ClickHouse/dbms/src/Functions/dumpColumnStructure.cpp

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#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypeString.h>
namespace DB
{
/// Dump the structure of type and column.
class FunctionDumpColumnStructure : public IFunction
{
public:
static constexpr auto name = "dumpColumnStructure";
static FunctionPtr create(const Context &)
{
return std::make_shared<FunctionDumpColumnStructure>();
}
String getName() const override
{
return name;
}
bool useDefaultImplementationForNulls() const override { return false; }
size_t getNumberOfArguments() const override
{
return 1;
}
DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override
{
return std::make_shared<DataTypeString>();
}
void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) override
{
const auto & elem = block.getByPosition(arguments[0]);
/// Note that the result is not a constant, because it contains block size.
block.getByPosition(result).column
= DataTypeString().createColumnConst(input_rows_count,
elem.type->getName() + ", " + elem.column->dumpStructure())->convertToFullColumnIfConst();
}
};
void registerFunctionDumpColumnStructure(FunctionFactory & factory)
{
factory.registerFunction<FunctionDumpColumnStructure>();
}
}