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#include <QueryPipeline/narrowPipe.h>
#include <random>
#include <Common/thread_local_rng.h>
#include <Processors/ConcatProcessor.h>
#include <QueryPipeline/Pipe.h>
namespace DB
{
namespace
{
using Distribution = std::vector<size_t>;
Distribution getDistribution(size_t from, size_t to)
{
Distribution distribution(from);
for (size_t i = 0; i < from; ++i)
distribution[i] = i % to;
std::shuffle(distribution.begin(), distribution.end(), thread_local_rng);
return distribution;
}
}
void narrowPipe(Pipe & pipe, size_t width)
{
size_t size = pipe.numOutputPorts();
if (size <= width)
return;
std::vector<std::vector<OutputPort *>> partitions(width);
auto distribution = getDistribution(size, width);
pipe.transform([&](OutputPortRawPtrs ports)
{
for (size_t i = 0; i < size; ++i)
partitions[distribution[i]].emplace_back(ports[i]);
Processors concats;
concats.reserve(width);
for (size_t i = 0; i < width; ++i)
{
auto concat = std::make_shared<ConcatProcessor>(partitions[i].at(0)->getHeader(),
partitions[i].size());
size_t next_port = 0;
for (auto & port : concat->getInputs())
{
connect(*partitions[i][next_port], port);
++next_port;
}
concats.emplace_back(std::move(concat));
}
return concats;
});
}
}
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