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122 lines
4.0 KiB
C++
122 lines
4.0 KiB
C++
#pragma once
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#include <DB/Core/Block.h>
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#include <DB/DataStreams/IProfilingBlockInputStream.h>
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#include <DB/DataTypes/DataTypesNumberFixed.h>
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#include <DB/DataTypes/DataTypeString.h>
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#include <DB/DataTypes/DataTypeDate.h>
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#include <DB/DataTypes/DataTypeDateTime.h>
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#include <DB/Columns/ColumnString.h>
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#include <DB/Dictionaries/ExternalResultDescription.h>
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#include <ext/range.hpp>
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#include <mysqlxx/Query.h>
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#include <mysqlxx/PoolWithFailover.h>
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#include <vector>
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#include <string>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int NUMBER_OF_COLUMNS_DOESNT_MATCH;
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}
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/// Allows processing results of a MySQL query as a sequence of Blocks, simplifies chaining
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class MySQLBlockInputStream final : public IProfilingBlockInputStream
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{
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public:
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MySQLBlockInputStream(
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const mysqlxx::PoolWithFailover::Entry & entry, const std::string & query_str, const Block & sample_block,
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const std::size_t max_block_size)
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: entry{entry}, query{this->entry->query(query_str)}, result{query.use()},
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max_block_size{max_block_size}
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{
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if (sample_block.columns() != result.getNumFields())
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throw Exception{
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"mysqlxx::UseQueryResult contains " + toString(result.getNumFields()) + " columns while " +
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toString(sample_block.columns()) + " expected",
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ErrorCodes::NUMBER_OF_COLUMNS_DOESNT_MATCH};
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description.init(sample_block);
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}
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String getName() const override { return "MySQL"; }
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String getID() const override
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{
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return "MySQL(" + query.str() + ")";
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}
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private:
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using ValueType = ExternalResultDescription::ValueType;
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Block readImpl() override
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{
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auto row = result.fetch();
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if (!row)
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return {};
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auto block = description.sample_block.cloneEmpty();
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/// cache pointers returned by the calls to getByPosition
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std::vector<IColumn *> columns(block.columns());
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for (const auto i : ext::range(0, columns.size()))
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columns[i] = block.getByPosition(i).column.get();
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std::size_t num_rows = 0;
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while (row)
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{
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for (const auto idx : ext::range(0, row.size()))
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{
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const auto value = row[idx];
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if (!value.isNull())
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insertValue(columns[idx], description.types[idx], value);
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else
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insertDefaultValue(columns[idx], *description.sample_columns[idx]);
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}
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++num_rows;
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if (num_rows == max_block_size)
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break;
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row = result.fetch();
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}
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return block;
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}
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static void insertValue(IColumn * const column, const ValueType type, const mysqlxx::Value & value)
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{
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switch (type)
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{
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case ValueType::UInt8: static_cast<ColumnUInt8 *>(column)->insert(value.getUInt()); break;
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case ValueType::UInt16: static_cast<ColumnUInt16 *>(column)->insert(value.getUInt()); break;
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case ValueType::UInt32: static_cast<ColumnUInt32 *>(column)->insert(value.getUInt()); break;
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case ValueType::UInt64: static_cast<ColumnUInt64 *>(column)->insert(value.getUInt()); break;
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case ValueType::Int8: static_cast<ColumnInt8 *>(column)->insert(value.getInt()); break;
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case ValueType::Int16: static_cast<ColumnInt16 *>(column)->insert(value.getInt()); break;
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case ValueType::Int32: static_cast<ColumnInt32 *>(column)->insert(value.getInt()); break;
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case ValueType::Int64: static_cast<ColumnInt64 *>(column)->insert(value.getInt()); break;
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case ValueType::Float32: static_cast<ColumnFloat32 *>(column)->insert(value.getDouble()); break;
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case ValueType::Float64: static_cast<ColumnFloat64 *>(column)->insert(value.getDouble()); break;
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case ValueType::String: static_cast<ColumnString *>(column)->insertData(value.data(), value.size()); break;
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case ValueType::Date: static_cast<ColumnUInt16 *>(column)->insert(UInt16{value.getDate().getDayNum()}); break;
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case ValueType::DateTime: static_cast<ColumnUInt32 *>(column)->insert(time_t{value.getDateTime()}); break;
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}
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}
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static void insertDefaultValue(IColumn * const column, const IColumn & sample_column)
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{
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column->insertFrom(sample_column, 0);
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}
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mysqlxx::PoolWithFailover::Entry entry;
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mysqlxx::Query query;
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mysqlxx::UseQueryResult result;
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const std::size_t max_block_size;
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ExternalResultDescription description;
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};
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}
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