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70d1adfe4b
* save format string for NetException * format exceptions * format exceptions 2 * format exceptions 3 * format exceptions 4 * format exceptions 5 * format exceptions 6 * fix * format exceptions 7 * format exceptions 8 * Update MergeTreeIndexGin.cpp * Update AggregateFunctionMap.cpp * Update AggregateFunctionMap.cpp * fix
121 lines
3.9 KiB
C++
121 lines
3.9 KiB
C++
#pragma once
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#include <Common/TargetSpecific.h>
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#include <DataTypes/DataTypesNumber.h>
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#include <Columns/ColumnVector.h>
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#include <Functions/IFunction.h>
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#include <Functions/PerformanceAdaptors.h>
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#include <IO/WriteHelpers.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
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}
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/** Pseudo-random number generation functions.
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* The function can be called without arguments or with one argument.
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* The argument is ignored and only serves to ensure that several calls to one function are considered different and do not stick together.
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*
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* Example:
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* SELECT rand(), rand() - will output two identical columns.
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* SELECT rand(1), rand(2) - will output two different columns.
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*
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* Non-cryptographic generators:
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*
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* rand - linear congruential generator 0 .. 2^32 - 1.
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* rand64 - combines several rand values to get values from the range 0 .. 2^64 - 1.
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*
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* randConstant - service function, produces a constant column with a random value.
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*
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* The time is used as the seed.
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* Note: it is reinitialized for each columns.
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* This means that the timer must be of sufficient resolution to give different values to each columns.
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*/
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DECLARE_MULTITARGET_CODE(
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struct RandImpl
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{
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/// Fill memory with random data. The memory region must be 15-bytes padded.
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static void execute(char * output, size_t size);
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};
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) // DECLARE_MULTITARGET_CODE
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template <typename RandImpl, typename ToType, typename Name>
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class FunctionRandomImpl : public IFunction
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{
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public:
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static constexpr auto name = Name::name;
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String getName() const override
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{
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return name;
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}
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bool isDeterministic() const override { return false; }
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bool isDeterministicInScopeOfQuery() const override { return false; }
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bool useDefaultImplementationForNulls() const override { return false; }
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bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
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bool isVariadic() const override { return true; }
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size_t getNumberOfArguments() const override { return 0; }
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DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
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{
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if (arguments.size() > 1)
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throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
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"Number of arguments for function {} doesn't match: passed {}, should be 0 or 1.",
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getName(), arguments.size());
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return std::make_shared<DataTypeNumber<ToType>>();
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}
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ColumnPtr executeImpl(const ColumnsWithTypeAndName &, const DataTypePtr &, size_t input_rows_count) const override
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{
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auto col_to = ColumnVector<ToType>::create();
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typename ColumnVector<ToType>::Container & vec_to = col_to->getData();
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size_t size = input_rows_count;
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vec_to.resize(size);
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RandImpl::execute(reinterpret_cast<char *>(vec_to.data()), vec_to.size() * sizeof(ToType));
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return col_to;
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}
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};
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template <typename ToType, typename Name>
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class FunctionRandom : public FunctionRandomImpl<TargetSpecific::Default::RandImpl, ToType, Name>
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{
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public:
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explicit FunctionRandom(ContextPtr context) : selector(context)
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{
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selector.registerImplementation<TargetArch::Default,
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FunctionRandomImpl<TargetSpecific::Default::RandImpl, ToType, Name>>();
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#if USE_MULTITARGET_CODE
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selector.registerImplementation<TargetArch::AVX2,
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FunctionRandomImpl<TargetSpecific::AVX2::RandImpl, ToType, Name>>();
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#endif
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}
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ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override
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{
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return selector.selectAndExecute(arguments, result_type, input_rows_count);
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}
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static FunctionPtr create(ContextPtr context)
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{
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return std::make_shared<FunctionRandom<ToType, Name>>(context);
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}
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private:
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ImplementationSelector<IFunction> selector;
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};
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}
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