ClickHouse/dbms/include/DB/Interpreters/InterpreterShowCreateQuery.h

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#pragma once
#include <DB/Storages/IStorage.h>
#include <DB/Parsers/TablePropertiesQueriesASTs.h>
#include <DB/Parsers/ASTIdentifier.h>
#include <DB/Parsers/formatAST.h>
#include <DB/Interpreters/Context.h>
#include <DB/DataStreams/OneBlockInputStream.h>
#include <DB/DataStreams/BlockIO.h>
#include <DB/DataStreams/copyData.h>
#include <DB/DataTypes/DataTypesNumberFixed.h>
#include <DB/DataTypes/DataTypeString.h>
namespace DB
{
/** Вернуть одну строку с одним столбцом statement типа String с текстом запроса, создающего указанную таблицу.
*/
class InterpreterShowCreateQuery
{
public:
InterpreterShowCreateQuery(ASTPtr query_ptr_, Context & context_)
: query_ptr(query_ptr_), context(context_) {}
BlockIO execute()
{
BlockIO res;
res.in = executeImpl();
res.in_sample = getSampleBlock();
return res;
}
BlockInputStreamPtr executeAndFormat(WriteBuffer & buf)
{
Block sample = getSampleBlock();
ASTPtr format_ast = dynamic_cast<ASTShowCreateQuery &>(*query_ptr).format;
String format_name = format_ast ? dynamic_cast<ASTIdentifier &>(*format_ast).name : "TabSeparated";
BlockInputStreamPtr in = executeImpl();
BlockOutputStreamPtr out = context.getFormatFactory().getOutput(format_name, buf, sample);
copyData(*in, *out);
return in;
}
private:
ASTPtr query_ptr;
Context context;
Block getSampleBlock()
{
ColumnWithNameAndType col;
col.name = "statement";
col.type = new DataTypeString;
Block block;
block.insert(col);
return block;
}
BlockInputStreamPtr executeImpl()
{
const ASTShowCreateQuery & ast = dynamic_cast<const ASTShowCreateQuery &>(*query_ptr);
String res;
{
Poco::ScopedLock<Poco::Mutex> lock(context.getMutex());
if (!context.isTableExist(ast.database, ast.table))
throw Exception("Table " + (ast.database.empty() ? "" : ast.database + ".") + ast.table + " doesn't exist", ErrorCodes::UNKNOWN_TABLE);
std::stringstream stream;
formatAST(*context.getCreateQuery(ast.database, ast.table), stream, 0, false, true);
res = stream.str();
}
ColumnWithNameAndType col;
col.name = "statement";
col.type = new DataTypeString;
col.column = new ColumnConstString(1, res);
Block block;
block.insert(col);
return new OneBlockInputStream(block);
}
};
}