ClickHouse/dbms/src/Columns/ColumnFunction.cpp

#include <Interpreters/ExpressionActions.h>
#include <Columns/ColumnFunction.h>
#include <Columns/ColumnsCommon.h>
#include <Common/PODArray.h>
#include <IO/WriteHelpers.h>
#include <Functions/IFunction.h>


namespace DB
{

namespace ErrorCodes
{
    extern const int LOGICAL_ERROR;
}

ColumnFunction::ColumnFunction(size_t size, FunctionBasePtr function_, const ColumnsWithTypeAndName & columns_to_capture)
        : size_(size), function(function_)
{
    appendArguments(columns_to_capture);
}

MutableColumnPtr ColumnFunction::cloneResized(size_t size) const
{
    ColumnsWithTypeAndName capture = captured_columns;
    for (auto & column : capture)
        column.column = column.column->cloneResized(size);

    return ColumnFunction::create(size, function, capture);
}

ColumnPtr ColumnFunction::replicate(const Offsets & offsets) const
{
    if (size_ != offsets.size())
        throw Exception("Size of offsets (" + toString(offsets.size()) + ") doesn't match size of column ("
                        + toString(size_) + ")", ErrorCodes::SIZES_OF_COLUMNS_DOESNT_MATCH);

    ColumnsWithTypeAndName capture = captured_columns;
    for (auto & column : capture)
        column.column = column.column->replicate(offsets);

    size_t replicated_size = 0 == size_ ? 0 : offsets.back();
    return ColumnFunction::create(replicated_size, function, capture);
}

ColumnPtr ColumnFunction::cut(size_t start, size_t length) const
{
    ColumnsWithTypeAndName capture = captured_columns;
    for (auto & column : capture)
        column.column = column.column->cut(start, length);

    return ColumnFunction::create(length, function, capture);
}

ColumnPtr ColumnFunction::filter(const Filter & filt, ssize_t result_size_hint) const
{
    if (size_ != filt.size())
        throw Exception("Size of filter (" + toString(filt.size()) + ") doesn't match size of column ("
                        + toString(size_) + ")", ErrorCodes::SIZES_OF_COLUMNS_DOESNT_MATCH);

    ColumnsWithTypeAndName capture = captured_columns;
    for (auto & column : capture)
        column.column = column.column->filter(filt, result_size_hint);

    size_t filtered_size = 0;
    if (capture.empty())
        filtered_size = countBytesInFilter(filt);
    else
        filtered_size = capture.front().column->size();

    return ColumnFunction::create(filtered_size, function, capture);
}

ColumnPtr ColumnFunction::permute(const Permutation & perm, size_t limit) const
{
    if (limit == 0)
        limit = size_;
    else
        limit = std::min(size_, limit);

    if (perm.size() < limit)
        throw Exception("Size of permutation (" + toString(perm.size()) + ") is less than required ("
                        + toString(limit) + ")", ErrorCodes::SIZES_OF_COLUMNS_DOESNT_MATCH);

    ColumnsWithTypeAndName capture = captured_columns;
    for (auto & column : capture)
        column.column = column.column->permute(perm, limit);

    return ColumnFunction::create(limit, function, capture);
}

ColumnPtr ColumnFunction::index(const IColumn & indexes, size_t limit) const
{
    ColumnsWithTypeAndName capture = captured_columns;
    for (auto & column : capture)
        column.column = column.column->index(indexes, limit);

    return ColumnFunction::create(limit, function, capture);
}

std::vector<MutableColumnPtr> ColumnFunction::scatter(IColumn::ColumnIndex num_columns,
                                                      const IColumn::Selector & selector) const
{
    if (size_ != selector.size())
        throw Exception("Size of selector (" + toString(selector.size()) + ") doesn't match size of column ("
                        + toString(size_) + ")", ErrorCodes::SIZES_OF_COLUMNS_DOESNT_MATCH);

    std::vector<size_t> counts;
    if (captured_columns.empty())
        counts = countColumnsSizeInSelector(num_columns, selector);

    std::vector<ColumnsWithTypeAndName> captures(num_columns, captured_columns);

    for (size_t capture = 0; capture < captured_columns.size(); ++capture)
    {
        auto parts = captured_columns[capture].column->scatter(num_columns, selector);
        for (IColumn::ColumnIndex part = 0; part < num_columns; ++part)
            captures[part][capture].column = std::move(parts[part]);
    }

    std::vector<MutableColumnPtr> columns;
    columns.reserve(num_columns);
    for (IColumn::ColumnIndex part = 0; part < num_columns; ++part)
    {
        auto & capture = captures[part];
        size_t size__ = capture.empty() ? counts[part] : capture.front().column->size();
        columns.emplace_back(ColumnFunction::create(size__, function, std::move(capture)));
    }

    return columns;
}

size_t ColumnFunction::byteSize() const
{
    size_t total_size = 0;
    for (auto & column : captured_columns)
        total_size += column.column->byteSize();

    return total_size;
}

size_t ColumnFunction::allocatedBytes() const
{
    size_t total_size = 0;
    for (auto & column : captured_columns)
        total_size += column.column->allocatedBytes();

    return total_size;
}

void ColumnFunction::appendArguments(const ColumnsWithTypeAndName & columns)
{
    auto args = function->getArgumentTypes().size();
    auto were_captured = captured_columns.size();
    auto wanna_capture = columns.size();

    if (were_captured + wanna_capture > args)
        throw Exception("Cannot capture " + toString(wanna_capture) + " columns because function " + function->getName()
                        + " has " + toString(args) + " arguments" +
                        (were_captured ? " and " + toString(were_captured) + " columns have already been captured" : "")
                        + ".", ErrorCodes::LOGICAL_ERROR);

    for (const auto & column : columns)
        appendArgument(column);
}

void ColumnFunction::appendArgument(const ColumnWithTypeAndName & column)
{
    const auto & argumnet_types = function->getArgumentTypes();

    auto index = captured_columns.size();
    if (!column.type->equals(*argumnet_types[index]))
        throw Exception("Cannot capture column " + std::to_string(argumnet_types.size()) +
                        " because it has incompatible type: got " + column.type->getName() +
                        ", but " + argumnet_types[index]->getName() + " is expected.", ErrorCodes::LOGICAL_ERROR);

    captured_columns.push_back(column);
}

ColumnWithTypeAndName ColumnFunction::reduce() const
{
    auto args = function->getArgumentTypes().size();
    auto captured = captured_columns.size();

    if (args != captured)
        throw Exception("Cannot call function " + function->getName() + " because is has " + toString(args) +
                        "arguments but " + toString(captured) + " columns were captured.", ErrorCodes::LOGICAL_ERROR);

    Block block(captured_columns);
    block.insert({nullptr, function->getReturnType(), ""});

    ColumnNumbers arguments(captured_columns.size());
    for (size_t i = 0; i < captured_columns.size(); ++i)
        arguments[i] = i;

    function->execute(block, arguments, captured_columns.size(), size_);

    return block.getByPosition(captured_columns.size());
}

}