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84 lines
2.5 KiB
C++
84 lines
2.5 KiB
C++
#include <iostream>
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#include <iomanip>
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#include <IO/WriteBufferFromOStream.h>
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#include <IO/ReadHelpers.h>
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#include <Storages/System/StorageSystemNumbers.h>
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#include <DataStreams/LimitBlockInputStream.h>
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#include <DataStreams/ExpressionBlockInputStream.h>
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#include <Formats/FormatFactory.h>
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#include <DataStreams/copyData.h>
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#include <DataTypes/DataTypesNumber.h>
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#include <Parsers/ParserSelectQuery.h>
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#include <Parsers/parseQuery.h>
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#include <Interpreters/SyntaxAnalyzer.h>
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#include <Interpreters/ExpressionAnalyzer.h>
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#include <Interpreters/ExpressionActions.h>
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#include <Interpreters/Context.h>
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int main(int argc, char ** argv)
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try
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{
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using namespace DB;
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size_t n = argc == 2 ? parse<UInt64>(argv[1]) : 10ULL;
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std::string input = "SELECT number, number / 3, number * number";
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ParserSelectQuery parser;
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ASTPtr ast = parseQuery(parser, input.data(), input.data() + input.size(), "", 0);
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Context context = Context::createGlobal();
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NamesAndTypesList source_columns = {{"number", std::make_shared<DataTypeUInt64>()}};
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auto syntax_result = SyntaxAnalyzer(context, {}).analyze(ast, source_columns);
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ExpressionAnalyzer analyzer(ast, syntax_result, context);
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ExpressionActionsChain chain(context);
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analyzer.appendSelect(chain, false);
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analyzer.appendProjectResult(chain);
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chain.finalize();
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ExpressionActionsPtr expression = chain.getLastActions();
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StoragePtr table = StorageSystemNumbers::create("numbers", false);
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Names column_names;
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column_names.push_back("number");
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QueryProcessingStage::Enum stage = table->getQueryProcessingStage(context);
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BlockInputStreamPtr in;
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in = table->read(column_names, {}, context, stage, 8192, 1)[0];
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in = std::make_shared<ExpressionBlockInputStream>(in, expression);
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in = std::make_shared<LimitBlockInputStream>(in, 10, std::max(static_cast<Int64>(0), static_cast<Int64>(n) - 10));
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WriteBufferFromOStream out1(std::cout);
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BlockOutputStreamPtr out = FormatFactory::instance().getOutput("TabSeparated", out1, expression->getSampleBlock(), context);
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{
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Stopwatch stopwatch;
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stopwatch.start();
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copyData(*in, *out);
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stopwatch.stop();
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std::cout << std::fixed << std::setprecision(2)
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<< "Elapsed " << stopwatch.elapsedSeconds() << " sec."
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<< ", " << n / stopwatch.elapsedSeconds() << " rows/sec."
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<< std::endl;
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}
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return 0;
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}
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catch (const DB::Exception & e)
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{
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std::cerr << e.what() << ", " << e.displayText() << std::endl;
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throw;
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}
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