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#include <Processors/QueryPlan/DistinctStep.h>
#include <Processors/Transforms/DistinctSortedChunkTransform.h>
#include <Processors/Transforms/DistinctSortedTransform.h>
#include <Processors/Transforms/DistinctTransform.h>
#include <QueryPipeline/QueryPipelineBuilder.h>
#include <IO/Operators.h>
#include <Common/JSONBuilder.h>
#include <Core/SortDescription.h>
namespace DB
{
static ITransformingStep::Traits getTraits(bool pre_distinct)
{
const bool preserves_number_of_streams = pre_distinct;
return ITransformingStep::Traits
{
{
.returns_single_stream = !pre_distinct,
.preserves_number_of_streams = preserves_number_of_streams,
.preserves_sorting = preserves_number_of_streams,
},
{
.preserves_number_of_rows = false,
}
};
}
static SortDescription getSortDescription(const SortDescription & input_sort_desc, const Names& columns)
{
SortDescription distinct_sort_desc;
for (const auto & sort_column_desc : input_sort_desc)
{
if (std::find(begin(columns), end(columns), sort_column_desc.column_name) == columns.end())
break;
distinct_sort_desc.emplace_back(sort_column_desc);
}
return distinct_sort_desc;
}
DistinctStep::DistinctStep(
const DataStream & input_stream_,
const SizeLimits & set_size_limits_,
UInt64 limit_hint_,
const Names & columns_,
bool pre_distinct_,
bool optimize_distinct_in_order_)
: ITransformingStep(
input_stream_,
input_stream_.header,
getTraits(pre_distinct_))
, set_size_limits(set_size_limits_)
, limit_hint(limit_hint_)
, columns(columns_)
, pre_distinct(pre_distinct_)
, optimize_distinct_in_order(optimize_distinct_in_order_)
{
}
void DistinctStep::transformPipeline(QueryPipelineBuilder & pipeline, const BuildQueryPipelineSettings &)
{
if (!pre_distinct)
pipeline.resize(1);
if (optimize_distinct_in_order)
{
const auto & input_stream = input_streams.back();
const SortDescription distinct_sort_desc = getSortDescription(input_stream.sort_description, columns);
if (!distinct_sort_desc.empty())
{
/// pre-distinct for sorted chunks
if (pre_distinct)
{
pipeline.addSimpleTransform(
[&](const Block & header, QueryPipelineBuilder::StreamType stream_type) -> ProcessorPtr
{
if (stream_type != QueryPipelineBuilder::StreamType::Main)
return nullptr;
return std::make_shared<DistinctSortedChunkTransform>(
header,
set_size_limits,
limit_hint,
distinct_sort_desc,
columns,
input_stream.sort_scope == DataStream::SortScope::Stream);
});
return;
}
/// final distinct for sorted stream (sorting inside and among chunks)
if (input_stream.sort_scope == DataStream::SortScope::Global)
{
assert(input_stream.has_single_port);
if (distinct_sort_desc.size() < columns.size())
{
if (DistinctSortedTransform::isApplicable(pipeline.getHeader(), distinct_sort_desc, columns))
{
pipeline.addSimpleTransform(
[&](const Block & header, QueryPipelineBuilder::StreamType stream_type) -> ProcessorPtr
{
if (stream_type != QueryPipelineBuilder::StreamType::Main)
return nullptr;
return std::make_shared<DistinctSortedTransform>(
header, distinct_sort_desc, set_size_limits, limit_hint, columns);
});
return;
}
}
else
{
pipeline.addSimpleTransform(
[&](const Block & header, QueryPipelineBuilder::StreamType stream_type) -> ProcessorPtr
{
if (stream_type != QueryPipelineBuilder::StreamType::Main)
return nullptr;
return std::make_shared<DistinctSortedChunkTransform>(
header, set_size_limits, limit_hint, distinct_sort_desc, columns, true);
});
return;
}
}
}
}
pipeline.addSimpleTransform(
[&](const Block & header, QueryPipelineBuilder::StreamType stream_type) -> ProcessorPtr
{
if (stream_type != QueryPipelineBuilder::StreamType::Main)
return nullptr;
return std::make_shared<DistinctTransform>(header, set_size_limits, limit_hint, columns);
});
}
void DistinctStep::describeActions(FormatSettings & settings) const
{
String prefix(settings.offset, ' ');
settings.out << prefix << "Columns: ";
if (columns.empty())
settings.out << "none";
else
{
bool first = true;
for (const auto & column : columns)
{
if (!first)
settings.out << ", ";
first = false;
settings.out << column;
}
}
settings.out << '\n';
}
void DistinctStep::describeActions(JSONBuilder::JSONMap & map) const
{
auto columns_array = std::make_unique<JSONBuilder::JSONArray>();
for (const auto & column : columns)
columns_array->add(column);
map.add("Columns", std::move(columns_array));
}
void DistinctStep::updateOutputStream()
{
output_stream = createOutputStream(
input_streams.front(),
input_streams.front().header,
getTraits(pre_distinct).data_stream_traits);
}
}
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