ASTPtr InterpreterCreateQuery::formatColumns(NamesAndTypesList columns,
const NamesAndTypesList & materialized_columns,
const NamesAndTypesList & alias_columns,
const ColumnDefaults & column_defaults)
{
columns.insert(std::end(columns), std::begin(materialized_columns), std::end(materialized_columns));
columns.insert(std::end(columns), std::begin(alias_columns), std::end(alias_columns));
auto columns_list = std::make_shared<ASTExpressionList>();
for (const auto & column : columns)
{
const auto column_declaration = std::make_shared<ASTColumnDeclaration>();
ASTPtr column_declaration_ptr{column_declaration};
column_declaration->name = column.name;
StringPtr type_name = std::make_shared<String>(column.type->getName());
auto pos = type_name->data();
const auto end = pos + type_name->size();
ParserIdentifierWithOptionalParameters storage_p;
column_declaration->type = parseQuery(storage_p, pos, end, "data type");
column_declaration->type->query_string = type_name;
const auto it = column_defaults.find(column.name);
if (it != std::end(column_defaults))
{
column_declaration->default_specifier = toString(it->second.type);
column_declaration->default_expression = it->second.expression->clone();
}
columns_list->children.push_back(column_declaration_ptr);
}
return columns_list;
}
BlockInputStreams StorageSystemColumns::read(
const Names & column_names,
ASTPtr query,
const Context & context,
const Settings & settings,
QueryProcessingStage::Enum & processed_stage,
const size_t max_block_size,
const unsigned threads)
{
check(column_names);
processed_stage = QueryProcessingStage::FetchColumns;
Block block;
std::map<std::pair<std::string, std::string>, StoragePtr> storages;
{
Databases databases = context.getDatabases();
/// Добавляем столбец database.
ColumnPtr database_column = std::make_shared<ColumnString>();
for (const auto & database : databases)
database_column->insert(database.first);
block.insert(ColumnWithTypeAndName(database_column, std::make_shared<DataTypeString>(), "database"));
/// Отфильтруем блок со столбцом database.
VirtualColumnUtils::filterBlockWithQuery(query, block, context);
if (!block.rows())
return BlockInputStreams();
database_column = block.getByName("database").column;
size_t rows = database_column->size();
/// Добавляем столбец table.
ColumnPtr table_column = std::make_shared<ColumnString>();
IColumn::Offsets_t offsets(rows);
for (size_t i = 0; i < rows; ++i)
{
const std::string database_name = (*database_column)[i].get<std::string>();
const DatabasePtr database = databases.at(database_name);
offsets[i] = i ? offsets[i - 1] : 0;
for (auto iterator = database->getIterator(); iterator->isValid(); iterator->next())
{
const String & table_name = iterator->name();
storages.emplace(std::piecewise_construct,
std::forward_as_tuple(database_name, table_name),
std::forward_as_tuple(iterator->table()));
table_column->insert(table_name);
offsets[i] += 1;
}
}
for (size_t i = 0; i < block.columns(); ++i)
{
ColumnPtr & column = block.getByPosition(i).column;
column = column->replicate(offsets);
}
block.insert(ColumnWithTypeAndName(table_column, std::make_shared<DataTypeString>(), "table"));
}
/// Отфильтруем блок со столбцами database и table.
VirtualColumnUtils::filterBlockWithQuery(query, block, context);
if (!block.rows())
return BlockInputStreams();
ColumnPtr filtered_database_column = block.getByName("database").column;
ColumnPtr filtered_table_column = block.getByName("table").column;
/// Составляем результат.
ColumnPtr database_column = std::make_shared<ColumnString>();
ColumnPtr table_column = std::make_shared<ColumnString>();
ColumnPtr name_column = std::make_shared<ColumnString>();
ColumnPtr type_column = std::make_shared<ColumnString>();
ColumnPtr default_type_column = std::make_shared<ColumnString>();
ColumnPtr default_expression_column = std::make_shared<ColumnString>();
ColumnPtr bytes_column = std::make_shared<ColumnUInt64>();
size_t rows = filtered_database_column->size();
for (size_t i = 0; i < rows; ++i)
{
const std::string database_name = (*filtered_database_column)[i].get<std::string>();
const std::string table_name = (*filtered_table_column)[i].get<std::string>();
NamesAndTypesList columns;
ColumnDefaults column_defaults;
std::unordered_map<String, size_t> column_sizes;
{
StoragePtr storage = storages.at(std::make_pair(database_name, table_name));
IStorage::TableStructureReadLockPtr table_lock;
try
{
table_lock = storage->lockStructure(false);
}
catch (const Exception & e)
{
/** There are case when IStorage::drop was called,
* but we still own the object.
* Then table will throw exception at attempt to lock it.
* Just skip the table.
*/
if (e.code() == ErrorCodes::TABLE_IS_DROPPED)
continue;
else
throw;
}
columns = storage->getColumnsList();
columns.insert(std::end(columns), std::begin(storage->alias_columns), std::end(storage->alias_columns));
column_defaults = storage->column_defaults;
/** Данные о размерах столбцов для таблиц семейства MergeTree.
* NOTE: В дальнейшем можно сделать интерфейс, позволяющий получить размеры столбцов у IStorage.
*/
if (auto storage_concrete = dynamic_cast<StorageMergeTree *>(storage.get()))
{
column_sizes = storage_concrete->getData().getColumnSizes();
}
else if (auto storage_concrete = dynamic_cast<StorageReplicatedMergeTree *>(storage.get()))
{
column_sizes = storage_concrete->getData().getColumnSizes();
auto unreplicated_data = storage_concrete->getUnreplicatedData();
if (unreplicated_data)
{
auto unreplicated_column_sizes = unreplicated_data->getColumnSizes();
for (const auto & name_size : unreplicated_column_sizes)
column_sizes[name_size.first] += name_size.second;
}
}
}
for (const auto & column : columns)
{
database_column->insert(database_name);
table_column->insert(table_name);
name_column->insert(column.name);
type_column->insert(column.type->getName());
{
const auto it = column_defaults.find(column.name);
if (it == std::end(column_defaults))
{
default_type_column->insertDefault();
default_expression_column->insertDefault();
}
else
{
default_type_column->insert(toString(it->second.type));
default_expression_column->insert(queryToString(it->second.expression));
}
}
{
const auto it = column_sizes.find(column.name);
if (it == std::end(column_sizes))
bytes_column->insertDefault();
else
bytes_column->insert(it->second);
}
}
}
block.clear();
block.insert(ColumnWithTypeAndName(database_column, std::make_shared<DataTypeString>(), "database"));
block.insert(ColumnWithTypeAndName(table_column, std::make_shared<DataTypeString>(), "table"));
block.insert(ColumnWithTypeAndName(name_column, std::make_shared<DataTypeString>(), "name"));
block.insert(ColumnWithTypeAndName(type_column, std::make_shared<DataTypeString>(), "type"));
block.insert(ColumnWithTypeAndName(default_type_column, std::make_shared<DataTypeString>(), "default_type"));
block.insert(ColumnWithTypeAndName(default_expression_column, std::make_shared<DataTypeString>(), "default_expression"));
block.insert(ColumnWithTypeAndName(bytes_column, std::make_shared<DataTypeUInt64>(), "bytes"));
return BlockInputStreams{ 1, std::make_shared<OneBlockInputStream>(block) };
}