ClickHouse/dbms/include/DB/Dictionaries/MongoDBBlockInputStream.h

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#pragma once
#include <DB/Core/Block.h>
#include <DB/Dictionaries/DictionaryStructure.h>
#include <DB/DataStreams/IProfilingBlockInputStream.h>
#include <DB/DataTypes/DataTypesNumberFixed.h>
#include <DB/DataTypes/DataTypeString.h>
#include <DB/DataTypes/DataTypeDate.h>
#include <DB/DataTypes/DataTypeDateTime.h>
#include <DB/Columns/ColumnString.h>
#include <ext/range.hpp>
#include <mongo/client/dbclient.h>
#include <vector>
#include <string>
#include <DB/Core/FieldVisitors.h>
namespace DB
{
/// Converts mongo::DBClientCursor to a stream of DB::Block`s
class MongoDBBlockInputStream final : public IProfilingBlockInputStream
{
enum struct value_type_t
{
UInt8,
UInt16,
UInt32,
UInt64,
Int8,
Int16,
Int32,
Int64,
Float32,
Float64,
String,
Date,
DateTime
};
public:
MongoDBBlockInputStream(
std::unique_ptr<mongo::DBClientCursor> cursor_, const Block & sample_block_, const std::size_t max_block_size)
: cursor{std::move(cursor_)}, sample_block{sample_block_}, max_block_size{max_block_size}
{
/// do nothing if cursor has no data
if (!cursor->more())
return;
const auto num_columns = sample_block.columns();
types.reserve(num_columns);
names.reserve(num_columns);
sample_columns.reserve(num_columns);
/// save types of each column to eliminate subsequent typeid_cast<> invocations
for (const auto idx : ext::range(0, num_columns))
{
const auto & column = sample_block.getByPosition(idx);
const auto type = column.type.get();
if (typeid_cast<const DataTypeUInt8 *>(type))
types.push_back(value_type_t::UInt8);
else if (typeid_cast<const DataTypeUInt16 *>(type))
types.push_back(value_type_t::UInt16);
else if (typeid_cast<const DataTypeUInt32 *>(type))
types.push_back(value_type_t::UInt32);
else if (typeid_cast<const DataTypeUInt64 *>(type))
types.push_back(value_type_t::UInt64);
else if (typeid_cast<const DataTypeInt8 *>(type))
types.push_back(value_type_t::Int8);
else if (typeid_cast<const DataTypeInt16 *>(type))
types.push_back(value_type_t::Int16);
else if (typeid_cast<const DataTypeInt32 *>(type))
types.push_back(value_type_t::Int32);
else if (typeid_cast<const DataTypeInt64 *>(type))
types.push_back(value_type_t::Int64);
else if (typeid_cast<const DataTypeFloat32 *>(type))
types.push_back(value_type_t::Float32);
else if (typeid_cast<const DataTypeInt64 *>(type))
types.push_back(value_type_t::Float64);
else if (typeid_cast<const DataTypeString *>(type))
types.push_back(value_type_t::String);
else if (typeid_cast<const DataTypeDate *>(type))
types.push_back(value_type_t::Date);
else if (typeid_cast<const DataTypeDateTime *>(type))
types.push_back(value_type_t::DateTime);
else
throw Exception{
"Unsupported type " + type->getName(),
ErrorCodes::UNKNOWN_TYPE
};
names.emplace_back(column.name);
sample_columns.emplace_back(column.column.get());
}
}
String getName() const override { return "MongoDB"; }
String getID() const override
{
using stream = std::ostringstream;
return "MongoDB(@" + static_cast<stream &>(stream{} << cursor.get()).str() + ")";
}
private:
Block readImpl() override
{
/// return an empty block if cursor has no data
if (!cursor->more())
return {};
auto block = sample_block.cloneEmpty();
/// cache pointers returned by the calls to getByPosition
std::vector<IColumn *> columns(block.columns());
const auto size = columns.size();
for (const auto i : ext::range(0, size))
columns[i] = block.getByPosition(i).column.get();
std::size_t num_rows = 0;
while (cursor->more())
{
const auto row = cursor->next();
for (const auto idx : ext::range(0, size))
{
const auto value = row[names[idx]];
if (value.ok())
insertValue(columns[idx], types[idx], value);
else
insertDefaultValue(columns[idx], *sample_columns[idx]);
}
++num_rows;
if (num_rows == max_block_size)
break;
}
return block;
}
static void insertValue(IColumn * const column, const value_type_t type, const mongo::BSONElement & value)
{
switch (type)
{
case value_type_t::UInt8:
{
if (value.type() != mongo::Bool)
throw Exception{
"Type mismatch, expected Bool, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnFloat64 *>(column)->insert(value.boolean());
break;
}
case value_type_t::UInt16:
{
if (!value.isNumber())
throw Exception{
"Type mismatch, expected a number, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnUInt16 *>(column)->insert(value.numberInt());
break;
}
case value_type_t::UInt32:
{
if (!value.isNumber())
throw Exception{
"Type mismatch, expected a number, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnUInt32 *>(column)->insert(value.numberInt());
break;
}
case value_type_t::UInt64:
{
if (!value.isNumber())
throw Exception{
"Type mismatch, expected a number, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnUInt64 *>(column)->insert(value.numberLong());
break;
}
case value_type_t::Int8:
{
if (!value.isNumber())
throw Exception{
"Type mismatch, expected a number, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnInt8 *>(column)->insert(value.numberInt());
break;
}
case value_type_t::Int16:
{
if (!value.isNumber())
throw Exception{
"Type mismatch, expected a number, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnInt16 *>(column)->insert(value.numberInt());
break;
}
case value_type_t::Int32:
{
if (!value.isNumber())
throw Exception{
"Type mismatch, expected a number, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnInt32 *>(column)->insert(value.numberInt());
break;
}
case value_type_t::Int64:
{
if (!value.isNumber())
throw Exception{
"Type mismatch, expected a number, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnInt64 *>(column)->insert(value.numberLong());
break;
}
case value_type_t::Float32:
{
if (!value.isNumber())
throw Exception{
"Type mismatch, expected a number, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnFloat32 *>(column)->insert(value.number());
break;
}
case value_type_t::Float64:
{
if (!value.isNumber())
throw Exception{
"Type mismatch, expected a number, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnFloat64 *>(column)->insert(value.number());
break;
}
case value_type_t::String:
{
if (value.type() != mongo::String)
throw Exception{
"Type mismatch, expected String, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
const auto string = value.String();
static_cast<ColumnString *>(column)->insertDataWithTerminatingZero(string.data(), string.size() + 1);
break;
}
case value_type_t::Date:
{
if (value.type() != mongo::Date)
throw Exception{
"Type mismatch, expected Date, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnUInt16 *>(column)->insert(
UInt16{DateLUT::instance().toDayNum(value.date().toTimeT())});
break;
}
case value_type_t::DateTime:
{
if (value.type() != mongo::Date)
throw Exception{
"Type mismatch, expected Date, got " + std::string{mongo::typeName(value.type())},
ErrorCodes::TYPE_MISMATCH
};
static_cast<ColumnUInt32 *>(column)->insert(value.date().toTimeT());
break;
}
}
}
static void insertDefaultValue(IColumn * const column, const IColumn & sample_column)
{
column->insertFrom(sample_column, 0);
}
std::unique_ptr<mongo::DBClientCursor> cursor;
Block sample_block;
const std::size_t max_block_size;
std::vector<value_type_t> types;
std::vector<mongo::StringData> names;
std::vector<const IColumn *> sample_columns;
};
}