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52 lines
1.5 KiB
C++
52 lines
1.5 KiB
C++
#pragma once
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#include <Processors/IProcessor.h>
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#include <Processors/RowsBeforeLimitCounter.h>
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#include <Core/SortDescription.h>
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namespace DB
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{
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/// Implementation for OFFSET N (without limit)
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/// This processor support multiple inputs and outputs (the same number).
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/// Each pair of input and output port works independently.
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class OffsetTransform final : public IProcessor
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{
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private:
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UInt64 offset;
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UInt64 rows_read = 0; /// including the last read block
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RowsBeforeLimitCounterPtr rows_before_limit_at_least;
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/// State of port's pair.
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/// Chunks from different port pairs are not mixed for better cache locality.
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struct PortsData
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{
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Chunk current_chunk;
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InputPort * input_port = nullptr;
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OutputPort * output_port = nullptr;
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bool is_finished = false;
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};
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std::vector<PortsData> ports_data;
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size_t num_finished_port_pairs = 0;
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public:
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OffsetTransform(const Block & header_, UInt64 offset_, size_t num_streams = 1);
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String getName() const override { return "Offset"; }
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Status prepare(const PortNumbers & /*updated_input_ports*/, const PortNumbers & /*updated_output_ports*/) override;
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Status prepare() override; /// Compatibility for TreeExecutor.
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Status preparePair(PortsData & data);
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void splitChunk(PortsData & data) const;
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InputPort & getInputPort() { return inputs.front(); }
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OutputPort & getOutputPort() { return outputs.front(); }
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void setRowsBeforeLimitCounter(RowsBeforeLimitCounterPtr counter) { rows_before_limit_at_least.swap(counter); }
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};
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}
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