ClickHouse/src/TableFunctions/ITableFunction.cpp

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#include <TableFunctions/ITableFunction.h>
#include <Interpreters/Context.h>
#include <Storages/StorageFactory.h>
#include <Storages/StorageTableFunction.h>
#include <Access/AccessFlags.h>
#include <Common/ProfileEvents.h>
namespace ProfileEvents
{
extern const Event TableFunctionExecute;
}
namespace DB
{
StoragePtr ITableFunction::execute(const ASTPtr & ast_function, const Context & context, const std::string & table_name,
ColumnsDescription cached_columns) const
{
ProfileEvents::increment(ProfileEvents::TableFunctionExecute);
context.checkAccess(AccessType::CREATE_TEMPORARY_TABLE | StorageFactory::instance().getSourceAccessType(getStorageTypeName()));
if (cached_columns.empty() || (hasStaticStructure() && cached_columns == getActualTableStructure(context)))
return executeImpl(ast_function, context, table_name, std::move(cached_columns));
auto get_storage = [=, tf = shared_from_this()]() -> StoragePtr
{
return tf->executeImpl(ast_function, context, table_name, cached_columns);
};
/// It will request actual table structure and create underlying storage lazily
return std::make_shared<StorageTableFunctionProxy>(StorageID(getDatabaseName(), table_name), std::move(get_storage),
std::move(cached_columns), needStructureConversion());
}
}