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39 lines
1014 B
C++
39 lines
1014 B
C++
#pragma once
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#include <Columns/IColumn.h>
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namespace DB
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{
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/// Support methods for implementation of WHERE, PREWHERE and HAVING.
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/// Analyze if the column for filter is constant thus filter is always false or always true.
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struct ConstantFilterDescription
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{
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bool always_false = false;
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bool always_true = false;
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ConstantFilterDescription() {}
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explicit ConstantFilterDescription(const IColumn & column);
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};
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/// Obtain a filter from non constant Column, that may have type: UInt8, Nullable(UInt8).
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struct FilterDescription
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{
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const IColumn::Filter * data = nullptr; /// Pointer to filter when it is not always true or always false.
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ColumnPtr data_holder; /// If new column was generated, it will be owned by holder.
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explicit FilterDescription(const IColumn & column);
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};
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struct ColumnWithTypeAndName;
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/// Will throw an exception if column_elem is cannot be used as a filter column.
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void checkColumnCanBeUsedAsFilter(const ColumnWithTypeAndName & column_elem);
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}
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