ClickHouse/programs/odbc-bridge/ODBCBlockInputStream.h

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#pragma once
#include <string>
#include <Core/Block.h>
#include <DataStreams/IBlockInputStream.h>
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#include <Core/ExternalResultDescription.h>
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#include <nanodbc/nanodbc.h>
namespace DB
{
/// Allows processing results of a query to ODBC source as a sequence of Blocks, simplifies chaining
class ODBCBlockInputStream final : public IBlockInputStream
{
public:
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ODBCBlockInputStream(nanodbc::connection & connection_, const std::string & query_str, const Block & sample_block, const UInt64 max_block_size_);
String getName() const override { return "ODBC"; }
Block getHeader() const override { return description.sample_block.cloneEmpty(); }
private:
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using QueryResult = std::shared_ptr<nanodbc::result>;
using ValueType = ExternalResultDescription::ValueType;
Block readImpl() override;
static void insertValue(IColumn & column, const DataTypePtr data_type, const ValueType type, nanodbc::result & row, size_t idx);
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static void insertDefaultValue(IColumn & column, const IColumn & sample_column)
{
column.insertFrom(sample_column, 0);
}
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Poco::Logger * log;
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const UInt64 max_block_size;
ExternalResultDescription description;
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nanodbc::connection & connection;
nanodbc::result result;
String query;
bool finished = false;
};
}