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

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#pragma once
#include <DB/Core/Block.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>
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#include <ext/range.hpp>
#include <mysqlxx/Query.h>
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#include <mysqlxx/PoolWithFailover.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
{
enum struct value_type_t
{
UInt8,
UInt16,
UInt32,
UInt64,
Int8,
Int16,
Int32,
Int64,
Float32,
Float64,
String,
Date,
DateTime
};
public:
MySQLBlockInputStream(
const mysqlxx::PoolWithFailover::Entry & entry, const std::string & query_str, const Block & sample_block_,
const std::size_t max_block_size)
: entry{entry}, query{this->entry->query(query_str)}, result{query.use()},
sample_block{sample_block_}, max_block_size{max_block_size}
{
if (sample_block.columns() != result.getNumFields())
throw Exception{
"mysqlxx::UseQueryResult contains " + toString(result.getNumFields()) + " columns while " +
toString(sample_block.columns()) + " expected",
ErrorCodes::NUMBER_OF_COLUMNS_DOESNT_MATCH
};
const auto num_columns = sample_block.columns();
types.reserve(num_columns);
sample_columns.reserve(num_columns);
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
};
sample_columns.emplace_back(column.column.get());
}
}
String getName() const override { return "MySQL"; }
String getID() const override
{
return "MySQL(" + query.str() + ")";
}
private:
Block readImpl() override
{
auto row = result.fetch();
if (!row)
return {};
auto block = sample_block.cloneEmpty();
/// cache pointers returned by the calls to getByPosition
std::vector<IColumn *> columns(block.columns());
for (const auto i : ext::range(0, columns.size()))
columns[i] = block.getByPosition(i).column.get();
std::size_t num_rows = 0;
while (row)
{
for (const auto idx : ext::range(0, row.size()))
{
const auto value = row[idx];
if (!value.isNull())
insertValue(columns[idx], types[idx], value);
else
insertDefaultValue(columns[idx], *sample_columns[idx]);
}
++num_rows;
if (num_rows == max_block_size)
break;
row = result.fetch();
}
return block;
}
static void insertValue(IColumn * const column, const value_type_t type, const mysqlxx::Value & value)
{
switch (type)
{
case value_type_t::UInt8: static_cast<ColumnUInt8 *>(column)->insert(value.getUInt()); break;
case value_type_t::UInt16: static_cast<ColumnUInt16 *>(column)->insert(value.getUInt()); break;
case value_type_t::UInt32: static_cast<ColumnUInt32 *>(column)->insert(value.getUInt()); break;
case value_type_t::UInt64: static_cast<ColumnUInt64 *>(column)->insert(value.getUInt()); break;
case value_type_t::Int8: static_cast<ColumnInt8 *>(column)->insert(value.getInt()); break;
case value_type_t::Int16: static_cast<ColumnInt16 *>(column)->insert(value.getInt()); break;
case value_type_t::Int32: static_cast<ColumnInt32 *>(column)->insert(value.getInt()); break;
case value_type_t::Int64: static_cast<ColumnInt64 *>(column)->insert(value.getInt()); break;
case value_type_t::Float32: static_cast<ColumnFloat32 *>(column)->insert(value.getDouble()); break;
case value_type_t::Float64: static_cast<ColumnFloat64 *>(column)->insert(value.getDouble()); break;
case value_type_t::String:
{
const auto string = value.getString();
static_cast<ColumnString *>(column)->insertDataWithTerminatingZero(string.data(), string.size() + 1);
break;
}
case value_type_t::Date: static_cast<ColumnUInt16 *>(column)->insert(UInt16{value.getDate().getDayNum()}); break;
case value_type_t::DateTime: static_cast<ColumnUInt32 *>(column)->insert(time_t{value.getDateTime()}); break;
}
}
static void insertDefaultValue(IColumn * const column, const IColumn & sample_column)
{
column->insertFrom(sample_column, 0);
}
mysqlxx::PoolWithFailover::Entry entry;
mysqlxx::Query query;
mysqlxx::UseQueryResult result;
Block sample_block;
const std::size_t max_block_size;
std::vector<value_type_t> types;
std::vector<const IColumn *> sample_columns;
};
}