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477 lines
18 KiB
C++
477 lines
18 KiB
C++
#include <Functions/FunctionFactory.h>
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#include <Functions/FunctionIfBase.h>
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#include <Columns/ColumnNullable.h>
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#include <Columns/ColumnConst.h>
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#include <Columns/ColumnsNumber.h>
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#include <Columns/MaskOperations.h>
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#include <Interpreters/castColumn.h>
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#include <Common/assert_cast.h>
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#include <Common/typeid_cast.h>
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#include <Interpreters/Context.h>
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#include <DataTypes/DataTypeNullable.h>
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#include <DataTypes/getLeastSupertype.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_TYPE_OF_ARGUMENT;
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extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
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extern const int NOT_IMPLEMENTED;
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extern const int LOGICAL_ERROR;
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}
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namespace
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{
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/// Function multiIf, which generalizes the function if.
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///
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/// Syntax: multiIf(cond_1, then_1, ..., cond_N, then_N, else)
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/// where N >= 1.
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///
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/// For all 1 <= i <= N, "cond_i" has type UInt8.
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/// Types of all the branches "then_i" and "else" have a common type.
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///
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/// Additionally the arguments, conditions or branches, support nullable types
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/// and the NULL value, with a NULL condition treated as false.
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class FunctionMultiIf final : public FunctionIfBase
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{
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public:
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static constexpr auto name = "multiIf";
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static FunctionPtr create(ContextPtr context_) { return std::make_shared<FunctionMultiIf>(context_); }
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explicit FunctionMultiIf(ContextPtr context_) : context(context_) { }
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String getName() const override { return name; }
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bool isVariadic() const override { return true; }
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bool isShortCircuit(ShortCircuitSettings & settings, size_t number_of_arguments) const override
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{
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settings.enable_lazy_execution_for_first_argument = false;
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settings.enable_lazy_execution_for_common_descendants_of_arguments = (number_of_arguments != 3);
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settings.force_enable_lazy_execution = false;
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return true;
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}
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bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
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size_t getNumberOfArguments() const override { return 0; }
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bool useDefaultImplementationForNulls() const override { return false; }
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bool useDefaultImplementationForNothing() const override { return false; }
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bool canBeExecutedOnLowCardinalityDictionary() const override { return false; }
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ColumnNumbers getArgumentsThatDontImplyNullableReturnType(size_t number_of_arguments) const override
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{
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ColumnNumbers args;
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for (size_t i = 0; i + 1 < number_of_arguments; i += 2)
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args.push_back(i);
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return args;
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}
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DataTypePtr getReturnTypeImpl(const DataTypes & args) const override
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{
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/// Arguments are the following: cond1, then1, cond2, then2, ... condN, thenN, else.
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auto for_conditions = [&args](auto && f)
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{
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size_t conditions_end = args.size() - 1;
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for (size_t i = 0; i < conditions_end; i += 2)
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f(args[i]);
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};
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auto for_branches = [&args](auto && f)
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{
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size_t branches_end = args.size();
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for (size_t i = 1; i < branches_end; i += 2)
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f(args[i]);
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f(args.back());
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};
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if (!(args.size() >= 3 && args.size() % 2 == 1))
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throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH, "Invalid number of arguments for function {}", getName());
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for_conditions([&](const DataTypePtr & arg)
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{
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const IDataType * nested_type;
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if (arg->isNullable())
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{
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if (arg->onlyNull())
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return;
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const DataTypeNullable & nullable_type = static_cast<const DataTypeNullable &>(*arg);
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nested_type = nullable_type.getNestedType().get();
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}
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else
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{
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nested_type = arg.get();
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}
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if (!WhichDataType(nested_type).isUInt8())
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throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal type {} of argument (condition) of function {}. "
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"Must be UInt8.", arg->getName(), getName());
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});
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DataTypes types_of_branches;
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types_of_branches.reserve(args.size() / 2 + 1);
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for_branches([&](const DataTypePtr & arg)
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{
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types_of_branches.emplace_back(arg);
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});
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return getLeastSupertype(types_of_branches);
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}
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struct Instruction
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{
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IColumn::Ptr condition = nullptr;
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IColumn::Ptr source = nullptr;
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bool condition_always_true = false;
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bool condition_is_nullable = false;
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bool source_is_constant = false;
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bool condition_is_short = false;
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bool source_is_short = false;
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size_t condition_index = 0;
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size_t source_index = 0;
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};
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ColumnPtr executeImpl(const ColumnsWithTypeAndName & args, const DataTypePtr & result_type, size_t input_rows_count) const override
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{
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ColumnsWithTypeAndName arguments = args;
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executeShortCircuitArguments(arguments);
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/** We will gather values from columns in branches to result column,
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* depending on values of conditions.
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*/
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std::vector<Instruction> instructions;
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instructions.reserve(arguments.size() / 2 + 1);
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Columns converted_columns_holder;
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converted_columns_holder.reserve(instructions.capacity());
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const DataTypePtr & return_type = result_type;
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for (size_t i = 0; i < arguments.size(); i += 2)
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{
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Instruction instruction;
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size_t source_idx = i + 1;
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bool last_else_branch = source_idx == arguments.size();
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if (last_else_branch)
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{
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/// The last, "else" branch can be treated as a branch with always true condition "else if (true)".
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--source_idx;
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instruction.condition_always_true = true;
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}
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else
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{
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IColumn::Ptr cond_col = arguments[i].column->convertToFullColumnIfLowCardinality();
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/// We skip branches that are always false.
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/// If we encounter a branch that is always true, we can finish.
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if (cond_col->onlyNull())
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continue;
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if (const auto * column_const = checkAndGetColumn<ColumnConst>(*cond_col))
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{
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Field value = column_const->getField();
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if (value.isNull())
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continue;
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if (value.get<UInt64>() == 0)
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continue;
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instruction.condition_always_true = true;
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}
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else
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{
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instruction.condition = cond_col;
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instruction.condition_is_nullable = instruction.condition->isNullable();
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}
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instruction.condition_is_short = cond_col->size() < arguments[0].column->size();
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}
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const ColumnWithTypeAndName & source_col = arguments[source_idx];
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instruction.source_is_short = source_col.column->size() < arguments[0].column->size();
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if (source_col.type->equals(*return_type))
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{
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instruction.source = source_col.column;
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}
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else
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{
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/// Cast all columns to result type.
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converted_columns_holder.emplace_back(castColumn(source_col, return_type));
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instruction.source = converted_columns_holder.back();
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}
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if (instruction.source && isColumnConst(*instruction.source))
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instruction.source_is_constant = true;
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instructions.emplace_back(std::move(instruction));
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if (instructions.back().condition_always_true)
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break;
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}
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/// Special case if first instruction condition is always true and source is constant
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if (instructions.size() == 1 && instructions.front().source_is_constant
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&& instructions.front().condition_always_true)
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{
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MutableColumnPtr res = return_type->createColumn();
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auto & instruction = instructions.front();
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res->insertFrom(assert_cast<const ColumnConst &>(*instruction.source).getDataColumn(), 0);
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return ColumnConst::create(std::move(res), instruction.source->size());
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}
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bool contains_short = false;
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for (const auto & instruction : instructions)
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{
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if (instruction.condition_is_short || instruction.source_is_short)
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{
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contains_short = true;
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break;
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}
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}
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const auto & settings = context->getSettingsRef();
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const WhichDataType which(result_type);
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bool execute_multiif_columnar
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= settings.allow_execute_multiif_columnar && !contains_short && (which.isInt() || which.isUInt() || which.isFloat());
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size_t rows = input_rows_count;
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if (!execute_multiif_columnar)
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{
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MutableColumnPtr res = return_type->createColumn();
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executeInstructions(instructions, rows, res);
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return std::move(res);
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}
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#define EXECUTE_INSTRUCTIONS_COLUMNAR(TYPE, INDEX) \
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if (which.is##TYPE()) \
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{ \
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MutableColumnPtr res = ColumnVector<TYPE>::create(rows); \
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executeInstructionsColumnar<TYPE, INDEX>(instructions, rows, res); \
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return std::move(res); \
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}
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#define ENUMERATE_NUMERIC_TYPES(M, INDEX) \
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M(UInt8, INDEX) \
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M(UInt16, INDEX) \
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M(UInt32, INDEX) \
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M(UInt64, INDEX) \
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M(Int8, INDEX) \
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M(Int16, INDEX) \
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M(Int32, INDEX) \
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M(Int64, INDEX) \
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M(UInt128, INDEX) \
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M(UInt256, INDEX) \
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M(Int128, INDEX) \
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M(Int256, INDEX) \
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M(Float32, INDEX) \
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M(Float64, INDEX) \
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throw Exception( \
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ErrorCodes::NOT_IMPLEMENTED, "Columnar execution of function {} not implemented for type {}", getName(), result_type->getName());
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size_t num_instructions = instructions.size();
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if (num_instructions <= std::numeric_limits<Int16>::max())
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{
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ENUMERATE_NUMERIC_TYPES(EXECUTE_INSTRUCTIONS_COLUMNAR, Int16)
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}
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else if (num_instructions <= std::numeric_limits<Int32>::max())
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{
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ENUMERATE_NUMERIC_TYPES(EXECUTE_INSTRUCTIONS_COLUMNAR, Int32)
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}
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else if (num_instructions <= std::numeric_limits<Int64>::max())
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{
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ENUMERATE_NUMERIC_TYPES(EXECUTE_INSTRUCTIONS_COLUMNAR, Int64)
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}
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else
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throw Exception(
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ErrorCodes::LOGICAL_ERROR, "Instruction size({}) of function {} is out of range", getName(), result_type->getName());
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}
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private:
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static void executeInstructions(std::vector<Instruction> & instructions, size_t rows, const MutableColumnPtr & res)
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{
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for (size_t i = 0; i < rows; ++i)
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{
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for (auto & instruction : instructions)
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{
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bool insert = false;
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size_t condition_index = instruction.condition_is_short ? instruction.condition_index++ : i;
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if (instruction.condition_always_true)
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insert = true;
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else if (!instruction.condition_is_nullable)
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insert = assert_cast<const ColumnUInt8 &>(*instruction.condition).getData()[condition_index];
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else
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{
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const ColumnNullable & condition_nullable = assert_cast<const ColumnNullable &>(*instruction.condition);
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const ColumnUInt8 & condition_nested = assert_cast<const ColumnUInt8 &>(condition_nullable.getNestedColumn());
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const NullMap & condition_null_map = condition_nullable.getNullMapData();
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insert = !condition_null_map[condition_index] && condition_nested.getData()[condition_index];
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}
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if (insert)
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{
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size_t source_index = instruction.source_is_short ? instruction.source_index++ : i;
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if (!instruction.source_is_constant)
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res->insertFrom(*instruction.source, source_index);
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else
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res->insertFrom(assert_cast<const ColumnConst &>(*instruction.source).getDataColumn(), 0);
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break;
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}
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}
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}
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}
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/// We should read source from which instruction on each row?
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template <typename S>
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static void calculateInserts(std::vector<Instruction> & instructions, size_t rows, PaddedPODArray<S> & inserts)
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{
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for (S i = static_cast<S>(instructions.size() - 1); i >= 0; --i)
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{
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auto & instruction = instructions[i];
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if (instruction.condition_always_true)
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{
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for (size_t row_i = 0; row_i < rows; ++row_i)
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inserts[row_i] = i;
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}
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else if (!instruction.condition_is_nullable)
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{
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const auto & cond_data = assert_cast<const ColumnUInt8 &>(*instruction.condition).getData();
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for (size_t row_i = 0; row_i < rows; ++row_i)
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{
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/// Equivalent to below code. But it is able to utilize SIMD instructions.
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/// if (cond_data[row_i])
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/// inserts[row_i] = i;
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inserts[row_i] += (!!cond_data[row_i]) * (i - inserts[row_i]);
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}
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}
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else
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{
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const ColumnNullable & condition_nullable = assert_cast<const ColumnNullable &>(*instruction.condition);
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const ColumnUInt8 & condition_nested = assert_cast<const ColumnUInt8 &>(condition_nullable.getNestedColumn());
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const auto & condition_nested_data = condition_nested.getData();
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const NullMap & condition_null_map = condition_nullable.getNullMapData();
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for (size_t row_i = 0; row_i < rows; ++row_i)
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{
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/// Equivalent to below code. But it is able to utilize SIMD instructions.
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/// if (!condition_null_map[row_i] && condition_nested_data[row_i])
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/// inserts[row_i] = i;
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inserts[row_i] += (~condition_null_map[row_i] & (!!condition_nested_data[row_i])) * (i - inserts[row_i]);
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}
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}
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}
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}
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template <typename T, typename S>
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static void executeInstructionsColumnar(std::vector<Instruction> & instructions, size_t rows, const MutableColumnPtr & res)
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{
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PaddedPODArray<S> inserts(rows, static_cast<S>(instructions.size()));
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calculateInserts(instructions, rows, inserts);
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PaddedPODArray<T> & res_data = assert_cast<ColumnVector<T> &>(*res).getData();
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for (size_t row_i = 0; row_i < rows; ++row_i)
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{
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auto & instruction = instructions[inserts[row_i]];
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auto ref = instruction.source->getDataAt(row_i);
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res_data[row_i] = *reinterpret_cast<const T*>(ref.data);
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}
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}
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static void executeShortCircuitArguments(ColumnsWithTypeAndName & arguments)
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{
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int last_short_circuit_argument_index = checkShortCircuitArguments(arguments);
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if (last_short_circuit_argument_index < 0)
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return;
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executeColumnIfNeeded(arguments[0]);
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/// Let's denote x_i' = maskedExecute(x_i, mask).
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/// multiIf(x_0, y_0, x_1, y_1, x_2, y_2, ..., x_{n-1}, y_{n-1}, y_n)
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/// We will support mask_i = !x_0 & !x_1 & ... & !x_i
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/// and condition_i = !x_0 & ... & !x_{i - 1} & x_i
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/// Base:
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/// mask_0 and condition_0 is 1 everywhere, x_0' = x_0.
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/// Iteration:
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/// condition_i = extractMask(mask_{i - 1}, x_{i - 1}')
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/// y_i' = maskedExecute(y_i, condition)
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/// mask_i = extractMask(mask_{i - 1}, !x_{i - 1}')
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/// x_i' = maskedExecute(x_i, mask)
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/// Also we will treat NULL as 0 if x_i' is Nullable.
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IColumn::Filter mask(arguments[0].column->size(), 1);
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MaskInfo mask_info = {.has_ones = true, .has_zeros = false};
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IColumn::Filter condition_mask(arguments[0].column->size());
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MaskInfo condition_mask_info = {.has_ones = true, .has_zeros = false};
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int i = 1;
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while (i <= last_short_circuit_argument_index)
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{
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auto & cond_column = arguments[i - 1].column;
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/// If condition is const or null and value is false, we can skip execution of expression after this condition.
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if ((isColumnConst(*cond_column) || cond_column->onlyNull()) && !cond_column->empty() && !cond_column->getBool(0))
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{
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condition_mask_info.has_ones = false;
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condition_mask_info.has_zeros = true;
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}
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else
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{
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copyMask(mask, condition_mask);
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condition_mask_info = extractMask(condition_mask, cond_column);
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maskedExecute(arguments[i], condition_mask, condition_mask_info);
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}
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/// Check if the condition is always true and we don't need to execute the rest arguments.
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if (!condition_mask_info.has_zeros)
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break;
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++i;
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if (i > last_short_circuit_argument_index)
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break;
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/// Extract mask only if it make sense.
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if (condition_mask_info.has_ones)
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mask_info = extractInvertedMask(mask, cond_column);
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/// mask is a inverted disjunction of previous conditions and if it doesn't have once, we don't need to execute the rest arguments.
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if (!mask_info.has_ones)
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break;
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maskedExecute(arguments[i], mask, mask_info);
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++i;
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}
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/// We could skip some arguments execution, but we cannot leave them as ColumnFunction.
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/// So, create an empty column with the execution result type.
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for (; i <= last_short_circuit_argument_index; ++i)
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executeColumnIfNeeded(arguments[i], true);
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}
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ContextPtr context;
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};
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}
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REGISTER_FUNCTION(MultiIf)
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{
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factory.registerFunction<FunctionMultiIf>();
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/// These are obsolete function names.
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factory.registerFunction<FunctionMultiIf>("caseWithoutExpr");
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factory.registerFunction<FunctionMultiIf>("caseWithoutExpression");
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}
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}
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