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47 lines
1.2 KiB
C++
47 lines
1.2 KiB
C++
#pragma once
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#include <DataStreams/IBlockInputStream.h>
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#include <Columns/FilterDescription.h>
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namespace DB
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{
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class ExpressionActions;
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/** Implements WHERE, HAVING operations.
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* A stream of blocks and an expression, which adds to the block one ColumnUInt8 column containing the filtering conditions, are passed as input.
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* The expression is evaluated and a stream of blocks is returned, which contains only the filtered rows.
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*/
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class FilterBlockInputStream : public IBlockInputStream
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{
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private:
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using ExpressionActionsPtr = std::shared_ptr<ExpressionActions>;
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public:
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FilterBlockInputStream(const BlockInputStreamPtr & input, ExpressionActionsPtr expression_,
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String filter_column_name_, bool remove_filter_ = false);
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String getName() const override;
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Block getTotals() override;
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Block getHeader() const override;
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protected:
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Block readImpl() override;
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bool remove_filter;
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private:
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ExpressionActionsPtr expression;
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Block header;
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String filter_column_name;
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ssize_t filter_column;
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ConstantFilterDescription constant_filter_description;
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Block removeFilterIfNeed(Block && block) const;
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};
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}
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