mirror of
https://github.com/ClickHouse/ClickHouse.git
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136 lines
4.3 KiB
C++
136 lines
4.3 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 <Poco/Data/Session.h>
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#include <Poco/Data/Statement.h>
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#include <Poco/Data/RecordSet.h>
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#include <ext/range.hpp>
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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 query to ODBC source as a sequence of Blocks, simplifies chaining
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class ODBCBlockInputStream final : public IProfilingBlockInputStream
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{
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public:
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ODBCBlockInputStream(
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Poco::Data::Session && session, const std::string & query_str, const Block & sample_block,
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const std::size_t max_block_size)
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:
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session{session},
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statement{(this->session << query_str, Poco::Data::Keywords::now)},
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result{statement},
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iterator{result.begin()},
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max_block_size{max_block_size}
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{
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if (sample_block.columns() != result.columnCount())
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throw Exception{
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"RecordSet contains " + toString(result.columnCount()) + " 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 "ODBC"; }
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String getID() const override
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{
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return "ODBC(" + statement.toString() + ")";
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}
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private:
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using value_type_t = ExternalResultDescription::value_type_t;
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Block readImpl() override
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{
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if (iterator == result.end())
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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 (iterator != result.end())
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{
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Poco::Data::Row & row = *iterator;
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for (const auto idx : ext::range(0, row.fieldCount()))
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{
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const Poco::Dynamic::Var & value = row[idx];
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if (!value.isEmpty())
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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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++iterator;
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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 value_type_t type, const Poco::Dynamic::Var & value)
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{
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switch (type)
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{
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case value_type_t::UInt8: static_cast<ColumnUInt8 *>(column)->insert(value.convert<UInt64>()); break;
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case value_type_t::UInt16: static_cast<ColumnUInt16 *>(column)->insert(value.convert<UInt64>()); break;
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case value_type_t::UInt32: static_cast<ColumnUInt32 *>(column)->insert(value.convert<UInt64>()); break;
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case value_type_t::UInt64: static_cast<ColumnUInt64 *>(column)->insert(value.convert<UInt64>()); break;
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case value_type_t::Int8: static_cast<ColumnInt8 *>(column)->insert(value.convert<Int64>()); break;
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case value_type_t::Int16: static_cast<ColumnInt16 *>(column)->insert(value.convert<Int64>()); break;
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case value_type_t::Int32: static_cast<ColumnInt32 *>(column)->insert(value.convert<Int64>()); break;
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case value_type_t::Int64: static_cast<ColumnInt64 *>(column)->insert(value.convert<Int64>()); break;
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case value_type_t::Float32: static_cast<ColumnFloat32 *>(column)->insert(value.convert<Float64>()); break;
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case value_type_t::Float64: static_cast<ColumnFloat64 *>(column)->insert(value.convert<Float64>()); break;
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case value_type_t::String: static_cast<ColumnString *>(column)->insert(value.convert<String>()); break;
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case value_type_t::Date: static_cast<ColumnUInt16 *>(column)->insert(UInt16{LocalDate{value.convert<String>()}.getDayNum()}); break;
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case value_type_t::DateTime: static_cast<ColumnUInt32 *>(column)->insert(time_t{LocalDateTime{value.convert<String>()}}); 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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Poco::Data::Session session;
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Poco::Data::Statement statement;
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Poco::Data::RecordSet result;
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Poco::Data::RecordSet::Iterator iterator;
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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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