingwave_frontend/optimizer/plan_expr_visitor/
strong.rs

1// Copyright 2024 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::Subvector
119            | ExprType::Greatest
120            | ExprType::Least => self.any_null(func_call),
121            // ALL: This kind of expression is null if and only if all of its arguments are null.
122            ExprType::And | ExprType::Or | ExprType::Coalesce => self.all_null(func_call),
123            // TODO: Function like case when is important but current its structure is complicated, so we need to implement it later if necessary.
124            // Assume that any other expressions cannot be simplified.
125            ExprType::In
126            | ExprType::Some
127            | ExprType::All
128            | ExprType::BitwiseAnd
129            | ExprType::BitwiseOr
130            | ExprType::BitwiseXor
131            | ExprType::BitwiseNot
132            | ExprType::BitwiseShiftLeft
133            | ExprType::BitwiseShiftRight
134            | ExprType::DatePart
135            | ExprType::TumbleStart
136            | ExprType::MakeDate
137            | ExprType::MakeTime
138            | ExprType::MakeTimestamp
139            | ExprType::SecToTimestamptz
140            | ExprType::AtTimeZone
141            | ExprType::DateTrunc
142            | ExprType::DateBin
143            | ExprType::CharToTimestamptz
144            | ExprType::CharToDate
145            | ExprType::CastWithTimeZone
146            | ExprType::SubtractWithTimeZone
147            | ExprType::MakeTimestamptz
148            | ExprType::Substr
149            | ExprType::Length
150            | ExprType::ILike
151            | ExprType::SimilarToEscape
152            | ExprType::Upper
153            | ExprType::Lower
154            | ExprType::Replace
155            | ExprType::Position
156            | ExprType::Case
157            | ExprType::ConstantLookup
158            | ExprType::RoundDigit
159            | ExprType::Round
160            | ExprType::Ascii
161            | ExprType::Translate
162            | ExprType::Concat
163            | ExprType::ConcatVariadic
164            | ExprType::ConcatWs
165            | ExprType::ConcatWsVariadic
166            | ExprType::Abs
167            | ExprType::SplitPart
168            | ExprType::ToChar
169            | ExprType::Md5
170            | ExprType::CharLength
171            | ExprType::Repeat
172            | ExprType::ConcatOp
173            | ExprType::ByteaConcatOp
174            | ExprType::BoolOut
175            | ExprType::OctetLength
176            | ExprType::BitLength
177            | ExprType::Overlay
178            | ExprType::RegexpMatch
179            | ExprType::RegexpReplace
180            | ExprType::RegexpCount
181            | ExprType::RegexpSplitToArray
182            | ExprType::RegexpEq
183            | ExprType::Pow
184            | ExprType::Exp
185            | ExprType::Chr
186            | ExprType::StartsWith
187            | ExprType::Initcap
188            | ExprType::Lpad
189            | ExprType::Rpad
190            | ExprType::Reverse
191            | ExprType::Strpos
192            | ExprType::ToAscii
193            | ExprType::ToHex
194            | ExprType::QuoteIdent
195            | ExprType::QuoteLiteral
196            | ExprType::Sin
197            | ExprType::Cos
198            | ExprType::Tan
199            | ExprType::Cot
200            | ExprType::Asin
201            | ExprType::Acos
202            | ExprType::Acosd
203            | ExprType::Atan
204            | ExprType::Atan2
205            | ExprType::Atand
206            | ExprType::Atan2d
207            | ExprType::Sind
208            | ExprType::Cosd
209            | ExprType::Cotd
210            | ExprType::Tand
211            | ExprType::Asind
212            | ExprType::Sqrt
213            | ExprType::Degrees
214            | ExprType::Radians
215            | ExprType::Cosh
216            | ExprType::Tanh
217            | ExprType::Coth
218            | ExprType::Asinh
219            | ExprType::Acosh
220            | ExprType::Atanh
221            | ExprType::Sinh
222            | ExprType::Trunc
223            | ExprType::Ln
224            | ExprType::Log10
225            | ExprType::Cbrt
226            | ExprType::Sign
227            | ExprType::Scale
228            | ExprType::MinScale
229            | ExprType::TrimScale
230            | ExprType::Gamma
231            | ExprType::Lgamma
232            | ExprType::Encode
233            | ExprType::Decode
234            | ExprType::Sha1
235            | ExprType::Sha224
236            | ExprType::Sha256
237            | ExprType::Sha384
238            | ExprType::Sha512
239            | ExprType::GetBit
240            | ExprType::GetByte
241            | ExprType::SetBit
242            | ExprType::SetByte
243            | ExprType::BitCount
244            | ExprType::Hmac
245            | ExprType::SecureCompare
246            | ExprType::Left
247            | ExprType::Right
248            | ExprType::Format
249            | ExprType::FormatVariadic
250            | ExprType::PgwireSend
251            | ExprType::PgwireRecv
252            | ExprType::ConvertFrom
253            | ExprType::ConvertTo
254            | ExprType::Decrypt
255            | ExprType::Encrypt
256            | ExprType::Neg
257            | ExprType::Field
258            | ExprType::Array
259            | ExprType::ArrayAccess
260            | ExprType::Row
261            | ExprType::ArrayToString
262            | ExprType::ArrayRangeAccess
263            | ExprType::ArrayCat
264            | ExprType::ArrayAppend
265            | ExprType::ArrayPrepend
266            | ExprType::FormatType
267            | ExprType::ArrayDistinct
268            | ExprType::ArrayLength
269            | ExprType::Cardinality
270            | ExprType::ArrayRemove
271            | ExprType::ArrayPositions
272            | ExprType::TrimArray
273            | ExprType::StringToArray
274            | ExprType::ArrayPosition
275            | ExprType::ArrayReplace
276            | ExprType::ArrayDims
277            | ExprType::ArrayTransform
278            | ExprType::ArrayMin
279            | ExprType::ArrayMax
280            | ExprType::ArraySum
281            | ExprType::ArraySort
282            | ExprType::ArrayReverse
283            | ExprType::ArrayContains
284            | ExprType::ArrayContained
285            | ExprType::ArrayFlatten
286            | ExprType::HexToInt256
287            | ExprType::JsonbAccess
288            | ExprType::JsonbAccessStr
289            | ExprType::JsonbExtractPath
290            | ExprType::JsonbExtractPathVariadic
291            | ExprType::JsonbExtractPathText
292            | ExprType::JsonbExtractPathTextVariadic
293            | ExprType::JsonbTypeof
294            | ExprType::JsonbArrayLength
295            | ExprType::IsJson
296            | ExprType::JsonbConcat
297            | ExprType::JsonbObject
298            | ExprType::JsonbPretty
299            | ExprType::JsonbContains
300            | ExprType::JsonbContained
301            | ExprType::JsonbExists
302            | ExprType::JsonbExistsAny
303            | ExprType::JsonbExistsAll
304            | ExprType::JsonbDeletePath
305            | ExprType::JsonbStripNulls
306            | ExprType::ToJsonb
307            | ExprType::JsonbBuildArray
308            | ExprType::JsonbBuildArrayVariadic
309            | ExprType::JsonbBuildObject
310            | ExprType::JsonbBuildObjectVariadic
311            | ExprType::JsonbPathExists
312            | ExprType::JsonbPathMatch
313            | ExprType::JsonbPathQueryArray
314            | ExprType::JsonbPathQueryFirst
315            | ExprType::JsonbPopulateRecord
316            | ExprType::JsonbToArray
317            | ExprType::JsonbToRecord
318            | ExprType::JsonbSet
319            | ExprType::JsonbPopulateMap
320            | ExprType::MapFromEntries
321            | ExprType::MapAccess
322            | ExprType::MapKeys
323            | ExprType::MapValues
324            | ExprType::MapEntries
325            | ExprType::MapFromKeyValues
326            | ExprType::MapCat
327            | ExprType::MapContains
328            | ExprType::MapDelete
329            | ExprType::MapFilter
330            | ExprType::MapInsert
331            | ExprType::MapLength
332            | ExprType::Vnode
333            | ExprType::VnodeUser
334            | ExprType::TestFeature
335            | ExprType::License
336            | ExprType::Proctime
337            | ExprType::PgSleep
338            | ExprType::PgSleepFor
339            | ExprType::PgSleepUntil
340            | ExprType::CastRegclass
341            | ExprType::PgGetIndexdef
342            | ExprType::ColDescription
343            | ExprType::PgGetViewdef
344            | ExprType::PgGetUserbyid
345            | ExprType::PgIndexesSize
346            | ExprType::PgRelationSize
347            | ExprType::PgGetSerialSequence
348            | ExprType::PgIndexColumnHasProperty
349            | ExprType::PgIsInRecovery
350            | ExprType::PgTableIsVisible
351            | ExprType::RwRecoveryStatus
352            | ExprType::RwClusterId
353            | ExprType::RwFragmentVnodes
354            | ExprType::RwActorVnodes
355            | ExprType::IcebergTransform
356            | ExprType::HasTablePrivilege
357            | ExprType::HasFunctionPrivilege
358            | ExprType::HasAnyColumnPrivilege
359            | ExprType::HasSchemaPrivilege
360            | ExprType::InetAton
361            | ExprType::InetNtoa
362            | ExprType::CompositeCast
363            | ExprType::RwEpochToTs
364            | ExprType::OpenaiEmbedding
365            | ExprType::HasDatabasePrivilege
366            | ExprType::Random => false,
367            ExprType::Unspecified => unreachable!(),
368        }
369    }
370
371    fn any_null(&self, func_call: &FunctionCall) -> bool {
372        func_call
373            .inputs()
374            .iter()
375            .any(|expr| self.is_null_visit(expr))
376    }
377
378    fn all_null(&self, func_call: &FunctionCall) -> bool {
379        func_call
380            .inputs()
381            .iter()
382            .all(|expr| self.is_null_visit(expr))
383    }
384}
385
386#[cfg(test)]
387mod tests {
388    use risingwave_common::types::DataType;
389
390    use super::*;
391    use crate::expr::ExprImpl::Literal;
392
393    #[test]
394    fn test_literal() {
395        let null_columns = FixedBitSet::with_capacity(1);
396        let expr = Literal(crate::expr::Literal::new(None, DataType::Varchar).into());
397        assert!(Strong::is_null(&expr, null_columns.clone()));
398
399        let expr = Literal(
400            crate::expr::Literal::new(Some("test".to_owned().into()), DataType::Varchar).into(),
401        );
402        assert!(!Strong::is_null(&expr, null_columns));
403    }
404
405    #[test]
406    fn test_input_ref1() {
407        let null_columns = FixedBitSet::with_capacity(2);
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_input_ref2() {
417        let mut null_columns = FixedBitSet::with_capacity(2);
418        null_columns.insert(0);
419        null_columns.insert(1);
420        let expr = InputRef::new(0, DataType::Varchar).into();
421        assert!(Strong::is_null(&expr, null_columns.clone()));
422
423        let expr = InputRef::new(1, DataType::Varchar).into();
424        assert!(Strong::is_null(&expr, null_columns));
425    }
426
427    #[test]
428    fn test_c1_equal_1_or_c2_is_null() {
429        let mut null_columns = FixedBitSet::with_capacity(2);
430        null_columns.insert(0);
431        let expr = FunctionCall::new_unchecked(
432            ExprType::Or,
433            vec![
434                FunctionCall::new_unchecked(
435                    ExprType::Equal,
436                    vec![
437                        InputRef::new(0, DataType::Int64).into(),
438                        Literal(crate::expr::Literal::new(Some(1.into()), DataType::Int32).into()),
439                    ],
440                    DataType::Boolean,
441                )
442                .into(),
443                FunctionCall::new_unchecked(
444                    ExprType::IsNull,
445                    vec![InputRef::new(1, DataType::Int64).into()],
446                    DataType::Boolean,
447                )
448                .into(),
449            ],
450            DataType::Boolean,
451        )
452        .into();
453        assert!(!Strong::is_null(&expr, null_columns));
454    }
455
456    #[test]
457    fn test_divide() {
458        let mut null_columns = FixedBitSet::with_capacity(2);
459        null_columns.insert(0);
460        null_columns.insert(1);
461        let expr = 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::Varchar,
468        )
469        .into();
470        assert!(Strong::is_null(&expr, null_columns));
471    }
472
473    /// generate a test case for (0.8 * sum / count) where sum is null and count is not null
474    #[test]
475    fn test_multiply_divide() {
476        let mut null_columns = FixedBitSet::with_capacity(2);
477        null_columns.insert(0);
478        let expr = FunctionCall::new_unchecked(
479            ExprType::Multiply,
480            vec![
481                Literal(crate::expr::Literal::new(Some(0.8f64.into()), DataType::Float64).into()),
482                FunctionCall::new_unchecked(
483                    ExprType::Divide,
484                    vec![
485                        InputRef::new(0, DataType::Decimal).into(),
486                        InputRef::new(1, DataType::Decimal).into(),
487                    ],
488                    DataType::Decimal,
489                )
490                .into(),
491            ],
492            DataType::Decimal,
493        )
494        .into();
495        assert!(Strong::is_null(&expr, null_columns));
496    }
497
498    /// generate test cases for is not null
499    macro_rules! gen_test {
500        ($func:ident, $expr:expr, $expected:expr) => {
501            #[test]
502            fn $func() {
503                let null_columns = FixedBitSet::with_capacity(2);
504                let expr = $expr;
505                assert_eq!(Strong::is_null(&expr, null_columns), $expected);
506            }
507        };
508    }
509
510    gen_test!(
511        test_is_not_null,
512        FunctionCall::new_unchecked(
513            ExprType::IsNotNull,
514            vec![InputRef::new(0, DataType::Varchar).into()],
515            DataType::Varchar
516        )
517        .into(),
518        false
519    );
520    gen_test!(
521        test_is_null,
522        FunctionCall::new_unchecked(
523            ExprType::IsNull,
524            vec![InputRef::new(0, DataType::Varchar).into()],
525            DataType::Varchar
526        )
527        .into(),
528        false
529    );
530    gen_test!(
531        test_is_distinct_from,
532        FunctionCall::new_unchecked(
533            ExprType::IsDistinctFrom,
534            vec![
535                InputRef::new(0, DataType::Varchar).into(),
536                InputRef::new(1, DataType::Varchar).into()
537            ],
538            DataType::Varchar
539        )
540        .into(),
541        false
542    );
543    gen_test!(
544        test_is_not_distinct_from,
545        FunctionCall::new_unchecked(
546            ExprType::IsNotDistinctFrom,
547            vec![
548                InputRef::new(0, DataType::Varchar).into(),
549                InputRef::new(1, DataType::Varchar).into()
550            ],
551            DataType::Varchar
552        )
553        .into(),
554        false
555    );
556    gen_test!(
557        test_is_true,
558        FunctionCall::new_unchecked(
559            ExprType::IsTrue,
560            vec![InputRef::new(0, DataType::Varchar).into()],
561            DataType::Varchar
562        )
563        .into(),
564        false
565    );
566    gen_test!(
567        test_is_not_true,
568        FunctionCall::new_unchecked(
569            ExprType::IsNotTrue,
570            vec![InputRef::new(0, DataType::Varchar).into()],
571            DataType::Varchar
572        )
573        .into(),
574        false
575    );
576    gen_test!(
577        test_is_false,
578        FunctionCall::new_unchecked(
579            ExprType::IsFalse,
580            vec![InputRef::new(0, DataType::Varchar).into()],
581            DataType::Varchar
582        )
583        .into(),
584        false
585    );
586}
risingwave_frontend/optimizer/plan_expr_visitor/strong.rs

risingwave_frontend/optimizer/plan_expr_visitor/
strong.rs
