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354 lines
13 KiB
C++
354 lines
13 KiB
C++
#include <DB/Storages/AlterCommands.h>
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#include <DB/Storages/IStorage.h>
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#include <DB/DataTypes/DataTypesNumberFixed.h>
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#include <DB/DataTypes/DataTypeNested.h>
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#include <DB/Interpreters/Context.h>
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#include <DB/Interpreters/ExpressionAnalyzer.h>
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#include <DB/Interpreters/ExpressionActions.h>
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#include <DB/Parsers/ASTIdentifier.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int ILLEGAL_COLUMN;
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extern const int LOGICAL_ERROR;
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}
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void AlterCommand::apply(
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NamesAndTypesList & columns, NamesAndTypesList & materialized_columns, NamesAndTypesList & alias_columns,
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ColumnDefaults & column_defaults) const
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{
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if (type == ADD_COLUMN)
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{
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const auto exists_in = [this] (const NamesAndTypesList & columns) {
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return columns.end() != std::find_if(columns.begin(), columns.end(),
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std::bind(namesEqual, std::cref(column_name), std::placeholders::_1));
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};
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if (exists_in(columns) ||
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exists_in(materialized_columns) ||
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exists_in(alias_columns))
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{
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throw Exception{
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"Cannot add column " + column_name + ": column with this name already exists",
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DB::ErrorCodes::ILLEGAL_COLUMN
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};
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}
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const auto add_column = [this] (NamesAndTypesList & columns)
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{
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auto insert_it = columns.end();
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if (!after_column.empty())
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{
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/// Пытаемся найти первую с конца колонку с именем column_name или с именем, начинающимся с column_name и ".".
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/// Например "fruits.bananas"
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/// одинаковыми считаются имена, если они совпадают целиком или name_without_dot совпадает с частью имени до точки
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const auto reverse_insert_it = std::find_if(columns.rbegin(), columns.rend(),
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std::bind(namesEqual, std::cref(after_column), std::placeholders::_1));
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if (reverse_insert_it == columns.rend())
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throw Exception("Wrong column name. Cannot find column " + after_column + " to insert after",
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DB::ErrorCodes::ILLEGAL_COLUMN);
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else
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{
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/// base возвращает итератор, уже смещенный на один элемент вправо
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insert_it = reverse_insert_it.base();
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}
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}
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columns.emplace(insert_it, column_name, data_type);
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};
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if (default_type == ColumnDefaultType::Default)
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add_column(columns);
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else if (default_type == ColumnDefaultType::Materialized)
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add_column(materialized_columns);
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else if (default_type == ColumnDefaultType::Alias)
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add_column(alias_columns);
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else
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throw Exception{"Unknown ColumnDefaultType value", ErrorCodes::LOGICAL_ERROR};
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if (default_expression)
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column_defaults.emplace(column_name, ColumnDefault{default_type, default_expression});
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/// Медленно, так как каждый раз копируется список
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columns = *DataTypeNested::expandNestedColumns(columns);
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}
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else if (type == DROP_COLUMN)
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{
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/// look for a column in list and remove it if present, also removing corresponding entry from column_defaults
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const auto remove_column = [&column_defaults, this] (NamesAndTypesList & columns) {
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auto removed = false;
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NamesAndTypesList::iterator column_it;
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while (columns.end() != (column_it = std::find_if(columns.begin(), columns.end(),
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std::bind(namesEqual, std::cref(column_name), std::placeholders::_1))))
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{
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removed = true;
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column_it = columns.erase(column_it);
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column_defaults.erase(column_name);
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}
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return removed;
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};
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if (!remove_column(columns) &&
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!remove_column(materialized_columns) &&
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!remove_column(alias_columns))
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{
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throw Exception("Wrong column name. Cannot find column " + column_name + " to drop",
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DB::ErrorCodes::ILLEGAL_COLUMN);
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}
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}
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else if (type == MODIFY_COLUMN)
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{
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const auto default_it = column_defaults.find(column_name);
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const auto had_default_expr = default_it != std::end(column_defaults);
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const auto old_default_type = had_default_expr ? default_it->second.type : ColumnDefaultType{};
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/// target column list
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auto & new_columns = default_type == ColumnDefaultType::Default ?
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columns : default_type == ColumnDefaultType::Materialized ?
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materialized_columns : alias_columns;
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/// find column or throw exception
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const auto find_column = [this] (NamesAndTypesList & columns) {
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const auto it = std::find_if(columns.begin(), columns.end(),
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std::bind(namesEqual, std::cref(column_name), std::placeholders::_1) );
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if (it == columns.end())
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throw Exception("Wrong column name. Cannot find column " + column_name + " to modify",
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DB::ErrorCodes::ILLEGAL_COLUMN);
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return it;
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};
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/// if default types differ, remove column from the old list, then add to the new list
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if (default_type != old_default_type)
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{
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/// source column list
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auto & old_columns = old_default_type == ColumnDefaultType::Default ?
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columns : old_default_type == ColumnDefaultType::Materialized ?
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materialized_columns : alias_columns;
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const auto old_column_it = find_column(old_columns);
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new_columns.emplace_back(*old_column_it);
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old_columns.erase(old_column_it);
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/// do not forget to change the default type of old column
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if (had_default_expr)
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column_defaults[column_name].type = default_type;
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}
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/// find column in one of three column lists
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const auto column_it = find_column(new_columns);
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column_it->type = data_type;
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if (!default_expression && had_default_expr)
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/// new column has no default expression, remove it from column_defaults along with it's type
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column_defaults.erase(column_name);
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else if (default_expression && !had_default_expr)
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/// new column has a default expression while the old one had not, add it it column_defaults
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column_defaults.emplace(column_name, ColumnDefault{default_type, default_expression});
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else if (had_default_expr)
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/// both old and new columns have default expression, update it
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column_defaults[column_name].expression = default_expression;
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}
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else if (type == MODIFY_PRIMARY_KEY)
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{
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/// Это никак не относится к изменению списка столбцов.
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/// TODO Проверять, что все столбцы существуют, что добавляются только столбцы с константными default-ами.
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}
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else
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throw Exception("Wrong parameter type in ALTER query", ErrorCodes::LOGICAL_ERROR);
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}
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void AlterCommands::apply(NamesAndTypesList & columns,
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NamesAndTypesList & materialized_columns,
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NamesAndTypesList & alias_columns,
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ColumnDefaults & column_defaults) const
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{
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auto new_columns = columns;
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auto new_materialized_columns = materialized_columns;
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auto new_alias_columns = alias_columns;
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auto new_column_defaults = column_defaults;
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for (const AlterCommand & command : *this)
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command.apply(new_columns, new_materialized_columns, new_alias_columns, new_column_defaults);
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columns = std::move(new_columns);
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materialized_columns = std::move(new_materialized_columns);
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alias_columns = std::move(new_alias_columns);
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column_defaults = std::move(new_column_defaults);
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}
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void AlterCommands::validate(IStorage * table, const Context & context)
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{
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auto columns = table->getColumnsList();
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columns.insert(std::end(columns), std::begin(table->alias_columns), std::end(table->alias_columns));
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auto defaults = table->column_defaults;
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std::vector<std::pair<NameAndTypePair, AlterCommand *>> defaulted_columns{};
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ASTPtr default_expr_list{new ASTExpressionList};
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default_expr_list->children.reserve(defaults.size());
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for (AlterCommand & command : *this)
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{
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if (command.type == AlterCommand::ADD_COLUMN || command.type == AlterCommand::MODIFY_COLUMN)
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{
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const auto & column_name = command.column_name;
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const auto column_it = std::find_if(std::begin(columns), std::end(columns),
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std::bind(AlterCommand::namesEqual, std::cref(command.column_name), std::placeholders::_1));
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if (command.type == AlterCommand::ADD_COLUMN)
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{
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if (std::end(columns) != column_it)
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throw Exception{
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"Cannot add column " + column_name + ": column with this name already exisits",
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DB::ErrorCodes::ILLEGAL_COLUMN
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};
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}
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else if (command.type == AlterCommand::MODIFY_COLUMN)
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{
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if (std::end(columns) == column_it)
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throw Exception{
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"Wrong column name. Cannot find column " + column_name + " to modify",
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DB::ErrorCodes::ILLEGAL_COLUMN
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};
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columns.erase(column_it);
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defaults.erase(column_name);
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}
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/// we're creating dummy DataTypeUInt8 in order to prevent the NullPointerException in ExpressionActions
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columns.emplace_back(column_name, command.data_type ? command.data_type : new DataTypeUInt8);
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if (command.default_expression)
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{
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if (command.data_type)
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{
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const auto & final_column_name = column_name;
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const auto tmp_column_name = final_column_name + "_tmp";
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const auto column_type_raw_ptr = command.data_type.get();
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default_expr_list->children.emplace_back(setAlias(
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makeASTFunction("CAST", ASTPtr{new ASTIdentifier{{}, tmp_column_name}},
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ASTPtr{new ASTLiteral{{}, column_type_raw_ptr->getName()}}),
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final_column_name));
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default_expr_list->children.emplace_back(setAlias(command.default_expression->clone(), tmp_column_name));
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defaulted_columns.emplace_back(NameAndTypePair{column_name, command.data_type}, &command);
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}
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else
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{
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/// no type explicitly specified, will deduce later
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default_expr_list->children.emplace_back(
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setAlias(command.default_expression->clone(), column_name));
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defaulted_columns.emplace_back(NameAndTypePair{column_name, nullptr}, &command);
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}
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}
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}
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else if (command.type == AlterCommand::DROP_COLUMN)
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{
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auto found = false;
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for (auto it = std::begin(columns); it != std::end(columns);)
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if (AlterCommand::namesEqual(command.column_name, *it))
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{
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found = true;
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it = columns.erase(it);
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}
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else
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++it;
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for (auto it = std::begin(defaults); it != std::end(defaults);)
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if (AlterCommand::namesEqual(command.column_name, { it->first, nullptr }))
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it = defaults.erase(it);
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else
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++it;
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if (!found)
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throw Exception("Wrong column name. Cannot find column " + command.column_name + " to drop",
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DB::ErrorCodes::ILLEGAL_COLUMN);
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}
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}
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/** Existing defaulted columns may require default expression extensions with a type conversion,
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* therefore we add them to defaulted_columns to allow further processing */
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for (const auto & col_def : defaults)
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{
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const auto & column_name = col_def.first;
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const auto column_it = std::find_if(columns.begin(), columns.end(), [&] (const NameAndTypePair & name_type) {
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return AlterCommand::namesEqual(column_name, name_type);
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});
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const auto tmp_column_name = column_name + "_tmp";
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const auto & column_type_ptr = column_it->type;
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default_expr_list->children.emplace_back(setAlias(
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makeASTFunction("CAST", ASTPtr{new ASTIdentifier{{}, tmp_column_name}},
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ASTPtr{new ASTLiteral{{}, column_type_ptr->getName()}}),
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column_name));
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default_expr_list->children.emplace_back(setAlias(col_def.second.expression->clone(), tmp_column_name));
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defaulted_columns.emplace_back(NameAndTypePair{column_name, column_type_ptr}, nullptr);
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}
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const auto actions = ExpressionAnalyzer{default_expr_list, context, {}, columns}.getActions(true);
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const auto block = actions->getSampleBlock();
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/// set deduced types, modify default expression if necessary
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for (auto & defaulted_column : defaulted_columns)
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{
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const auto & name_and_type = defaulted_column.first;
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AlterCommand * & command_ptr = defaulted_column.second;
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const auto & column_name = name_and_type.name;
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const auto has_explicit_type = nullptr != name_and_type.type;
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/// default expression on old column
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if (has_explicit_type)
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{
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const auto & explicit_type = name_and_type.type;
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const auto & tmp_column = block.getByName(column_name + "_tmp");
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const auto & deduced_type = tmp_column.type;
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// column not specified explicitly in the ALTER query may require default_expression modification
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if (explicit_type->getName() != deduced_type->getName())
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{
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const auto default_it = defaults.find(column_name);
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/// column has no associated alter command, let's create it
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if (!command_ptr)
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{
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/// add a new alter command to modify existing column
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this->emplace_back(AlterCommand{
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AlterCommand::MODIFY_COLUMN, column_name, explicit_type,
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default_it->second.type, default_it->second.expression
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});
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command_ptr = &this->back();
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}
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command_ptr->default_expression = makeASTFunction("CAST", command_ptr->default_expression->clone(),
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ASTPtr{new ASTLiteral{{}, explicit_type->getName()}});
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}
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}
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else
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{
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/// just set deduced type
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command_ptr->data_type = block.getByName(column_name).type;
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}
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}
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}
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}
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