ClickHouse/dbms/include/DB/Dictionaries/MySQLBlockInputStream.h
Andrey Mironov 168e1cd98d dbms: post-review corrections [#METR-13298]
add dummy CacheDictionary (could not commit without it)
2015-02-10 17:50:52 +03:00

116 lines
3.9 KiB
C++

#pragma once
#include <DB/Core/Block.h>
#include <DB/DataStreams/IProfilingBlockInputStream.h>
#include <DB/DataTypes/DataTypesNumberFixed.h>
#include <DB/DataTypes/DataTypeString.h>
#include <statdaemons/ext/range.hpp>
#include <mysqlxx/Query.h>
#include <vector>
#include <string>
namespace DB
{
/// Allows processing results of a MySQL query as a sequence of Blocks, simplifies chaining
class MySQLBlockInputStream final : public IProfilingBlockInputStream
{
public:
MySQLBlockInputStream(mysqlxx::Query query, const Block & sample_block, const std::size_t max_block_size)
: query{std::move(query)}, result{query.use()}, sample_block{sample_block}, max_block_size{max_block_size}
{
types.reserve(sample_block.columns());
for (const auto idx : ext::range(0, sample_block.columns()))
{
const auto type = sample_block.getByPosition(idx).type.get();
if (typeid_cast<const DataTypeUInt8 *>(type))
types.push_back(AttributeType::uint8);
else if (typeid_cast<const DataTypeUInt16 *>(type))
types.push_back(AttributeType::uint16);
else if (typeid_cast<const DataTypeUInt32 *>(type))
types.push_back(AttributeType::uint32);
else if (typeid_cast<const DataTypeUInt64 *>(type))
types.push_back(AttributeType::uint64);
else if (typeid_cast<const DataTypeInt8 *>(type))
types.push_back(AttributeType::int8);
else if (typeid_cast<const DataTypeInt16 *>(type))
types.push_back(AttributeType::int16);
else if (typeid_cast<const DataTypeInt32 *>(type))
types.push_back(AttributeType::int32);
else if (typeid_cast<const DataTypeInt64 *>(type))
types.push_back(AttributeType::int64);
else if (typeid_cast<const DataTypeFloat32 *>(type))
types.push_back(AttributeType::float32);
else if (typeid_cast<const DataTypeInt64 *>(type))
types.push_back(AttributeType::float64);
else if (typeid_cast<const DataTypeString *>(type))
types.push_back(AttributeType::string);
else
throw Exception{
"Unsupported type " + type->getName(),
ErrorCodes::UNKNOWN_TYPE
};
}
}
String getName() const override { return "MySQLBlockInputStream"; }
String getID() const override
{
return "MySQL(" + query.str() + ")";
}
private:
Block readImpl() override
{
auto block = sample_block.cloneEmpty();
if (block.columns() != result.getNumFields())
throw Exception{
"mysqlxx::UseQueryResult contains " + toString(result.getNumFields()) + " columns while " +
toString(block.columns()) + " expected",
ErrorCodes::NUMBER_OF_COLUMNS_DOESNT_MATCH
};
std::size_t rows = 0;
while (auto row = result.fetch())
{
for (const auto idx : ext::range(0, row.size()))
insertValue(block.getByPosition(idx).column, row[idx], types[idx]);
++rows;
if (rows == max_block_size)
break;
}
return rows == 0 ? Block{} : block;
};
static void insertValue(ColumnPtr & column, const mysqlxx::Value & value, const AttributeType type)
{
switch (type)
{
case AttributeType::uint8: column->insert(static_cast<UInt64>(value)); break;
case AttributeType::uint16: column->insert(static_cast<UInt64>(value)); break;
case AttributeType::uint32: column->insert(static_cast<UInt64>(value)); break;
case AttributeType::uint64: column->insert(static_cast<UInt64>(value)); break;
case AttributeType::int8: column->insert(static_cast<Int64>(value)); break;
case AttributeType::int16: column->insert(static_cast<Int64>(value)); break;
case AttributeType::int32: column->insert(static_cast<Int64>(value)); break;
case AttributeType::int64: column->insert(static_cast<Int64>(value)); break;
case AttributeType::float32: column->insert(static_cast<Float64>(value)); break;
case AttributeType::float64: column->insert(static_cast<Float64>(value)); break;
case AttributeType::string: column->insert(value.getString()); break;
}
}
mysqlxx::Query query;
mysqlxx::UseQueryResult result;
Block sample_block;
const std::size_t max_block_size;
std::vector<AttributeType> types;
};
}