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47 lines
1.6 KiB
C++
47 lines
1.6 KiB
C++
#pragma once
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#include <Core/Block.h>
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#include <Core/SortDescription.h>
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namespace DB
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{
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/// Sort one block by `description`. If limit != 0, then the partial sort of the first `limit` rows is produced.
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void sortBlock(Block & block, const SortDescription & description, UInt64 limit = 0);
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/** Used only in StorageMergeTree to sort the data with INSERT.
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* Sorting is stable. This is important for keeping the order of rows in the CollapsingMergeTree engine
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* - because based on the order of rows it is determined whether to delete or leave groups of rows when collapsing.
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* Collations are not supported. Partial sorting is not supported.
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*/
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void stableSortBlock(Block & block, const SortDescription & description);
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/** Same as stableSortBlock, but do not sort the block, but only calculate the permutation of the values,
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* so that you can rearrange the column values yourself.
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*/
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void stableGetPermutation(const Block & block, const SortDescription & description, IColumn::Permutation & out_permutation);
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/** Quickly check whether the block is already sorted. If the block is not sorted - returns false as fast as possible.
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* Collations are not supported.
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*/
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bool isAlreadySorted(const Block & block, const SortDescription & description);
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/// Column with description for sort
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struct ColumnWithSortDescription
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{
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const IColumn * column;
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SortColumnDescription description;
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/// It means, that this column is ColumnConst
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bool column_const = false;
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};
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using ColumnsWithSortDescriptions = std::vector<ColumnWithSortDescription>;
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ColumnsWithSortDescriptions getColumnsWithSortDescription(const Block & block, const SortDescription & description);
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}
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