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ClickHouse/dbms/src/Interpreters/ExpressionActions.cpp

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#include <Common/config.h>
#include <Common/ProfileEvents.h>
#include <Interpreters/ExpressionActions.h>
#include <Interpreters/ExpressionJIT.h>
#include <Interpreters/Join.h>
#include <Columns/ColumnsNumber.h>
#include <Columns/ColumnArray.h>
#include <Common/typeid_cast.h>
#include <DataTypes/DataTypeArray.h>
#include <Functions/FunctionFactory.h>
#include <Functions/IFunction.h>
#include <set>
#include <optional>
namespace ProfileEvents
{
extern const Event FunctionExecute;
}
namespace DB
{
namespace ErrorCodes
{
extern const int DUPLICATE_COLUMN;
extern const int UNKNOWN_IDENTIFIER;
extern const int UNKNOWN_ACTION;
extern const int NOT_FOUND_COLUMN_IN_BLOCK;
extern const int SIZES_OF_ARRAYS_DOESNT_MATCH;
extern const int TOO_MANY_TEMPORARY_COLUMNS;
extern const int TOO_MANY_TEMPORARY_NON_CONST_COLUMNS;
}
Names ExpressionAction::getNeededColumns() const
{
Names res = argument_names;
res.insert(res.end(), array_joined_columns.begin(), array_joined_columns.end());
for (const auto & column : projection)
res.push_back(column.first);
if (!source_name.empty())
res.push_back(source_name);
return res;
}
ExpressionAction ExpressionAction::applyFunction(const FunctionBuilderPtr & function_,
const std::vector<std::string> & argument_names_,
std::string result_name_)
{
if (result_name_ == "")
{
result_name_ = function_->getName() + "(";
for (size_t i = 0 ; i < argument_names_.size(); ++i)
{
if (i)
result_name_ += ", ";
result_name_ += argument_names_[i];
}
result_name_ += ")";
}
ExpressionAction a;
a.type = APPLY_FUNCTION;
a.result_name = result_name_;
a.function_builder = function_;
a.argument_names = argument_names_;
return a;
}
ExpressionAction ExpressionAction::addColumn(const ColumnWithTypeAndName & added_column_)
{
ExpressionAction a;
a.type = ADD_COLUMN;
a.result_name = added_column_.name;
a.result_type = added_column_.type;
a.added_column = added_column_.column;
return a;
}
ExpressionAction ExpressionAction::removeColumn(const std::string & removed_name)
{
ExpressionAction a;
a.type = REMOVE_COLUMN;
a.source_name = removed_name;
return a;
}
ExpressionAction ExpressionAction::copyColumn(const std::string & from_name, const std::string & to_name)
{
ExpressionAction a;
a.type = COPY_COLUMN;
a.source_name = from_name;
a.result_name = to_name;
return a;
}
ExpressionAction ExpressionAction::project(const NamesWithAliases & projected_columns_)
{
ExpressionAction a;
a.type = PROJECT;
a.projection = projected_columns_;
return a;
}
ExpressionAction ExpressionAction::project(const Names & projected_columns_)
{
ExpressionAction a;
a.type = PROJECT;
a.projection.resize(projected_columns_.size());
for (size_t i = 0; i < projected_columns_.size(); ++i)
a.projection[i] = NameWithAlias(projected_columns_[i], "");
return a;
}
ExpressionAction ExpressionAction::arrayJoin(const NameSet & array_joined_columns, bool array_join_is_left, const Context & context)
{
if (array_joined_columns.empty())
throw Exception("No arrays to join", ErrorCodes::LOGICAL_ERROR);
ExpressionAction a;
a.type = ARRAY_JOIN;
a.array_joined_columns = array_joined_columns;
a.array_join_is_left = array_join_is_left;
if (array_join_is_left)
a.function_builder = FunctionFactory::instance().get("emptyArrayToSingle", context);
return a;
}
ExpressionAction ExpressionAction::ordinaryJoin(std::shared_ptr<const Join> join_, const NamesAndTypesList & columns_added_by_join_)
{
ExpressionAction a;
a.type = JOIN;
a.join = join_;
a.columns_added_by_join = columns_added_by_join_;
return a;
}
void ExpressionAction::prepare(Block & sample_block)
{
// std::cerr << "preparing: " << toString() << std::endl;
/** Constant expressions should be evaluated, and put the result in sample_block.
*/
switch (type)
{
case APPLY_FUNCTION:
{
if (sample_block.has(result_name))
throw Exception("Column '" + result_name + "' already exists", ErrorCodes::DUPLICATE_COLUMN);
bool all_const = true;
ColumnNumbers arguments(argument_names.size());
for (size_t i = 0; i < argument_names.size(); ++i)
{
arguments[i] = sample_block.getPositionByName(argument_names[i]);
ColumnPtr col = sample_block.safeGetByPosition(arguments[i]).column;
if (!col || !col->isColumnConst())
all_const = false;
}
ColumnPtr new_column;
/// If all arguments are constants, and function is suitable to be executed in 'prepare' stage - execute function.
if (all_const && function->isSuitableForConstantFolding())
{
size_t result_position = sample_block.columns();
ColumnWithTypeAndName new_column;
new_column.name = result_name;
new_column.type = result_type;
sample_block.insert(std::move(new_column));
function->execute(sample_block, arguments, result_position);
/// If the result is not a constant, just in case, we will consider the result as unknown.
ColumnWithTypeAndName & col = sample_block.safeGetByPosition(result_position);
if (!col.column->isColumnConst())
{
col.column = nullptr;
}
else
{
/// All constant (literal) columns in block are added with size 1.
/// But if there was no columns in block before executing a function, the result has size 0.
/// Change the size to 1.
if (col.column->empty())
col.column = col.column->cloneResized(1);
}
}
else
{
sample_block.insert({nullptr, result_type, result_name});
}
break;
}
case ARRAY_JOIN:
{
for (const auto & name : array_joined_columns)
{
ColumnWithTypeAndName & current = sample_block.getByName(name);
const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(&*current.type);
if (!array_type)
throw Exception("ARRAY JOIN requires array argument", ErrorCodes::TYPE_MISMATCH);
current.type = array_type->getNestedType();
current.column = nullptr;
}
break;
}
case JOIN:
{
/// TODO join_use_nulls setting
for (const auto & col : columns_added_by_join)
sample_block.insert(ColumnWithTypeAndName(nullptr, col.type, col.name));
break;
}
case PROJECT:
{
Block new_block;
for (size_t i = 0; i < projection.size(); ++i)
{
const std::string & name = projection[i].first;
const std::string & alias = projection[i].second;
ColumnWithTypeAndName column = sample_block.getByName(name);
if (alias != "")
column.name = alias;
new_block.insert(std::move(column));
}
sample_block.swap(new_block);
break;
}
case REMOVE_COLUMN:
{
sample_block.erase(source_name);
break;
}
case ADD_COLUMN:
{
if (sample_block.has(result_name))
throw Exception("Column '" + result_name + "' already exists", ErrorCodes::DUPLICATE_COLUMN);
sample_block.insert(ColumnWithTypeAndName(added_column, result_type, result_name));
break;
}
case COPY_COLUMN:
{
result_type = sample_block.getByName(source_name).type;
sample_block.insert(ColumnWithTypeAndName(sample_block.getByName(source_name).column, result_type, result_name));
break;
}
default:
throw Exception("Unknown action type", ErrorCodes::UNKNOWN_ACTION);
}
}
void ExpressionAction::execute(Block & block) const
{
// std::cerr << "executing: " << toString() << std::endl;
if (type == REMOVE_COLUMN || type == COPY_COLUMN)
if (!block.has(source_name))
throw Exception("Not found column '" + source_name + "'. There are columns: " + block.dumpNames(), ErrorCodes::NOT_FOUND_COLUMN_IN_BLOCK);
if (type == ADD_COLUMN || type == COPY_COLUMN || type == APPLY_FUNCTION)
if (block.has(result_name))
throw Exception("Column '" + result_name + "' already exists", ErrorCodes::DUPLICATE_COLUMN);
switch (type)
{
case APPLY_FUNCTION:
{
ColumnNumbers arguments(argument_names.size());
for (size_t i = 0; i < argument_names.size(); ++i)
{
if (!block.has(argument_names[i]))
throw Exception("Not found column: '" + argument_names[i] + "'", ErrorCodes::NOT_FOUND_COLUMN_IN_BLOCK);
arguments[i] = block.getPositionByName(argument_names[i]);
}
size_t num_columns_without_result = block.columns();
block.insert({ nullptr, result_type, result_name});
ProfileEvents::increment(ProfileEvents::FunctionExecute);
function->execute(block, arguments, num_columns_without_result);
break;
}
case ARRAY_JOIN:
{
if (array_joined_columns.empty())
throw Exception("No arrays to join", ErrorCodes::LOGICAL_ERROR);
ColumnPtr any_array_ptr = block.getByName(*array_joined_columns.begin()).column;
if (ColumnPtr converted = any_array_ptr->convertToFullColumnIfConst())
any_array_ptr = converted;
const ColumnArray * any_array = typeid_cast<const ColumnArray *>(&*any_array_ptr);
if (!any_array)
throw Exception("ARRAY JOIN of not array: " + *array_joined_columns.begin(), ErrorCodes::TYPE_MISMATCH);
/// If LEFT ARRAY JOIN, then we create columns in which empty arrays are replaced by arrays with one element - the default value.
std::map<String, ColumnPtr> non_empty_array_columns;
if (array_join_is_left)
{
for (const auto & name : array_joined_columns)
{
auto src_col = block.getByName(name);
Block tmp_block{src_col, {{}, src_col.type, {}}};
function_builder->build({src_col})->execute(tmp_block, {0}, 1);
non_empty_array_columns[name] = tmp_block.safeGetByPosition(1).column;
}
any_array_ptr = non_empty_array_columns.begin()->second;
if (ColumnPtr converted = any_array_ptr->convertToFullColumnIfConst())
any_array_ptr = converted;
any_array = &typeid_cast<const ColumnArray &>(*any_array_ptr);
}
size_t columns = block.columns();
for (size_t i = 0; i < columns; ++i)
{
ColumnWithTypeAndName & current = block.safeGetByPosition(i);
if (array_joined_columns.count(current.name))
{
if (!typeid_cast<const DataTypeArray *>(&*current.type))
throw Exception("ARRAY JOIN of not array: " + current.name, ErrorCodes::TYPE_MISMATCH);
ColumnPtr array_ptr = array_join_is_left ? non_empty_array_columns[current.name] : current.column;
if (ColumnPtr converted = array_ptr->convertToFullColumnIfConst())
array_ptr = converted;
const ColumnArray & array = typeid_cast<const ColumnArray &>(*array_ptr);
if (!array.hasEqualOffsets(typeid_cast<const ColumnArray &>(*any_array_ptr)))
throw Exception("Sizes of ARRAY-JOIN-ed arrays do not match", ErrorCodes::SIZES_OF_ARRAYS_DOESNT_MATCH);
current.column = typeid_cast<const ColumnArray &>(*array_ptr).getDataPtr();
current.type = typeid_cast<const DataTypeArray &>(*current.type).getNestedType();
}
else
{
current.column = current.column->replicate(any_array->getOffsets());
}
}
break;
}
case JOIN:
{
join->joinBlock(block);
break;
}
case PROJECT:
{
Block new_block;
for (size_t i = 0; i < projection.size(); ++i)
{
const std::string & name = projection[i].first;
const std::string & alias = projection[i].second;
ColumnWithTypeAndName column = block.getByName(name);
if (alias != "")
column.name = alias;
new_block.insert(std::move(column));
}
block.swap(new_block);
break;
}
case REMOVE_COLUMN:
block.erase(source_name);
break;
case ADD_COLUMN:
block.insert({ added_column->cloneResized(block.rows()), result_type, result_name });
break;
case COPY_COLUMN:
block.insert({ block.getByName(source_name).column, result_type, result_name });
break;
default:
throw Exception("Unknown action type", ErrorCodes::UNKNOWN_ACTION);
}
}
void ExpressionAction::executeOnTotals(Block & block) const
{
if (type != JOIN)
execute(block);
else
join->joinTotals(block);
}
std::string ExpressionAction::toString() const
{
std::stringstream ss;
switch (type)
{
case ADD_COLUMN:
ss << "ADD " << result_name << " "
<< (result_type ? result_type->getName() : "(no type)") << " "
<< (added_column ? added_column->getName() : "(no column)");
break;
case REMOVE_COLUMN:
ss << "REMOVE " << source_name;
break;
case COPY_COLUMN:
ss << "COPY " << result_name << " = " << source_name;
break;
case APPLY_FUNCTION:
ss << "FUNCTION " << result_name << " "
<< (result_type ? result_type->getName() : "(no type)") << " = "
<< (function ? function->getName() : "(no function)") << "(";
for (size_t i = 0; i < argument_names.size(); ++i)
{
if (i)
ss << ", ";
ss << argument_names[i];
}
ss << ")";
break;
case ARRAY_JOIN:
ss << (array_join_is_left ? "LEFT " : "") << "ARRAY JOIN ";
for (NameSet::const_iterator it = array_joined_columns.begin(); it != array_joined_columns.end(); ++it)
{
if (it != array_joined_columns.begin())
ss << ", ";
ss << *it;
}
break;
case JOIN:
ss << "JOIN ";
for (NamesAndTypesList::const_iterator it = columns_added_by_join.begin(); it != columns_added_by_join.end(); ++it)
{
if (it != columns_added_by_join.begin())
ss << ", ";
ss << it->name;
}
break;
case PROJECT:
ss << "PROJECT ";
for (size_t i = 0; i < projection.size(); ++i)
{
if (i)
ss << ", ";
ss << projection[i].first;
if (projection[i].second != "" && projection[i].second != projection[i].first)
ss << " AS " << projection[i].second;
}
break;
default:
throw Exception("Unexpected Action type", ErrorCodes::LOGICAL_ERROR);
}
return ss.str();
}
void ExpressionActions::checkLimits(Block & block) const
{
if (settings.max_temporary_columns && block.columns() > settings.max_temporary_columns)
throw Exception("Too many temporary columns: " + block.dumpNames()
+ ". Maximum: " + settings.max_temporary_columns.toString(),
ErrorCodes::TOO_MANY_TEMPORARY_COLUMNS);
if (settings.max_temporary_non_const_columns)
{
size_t non_const_columns = 0;
for (size_t i = 0, size = block.columns(); i < size; ++i)
if (block.safeGetByPosition(i).column && !block.safeGetByPosition(i).column->isColumnConst())
++non_const_columns;
if (non_const_columns > settings.max_temporary_non_const_columns)
{
std::stringstream list_of_non_const_columns;
for (size_t i = 0, size = block.columns(); i < size; ++i)
if (!block.safeGetByPosition(i).column->isColumnConst())
list_of_non_const_columns << "\n" << block.safeGetByPosition(i).name;
throw Exception("Too many temporary non-const columns:" + list_of_non_const_columns.str()
+ ". Maximum: " + settings.max_temporary_non_const_columns.toString(),
ErrorCodes::TOO_MANY_TEMPORARY_NON_CONST_COLUMNS);
}
}
}
void ExpressionActions::addInput(const ColumnWithTypeAndName & column)
{
input_columns.emplace_back(column.name, column.type);
sample_block.insert(column);
}
void ExpressionActions::addInput(const NameAndTypePair & column)
{
addInput(ColumnWithTypeAndName(nullptr, column.type, column.name));
}
void ExpressionActions::add(const ExpressionAction & action, Names & out_new_columns)
{
addImpl(action, out_new_columns);
}
void ExpressionActions::add(const ExpressionAction & action)
{
Names new_names;
addImpl(action, new_names);
}
void ExpressionActions::addImpl(ExpressionAction action, Names & new_names)
{
if (sample_block.has(action.result_name))
return;
if (action.result_name != "")
new_names.push_back(action.result_name);
new_names.insert(new_names.end(), action.array_joined_columns.begin(), action.array_joined_columns.end());
if (action.type == ExpressionAction::APPLY_FUNCTION)
{
if (sample_block.has(action.result_name))
throw Exception("Column '" + action.result_name + "' already exists", ErrorCodes::DUPLICATE_COLUMN);
ColumnsWithTypeAndName arguments(action.argument_names.size());
for (size_t i = 0; i < action.argument_names.size(); ++i)
{
if (!sample_block.has(action.argument_names[i]))
throw Exception("Unknown identifier: '" + action.argument_names[i] + "'", ErrorCodes::UNKNOWN_IDENTIFIER);
arguments[i] = sample_block.getByName(action.argument_names[i]);
}
action.function = action.function_builder->build(arguments);
action.result_type = action.function->getReturnType();
}
action.prepare(sample_block);
actions.push_back(action);
}
void ExpressionActions::prependProjectInput()
{
actions.insert(actions.begin(), ExpressionAction::project(getRequiredColumns()));
}
void ExpressionActions::prependArrayJoin(const ExpressionAction & action, const Block & sample_block)
{
if (action.type != ExpressionAction::ARRAY_JOIN)
throw Exception("ARRAY_JOIN action expected", ErrorCodes::LOGICAL_ERROR);
NameSet array_join_set(action.array_joined_columns.begin(), action.array_joined_columns.end());
for (auto & it : input_columns)
{
if (array_join_set.count(it.name))
{
array_join_set.erase(it.name);
it.type = std::make_shared<DataTypeArray>(it.type);
}
}
for (const std::string & name : array_join_set)
{
input_columns.emplace_back(name, sample_block.getByName(name).type);
actions.insert(actions.begin(), ExpressionAction::removeColumn(name));
}
actions.insert(actions.begin(), action);
optimizeArrayJoin();
}
bool ExpressionActions::popUnusedArrayJoin(const Names & required_columns, ExpressionAction & out_action)
{
if (actions.empty() || actions.back().type != ExpressionAction::ARRAY_JOIN)
return false;
NameSet required_set(required_columns.begin(), required_columns.end());
for (const std::string & name : actions.back().array_joined_columns)
{
if (required_set.count(name))
return false;
}
for (const std::string & name : actions.back().array_joined_columns)
{
DataTypePtr & type = sample_block.getByName(name).type;
type = std::make_shared<DataTypeArray>(type);
}
out_action = actions.back();
actions.pop_back();
return true;
}
void ExpressionActions::execute(Block & block) const
{
for (const auto & action : actions)
{
action.execute(block);
checkLimits(block);
}
}
void ExpressionActions::executeOnTotals(Block & block) const
{
/// If there is `totals` in the subquery for JOIN, but we do not have totals, then take the block with the default values instead of `totals`.
if (!block)
{
bool has_totals_in_join = false;
for (const auto & action : actions)
{
if (action.join && action.join->hasTotals())
{
has_totals_in_join = true;
break;
}
}
if (has_totals_in_join)
{
for (const auto & name_and_type : input_columns)
{
auto column = name_and_type.type->createColumn();
column->insertDefault();
block.insert(ColumnWithTypeAndName(std::move(column), name_and_type.type, name_and_type.name));
}
}
else
return; /// There's nothing to JOIN.
}
for (const auto & action : actions)
action.executeOnTotals(block);
}
std::string ExpressionActions::getSmallestColumn(const NamesAndTypesList & columns)
{
std::optional<size_t> min_size;
String res;
for (const auto & column : columns)
{
/// @todo resolve evil constant
size_t size = column.type->haveMaximumSizeOfValue() ? column.type->getMaximumSizeOfValueInMemory() : 100;
if (!min_size || size < *min_size)
{
min_size = size;
res = column.name;
}
}
if (!min_size)
throw Exception("No available columns", ErrorCodes::LOGICAL_ERROR);
return res;
}
void ExpressionActions::finalize(const Names & output_columns)
{
NameSet final_columns;
for (size_t i = 0; i < output_columns.size(); ++i)
{
const std::string & name = output_columns[i];
if (!sample_block.has(name))
throw Exception("Unknown column: " + name + ", there are only columns "
+ sample_block.dumpNames(), ErrorCodes::UNKNOWN_IDENTIFIER);
final_columns.insert(name);
}
#if USE_EMBEDDED_COMPILER
/// This has to be done before removing redundant actions and inserting REMOVE_COLUMNs
/// because inlining may change dependency sets.
compileFunctions(actions, output_columns, sample_block);
#endif
/// Which columns are needed to perform actions from the current to the last.
NameSet needed_columns = final_columns;
/// Which columns nobody will touch from the current action to the last.
NameSet unmodified_columns;
{
NamesAndTypesList sample_columns = sample_block.getNamesAndTypesList();
for (NamesAndTypesList::iterator it = sample_columns.begin(); it != sample_columns.end(); ++it)
unmodified_columns.insert(it->name);
}
/// Let's go from the end and maintain set of required columns at this stage.
/// We will throw out unnecessary actions, although usually they are absent by construction.
for (int i = static_cast<int>(actions.size()) - 1; i >= 0; --i)
{
ExpressionAction & action = actions[i];
Names in = action.getNeededColumns();
if (action.type == ExpressionAction::PROJECT)
{
needed_columns = NameSet(in.begin(), in.end());
unmodified_columns.clear();
}
else if (action.type == ExpressionAction::ARRAY_JOIN)
{
/// Do not ARRAY JOIN columns that are not used anymore.
/// Usually, such columns are not used until ARRAY JOIN, and therefore are ejected further in this function.
/// We will not remove all the columns so as not to lose the number of rows.
for (auto it = action.array_joined_columns.begin(); it != action.array_joined_columns.end();)
{
bool need = needed_columns.count(*it);
if (!need && action.array_joined_columns.size() > 1)
{
action.array_joined_columns.erase(it++);
}
else
{
needed_columns.insert(*it);
unmodified_columns.erase(*it);
/// If no ARRAY JOIN results are used, forcibly leave an arbitrary column at the output,
/// so you do not lose the number of rows.
if (!need)
final_columns.insert(*it);
++it;
}
}
}
else
{
std::string out = action.result_name;
if (!out.empty())
{
/// If the result is not used and there are no side effects, throw out the action.
if (!needed_columns.count(out) &&
(action.type == ExpressionAction::APPLY_FUNCTION
|| action.type == ExpressionAction::ADD_COLUMN
|| action.type == ExpressionAction::COPY_COLUMN))
{
actions.erase(actions.begin() + i);
if (unmodified_columns.count(out))
{
sample_block.erase(out);
unmodified_columns.erase(out);
}
continue;
}
unmodified_columns.erase(out);
needed_columns.erase(out);
/** If the function is a constant expression, then replace the action by adding a column-constant - result.
* That is, we perform constant folding.
*/
if (action.type == ExpressionAction::APPLY_FUNCTION && sample_block.has(out))
{
auto & result = sample_block.getByName(out);
if (result.column)
{
action.type = ExpressionAction::ADD_COLUMN;
action.result_type = result.type;
action.added_column = result.column;
action.function_builder = nullptr;
action.function = nullptr;
action.argument_names.clear();
in.clear();
}
}
}
needed_columns.insert(in.begin(), in.end());
}
}
/// We will not throw out all the input columns, so as not to lose the number of rows in the block.
if (needed_columns.empty() && !input_columns.empty())
needed_columns.insert(getSmallestColumn(input_columns));
/// We will not leave the block empty so as not to lose the number of rows in it.
if (final_columns.empty() && !input_columns.empty())
final_columns.insert(getSmallestColumn(input_columns));
for (NamesAndTypesList::iterator it = input_columns.begin(); it != input_columns.end();)
{
NamesAndTypesList::iterator it0 = it;
++it;
if (!needed_columns.count(it0->name))
{
if (unmodified_columns.count(it0->name))
sample_block.erase(it0->name);
input_columns.erase(it0);
}
}
/* std::cerr << "\n";
for (const auto & action : actions)
std::cerr << action.toString() << "\n";
std::cerr << "\n";*/
/// Deletes unnecessary temporary columns.
/// If the column after performing the function `refcount = 0`, it can be deleted.
std::map<String, int> columns_refcount;
for (const auto & name : final_columns)
++columns_refcount[name];
for (const auto & action : actions)
{
if (!action.source_name.empty())
++columns_refcount[action.source_name];
for (const auto & name : action.argument_names)
++columns_refcount[name];
for (const auto & name_alias : action.projection)
++columns_refcount[name_alias.first];
}
Actions new_actions;
new_actions.reserve(actions.size());
for (const auto & action : actions)
{
new_actions.push_back(action);
auto process = [&] (const String & name)
{
auto refcount = --columns_refcount[name];
if (refcount <= 0)
{
new_actions.push_back(ExpressionAction::removeColumn(name));
if (sample_block.has(name))
sample_block.erase(name);
}
};
if (!action.source_name.empty())
process(action.source_name);
for (const auto & name : action.argument_names)
process(name);
/// For `projection`, there is no reduction in `refcount`, because the `project` action replaces the names of the columns, in effect, already deleting them under the old names.
}
actions.swap(new_actions);
/* std::cerr << "\n";
for (const auto & action : actions)
std::cerr << action.toString() << "\n";
std::cerr << "\n";*/
optimizeArrayJoin();
checkLimits(sample_block);
}
std::string ExpressionActions::dumpActions() const
{
std::stringstream ss;
ss << "input:\n";
for (NamesAndTypesList::const_iterator it = input_columns.begin(); it != input_columns.end(); ++it)
ss << it->name << " " << it->type->getName() << "\n";
ss << "\nactions:\n";
for (size_t i = 0; i < actions.size(); ++i)
ss << actions[i].toString() << '\n';
ss << "\noutput:\n";
NamesAndTypesList output_columns = sample_block.getNamesAndTypesList();
for (NamesAndTypesList::const_iterator it = output_columns.begin(); it != output_columns.end(); ++it)
ss << it->name << " " << it->type->getName() << "\n";
return ss.str();
}
void ExpressionActions::optimizeArrayJoin()
{
const size_t NONE = actions.size();
size_t first_array_join = NONE;
/// Columns that need to be evaluated for arrayJoin.
/// Actions for adding them can not be moved to the left of the arrayJoin.
NameSet array_joined_columns;
/// Columns needed to evaluate arrayJoin or those that depend on it.
/// Actions to delete them can not be moved to the left of the arrayJoin.
NameSet array_join_dependencies;
for (size_t i = 0; i < actions.size(); ++i)
{
/// Do not move the action to the right of the projection (the more that they are not usually there).
if (actions[i].type == ExpressionAction::PROJECT)
break;
bool depends_on_array_join = false;
Names needed;
if (actions[i].type == ExpressionAction::ARRAY_JOIN)
{
depends_on_array_join = true;
needed = actions[i].getNeededColumns();
}
else
{
if (first_array_join == NONE)
continue;
needed = actions[i].getNeededColumns();
for (size_t j = 0; j < needed.size(); ++j)
{
if (array_joined_columns.count(needed[j]))
{
depends_on_array_join = true;
break;
}
}
}
if (depends_on_array_join)
{
if (first_array_join == NONE)
first_array_join = i;
if (actions[i].result_name != "")
array_joined_columns.insert(actions[i].result_name);
array_joined_columns.insert(actions[i].array_joined_columns.begin(), actions[i].array_joined_columns.end());
array_join_dependencies.insert(needed.begin(), needed.end());
}
else
{
bool can_move = false;
if (actions[i].type == ExpressionAction::REMOVE_COLUMN)
{
/// If you delete a column that is not needed for arrayJoin (and those who depend on it), you can delete it before arrayJoin.
can_move = !array_join_dependencies.count(actions[i].source_name);
}
else
{
/// If the action does not delete the columns and does not depend on the result of arrayJoin, you can make it until arrayJoin.
can_move = true;
}
/// Move the current action to the position just before the first arrayJoin.
if (can_move)
{
/// Move the i-th element to the position `first_array_join`.
std::rotate(actions.begin() + first_array_join, actions.begin() + i, actions.begin() + i + 1);
++first_array_join;
}
}
}
}
BlockInputStreamPtr ExpressionActions::createStreamWithNonJoinedDataIfFullOrRightJoin(const Block & source_header, size_t max_block_size) const
{
for (const auto & action : actions)
if (action.join && (action.join->getKind() == ASTTableJoin::Kind::Full || action.join->getKind() == ASTTableJoin::Kind::Right))
return action.join->createStreamWithNonJoinedRows(source_header, max_block_size);
return {};
}
void ExpressionActionsChain::addStep()
{
if (steps.empty())
throw Exception("Cannot add action to empty ExpressionActionsChain", ErrorCodes::LOGICAL_ERROR);
ColumnsWithTypeAndName columns = steps.back().actions->getSampleBlock().getColumnsWithTypeAndName();
steps.push_back(Step(std::make_shared<ExpressionActions>(columns, settings)));
}
void ExpressionActionsChain::finalize()
{
/// Finalize all steps. Right to left to define unnecessary input columns.
for (int i = static_cast<int>(steps.size()) - 1; i >= 0; --i)
{
Names required_output = steps[i].required_output;
if (i + 1 < static_cast<int>(steps.size()))
{
for (const auto & it : steps[i + 1].actions->getRequiredColumnsWithTypes())
required_output.push_back(it.name);
}
steps[i].actions->finalize(required_output);
}
/// When possible, move the ARRAY JOIN from earlier steps to later steps.
for (size_t i = 1; i < steps.size(); ++i)
{
ExpressionAction action;
if (steps[i - 1].actions->popUnusedArrayJoin(steps[i - 1].required_output, action))
steps[i].actions->prependArrayJoin(action, steps[i - 1].actions->getSampleBlock());
}
/// Adding the ejection of unnecessary columns to the beginning of each step.
for (size_t i = 1; i < steps.size(); ++i)
{
size_t columns_from_previous = steps[i - 1].actions->getSampleBlock().columns();
/// If unnecessary columns are formed at the output of the previous step, we'll add them to the beginning of this step.
/// Except when we drop all the columns and lose the number of rows in the block.
if (!steps[i].actions->getRequiredColumnsWithTypes().empty()
&& columns_from_previous > steps[i].actions->getRequiredColumnsWithTypes().size())
steps[i].actions->prependProjectInput();
}
}
std::string ExpressionActionsChain::dumpChain()
{
std::stringstream ss;
for (size_t i = 0; i < steps.size(); ++i)
{
ss << "step " << i << "\n";
ss << "required output:\n";
for (const std::string & name : steps[i].required_output)
ss << name << "\n";
ss << "\n" << steps[i].actions->dumpActions() << "\n";
}
return ss.str();
}
}
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