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alexey-milovidovalexey-milovidov
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Merge pull request #12271 from ClickHouse/fix-logical-functions-review
Fix minor issues in ternary logic
2 parents abf1e01 + 5ef4e90 commit d0d1590

4 files changed

Lines changed: 44 additions & 5 deletions

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‎src/Functions/FunctionsLogical.cpp‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -336,7 +336,7 @@ static void executeForTernaryLogicImpl(ColumnRawPtrs arguments, ColumnWithTypeAn
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const bool has_consts = extractConstColumnsAsTernary<Op>(arguments, const_3v_value);
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/// If the constant value uniquely determines the result, return it.
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if (has_consts && (arguments.empty() || Op::isSaturatedValue(const_3v_value)))
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if (has_consts && (arguments.empty() || Op::isSaturatedValueTernary(const_3v_value)))
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{
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result_info.column = ColumnConst::create(
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buildColumnFromTernaryData(UInt8Container({const_3v_value}), result_info.type->isNullable()),
@@ -498,7 +498,8 @@ DataTypePtr FunctionAnyArityLogical<Impl, Name>::getReturnTypeImpl(const DataTyp
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}
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template <typename Impl, typename Name>
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void FunctionAnyArityLogical<Impl, Name>::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result_index, size_t input_rows_count)
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void FunctionAnyArityLogical<Impl, Name>::executeImpl(
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Block & block, const ColumnNumbers & arguments, size_t result_index, size_t input_rows_count)
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{
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ColumnRawPtrs args_in;
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for (const auto arg_index : arguments)

‎src/Functions/FunctionsLogical.h‎

Lines changed: 22 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -36,9 +36,21 @@ namespace Ternary
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{
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using ResultType = UInt8;
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static constexpr UInt8 False = 0;
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static constexpr UInt8 True = -1;
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static constexpr UInt8 Null = 1;
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/** These carefully picked values magically work so bitwise "and", "or" on them
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* corresponds to the expected results in three-valued logic.
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*
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* False and True are represented by all-0 and all-1 bits, so all bitwise operations on them work as expected.
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* Null is represented as single 1 bit. So, it is something in between False and True.
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* And "or" works like maximum and "and" works like minimum:
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* "or" keeps True as is and lifts False with Null to Null.
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* "and" keeps False as is and downs True with Null to Null.
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*
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* This logic does not apply for "not" and "xor" - they work with default implementation for NULLs:
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* anything with NULL returns NULL, otherwise use conventional two-valued logic.
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*/
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static constexpr UInt8 False = 0; /// All zero bits.
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static constexpr UInt8 True = -1; /// All one bits.
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static constexpr UInt8 Null = 1; /// Single one bit.
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template <typename T>
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inline ResultType makeValue(T value)
@@ -61,9 +73,16 @@ struct AndImpl
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using ResultType = UInt8;
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static inline constexpr bool isSaturable() { return true; }
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/// Final value in two-valued logic (no further operations with True, False will change this value)
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static inline constexpr bool isSaturatedValue(bool a) { return !a; }
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/// Final value in three-valued logic (no further operations with True, False, Null will change this value)
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static inline constexpr bool isSaturatedValueTernary(UInt8 a) { return a == Ternary::False; }
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static inline constexpr ResultType apply(UInt8 a, UInt8 b) { return a & b; }
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/// Will use three-valued logic for NULLs (see above) or default implementation (any operation with NULL returns NULL).
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static inline constexpr bool specialImplementationForNulls() { return true; }
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};
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‎tests/queries/0_stateless/01376_null_logical.reference‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
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1
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1
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0
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0
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\N
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\N
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\N
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\N

‎tests/queries/0_stateless/01376_null_logical.sql‎

Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,11 @@
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SELECT NULL OR 1;
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SELECT materialize(NULL) OR materialize(1);
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SELECT NULL AND 0;
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SELECT materialize(NULL) AND materialize(0);
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SELECT NULL OR 0;
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SELECT materialize(NULL) OR materialize(0);
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SELECT NULL AND 1;
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SELECT materialize(NULL) AND materialize(1);

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