ClickHouse/dbms/src/Functions/blockNumber.cpp

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#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypesNumber.h>
#include <Columns/ColumnsNumber.h>
#include <atomic>
namespace DB
{
/** Incremental block number among calls of this function. */
class FunctionBlockNumber : public IFunction
{
private:
std::atomic<size_t> block_number{0};
public:
static constexpr auto name = "blockNumber";
static FunctionPtr create(const Context &)
{
return std::make_shared<FunctionBlockNumber>();
}
/// Get the function name.
String getName() const override
{
return name;
}
bool isStateful() const override
{
return true;
}
size_t getNumberOfArguments() const override
{
return 0;
}
bool isDeterministic() const override { return false; }
bool isDeterministicInScopeOfQuery() const override
{
return false;
}
DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override
{
return std::make_shared<DataTypeUInt64>();
}
void executeImpl(Block & block, const ColumnNumbers &, size_t result, size_t input_rows_count) override
{
size_t current_block_number = block_number++;
block.getByPosition(result).column = ColumnUInt64::create(input_rows_count, current_block_number);
}
};
void registerFunctionBlockNumber(FunctionFactory & factory)
{
factory.registerFunction<FunctionBlockNumber>();
}
}