ClickHouse/dbms/src/DataStreams/RollupBlockInputStream.cpp

73 lines
1.9 KiB
C++

#include <DataStreams/RollupBlockInputStream.h>
#include <DataStreams/finalizeBlock.h>
#include <DataTypes/DataTypeAggregateFunction.h>
#include <Columns/ColumnAggregateFunction.h>
#include <Columns/FilterDescription.h>
#include <Common/typeid_cast.h>
namespace DB
{
RollupBlockInputStream::RollupBlockInputStream(
const BlockInputStreamPtr & input_, const Aggregator::Params & params_) : aggregator(params_),
keys(params_.keys)
{
children.push_back(input_);
Aggregator::CancellationHook hook = [this]() { return this->isCancelled(); };
aggregator.setCancellationHook(hook);
}
Block RollupBlockInputStream::getHeader() const
{
Block res = children.at(0)->getHeader();
finalizeBlock(res);
return res;
}
Block RollupBlockInputStream::readImpl()
{
/** After reading a block from input stream,
* we will subsequently roll it up on next iterations of 'readImpl'
* by zeroing out every column one-by-one and re-merging a block.
*/
if (!is_data_read)
{
BlocksList source_blocks;
while (auto block = children[0]->read())
source_blocks.push_back(block);
if (source_blocks.empty())
return {};
is_data_read = true;
if (source_blocks.size() > 1)
rollup_block = aggregator.mergeBlocks(source_blocks, false);
else
rollup_block = std::move(source_blocks.front());
current_key = keys.size() - 1;
auto finalized = rollup_block;
finalizeBlock(finalized);
return finalized;
}
if (current_key < 0)
return {};
auto & current = rollup_block.getByPosition(keys[current_key]);
current.column = current.column->cloneEmpty()->cloneResized(rollup_block.rows());
--current_key;
BlocksList rollup_blocks = { rollup_block };
rollup_block = aggregator.mergeBlocks(rollup_blocks, false);
auto finalized = rollup_block;
finalizeBlock(finalized);
return finalized;
}
}