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Make custom upper_bound - probably will change it

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Anastasiya Rodigina 2019-05-27 10:50:37 +00:00
parent 76f2cbf677
commit 21e27cb854
1 changed files with 27 additions and 2 deletions
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29
dbms/src/DataStreams/FinishSortingBlockInputStream.cpp
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@ -50,7 +50,7 @@ struct Less
bool operator() (size_t a, size_t b) const
{
for (auto it = left_columns.begin(), jt = right_columns.begin(); it != left_columns.end() && jt != right_columns.end(); ++it, ++jt)
for (auto it = left_columns.begin(), jt = right_columns.begin(); it != left_columns.end(); ++it, ++jt)
{
int res = it->second.direction * it->first->compareAt(a, b, *jt->first, it->second.nulls_direction);
if (res < 0)
@ -62,6 +62,31 @@ struct Less
}
};
template<class ForwardIt, class T, class Comparator>
ForwardIt upperBoundWithoutSWO(ForwardIt first, ForwardIt last, const T& value, Comparator comp)
{
ForwardIt it;
typename std::iterator_traits<ForwardIt>::difference_type count, step;
count = std::distance(first, last);
while (count > 0)
{
it = first;
step = count / 2;
std::advance(it, step);
if (!comp(value, *it))
{
first = ++it;
count -= step + 1;
}
else
{
count = step;
}
}
return first;
}
Block FinishSortingBlockInputStream::readImpl()
{
if (limit && total_rows_processed >= limit)
@ -120,7 +145,7 @@ Block FinishSortingBlockInputStream::readImpl()
for (size_t i = 0; i < size; ++i)
perm[i] = i;
auto it = std::upper_bound(perm.begin(), perm.end(), last_block.rows() - 1, less);
auto it = upperBoundWithoutSWO(perm.begin(), perm.end(), last_block.rows() - 1, less);
/// We need to save tail of block, because next block may starts with the same key as in tail
/// and we should sort these rows in one chunk.