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39 lines
983 B
C++
39 lines
983 B
C++
#pragma once
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#include <DB/Storages/MergeTree/MergeSelector.h>
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namespace DB
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{
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class SimpleMergeSelector : public IMergeSelector
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{
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public:
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struct Settings
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{
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/** Minimum ratio of size of one part to all parts in set of parts to merge (for usual cases).
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* For example, if all parts have equal size, it means, that at least 'base' number of parts should be merged.
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* If parts has non-uniform sizes, then minumum number of parts to merge is effectively increased.
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* This behaviour balances merge-tree workload.
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* It called 'base', because merge-tree depth could be estimated as logarithm with that base.
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*/
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double base = 8;
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time_t lower_base_after = 300;
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/// Zero means unlimited.
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size_t max_parts_to_merge_at_once = 100;
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};
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SimpleMergeSelector(const Settings & settings) : settings(settings) {}
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PartsInPartition select(
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const Partitions & partitions,
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const size_t max_total_size_to_merge) override;
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private:
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const Settings settings;
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};
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}
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