String getTableDefinitionFromCreateQuery(const ASTPtr & query)
{
ASTPtr query_clone = query->clone();
ASTCreateQuery & create = typeid_cast<ASTCreateQuery &>(*query_clone.get());
/// We remove everything that is not needed for ATTACH from the query.
create.attach = true;
create.database.clear();
create.as_database.clear();
create.as_table.clear();
create.if_not_exists = false;
create.is_populate = false;
/// For views it is necessary to save the SELECT query itself, for the rest - on the contrary
if (!create.is_view && !create.is_materialized_view)
create.select = nullptr;
create.format = nullptr;
create.out_file = nullptr;
std::ostringstream statement_stream;
formatAST(create, statement_stream, false);
statement_stream << '\n';
return statement_stream.str();
}
/// Extract all subfunctions of the main conjunction, but depending only on the specified columns
static void extractFunctions(ASTPtr expression, const NameSet & columns, std::vector<ASTPtr> & result)
{
const ASTFunction * function = typeid_cast<const ASTFunction *>(&*expression);
if (function && function->name == "and")
{
for (size_t i = 0; i < function->arguments->children.size(); ++i)
extractFunctions(function->arguments->children[i], columns, result);
}
else if (isValidFunction(expression, columns))
{
result.push_back(expression->clone());
}
}
bool filterBlockWithQuery(ASTPtr query, Block & block, const Context & context)
{
query = query->clone();
const ASTSelectQuery & select = typeid_cast<ASTSelectQuery & >(*query);
if (!select.where_expression && !select.prewhere_expression)
return false;
NameSet columns;
for (const auto & it : block.getColumnsList())
columns.insert(it.name);
/// Составим выражение, вычисляющее выражения в WHERE и PREWHERE, зависящие только от имеющихся столбцов.
std::vector<ASTPtr> functions;
if (select.where_expression)
extractFunctions(select.where_expression, columns, functions);
if (select.prewhere_expression)
extractFunctions(select.prewhere_expression, columns, functions);
ASTPtr expression_ast = buildWhereExpression(functions);
if (!expression_ast)
return false;
/// Распарсим и вычислим выражение.
ExpressionAnalyzer analyzer(expression_ast, context, {}, block.getColumnsList());
ExpressionActionsPtr actions = analyzer.getActions(false);
actions->execute(block);
/// Отфильтруем блок.
String filter_column_name = expression_ast->getColumnName();
ColumnPtr filter_column = block.getByName(filter_column_name).column;
if (auto converted = filter_column->convertToFullColumnIfConst())
filter_column = converted;
const IColumn::Filter & filter = dynamic_cast<ColumnUInt8 &>(*filter_column).getData();
if (std::accumulate(filter.begin(), filter.end(), 0ul) == filter.size())
return false;
for (size_t i = 0; i < block.columns(); ++i)
{
ColumnPtr & column = block.safeGetByPosition(i).column;
column = column->filter(filter, -1);
}
return true;
}
String getTableDefinitionFromCreateQuery(const ASTPtr & query)
{
ASTPtr query_clone = query->clone();
ASTCreateQuery & create = typeid_cast<ASTCreateQuery &>(*query_clone.get());
/// Удаляем из запроса всё, что не нужно для ATTACH.
create.attach = true;
create.database.clear();
create.as_database.clear();
create.as_table.clear();
create.if_not_exists = false;
create.is_populate = false;
String engine = typeid_cast<ASTFunction &>(*create.storage).name;
/// Для engine VIEW необходимо сохранить сам селект запрос, для остальных - наоборот
if (engine != "View" && engine != "MaterializedView")
create.select = nullptr;
std::ostringstream statement_stream;
formatAST(create, statement_stream, 0, false);
statement_stream << '\n';
return statement_stream.str();
}
InterpreterSystemQuery::InterpreterSystemQuery(const ASTPtr & query_ptr_, Context & context_)
: query_ptr(query_ptr_->clone()), context(context_), log(&Poco::Logger::get("InterpreterSystemQuery")) {}
